: The American V8 - Anatomy of a Hydrolock



Joey_Italiano
03-20-14, 07:37 PM
Introduction and Background

Hello All - first time user!

I have continuously visited this forum for peace of mind and advice ever since I purchased my 1997 Cadillac DeVille from a private seller on that fateful day 3 years ago. I read through thread after thread, my eyes growing wider and wider as I uncovered mystery after mystery. The pleasures and the pains of the delicate 275-hp aluminum flower that is the Northstar engine were revealed to me, often by experience. Here's the roller coaster of a relationship I've had with this land-yacht.

History


Purchased with 25,000 miles on the odometer and not a scratch on her and discovered early symptoms of blown head gasket in the first month. P0300 - random misfire caused by coolant leaking into the cylinders (buyer beware - feel my pain).
Paid $3000 to have the engine torn out, cracked in half and studded.
Still burnt oil so I decided to WOT and spun a bearing at 26,000 miles - oops!
Never had an issue with WOT before, so I had a serious talk with the mechanic who did the head gasket. That was a fun conversation where I said words like "lawyer", "small claims court" and "better business bureau".
Mechanic "felt bad" and took a little responsibility so he charged me $2,000 for a focused rebuild (block, rings, affected rods and bearings, etc. - a lot cheaper than legal fees!).
Mechanic installed wrong sized rings - another rebuild and engine block on the house! (then he felt really bad!)


Present Day

Finally. the car runs like a champ for 40,000 miles! Still burns a quart every 500 miles even with frequent WOT. I blame it on aggressive honing by his machine shop. Here we are, at 70,000 miles. I thought my relationship with the DeVille had grown comfortable. I pour oil into her crank case and she keeps tearing up the asphalt. One day, it starts pinging and smoking EVERYWHERE. Up hill, down hill, coasting, etc. Bad gas? dirty sensor? Lean mix?

So I clean the EGR, clean the throttle body (puked on with a quart of oil through the PCV every 500 miles), clean the MAF and change fuel filter... a whole lot less pinging but still on some hard 3000 rpm pulls.

Anatomy of a Hydrolock

This is where I got cocky and stupid - I figure, "why not try to steam-clean the engine by introducing water through the PCV line?". I've read that carbon accumulations can cause pre-ignition/detonation when they get hot. Water injection is a thing, even used by the US Airforce and some auto manufacturers! Seafoam seemed like a joke so I figured why not plain old water? I found a video of a man spraying a garden hose into his ford taurus' throttle body while revving the piss out of it. Of course, it was no northstar, but how could I screw this up? Here is exactly how I did it:


Engine fully warmed and at idle.
Use a tiny spray bottle to mist 400ml into the PCV hose - A little sputter and some white smoke - not much. Probably emptied the whole 400ml in about 3 minutes.
Spray another 400ml over two minutes or so - where are the clouds of steam and soot?
Quick rev to 2000 - oops.
Dislodges water (presumably pooled in the intake manifold, it doesn't stall but it random misfires (code confirmed by OBDII) for about 5 minutes while the engine shakes in its mounts and plumes of smoke come out the tailpipes).
Misfire ends and everything is back to normal
Scary, but I figure no damage, right, RIGHT? It didn't lock up! No bent rods, no cracked block, no cracked liners, etc?
I know, I should have kept the throttle open to 2000rpms to avoid pooling, but hindsight is 20/20.


Conclusion/Cry for Help

This is my problem, and I've lost sleep over it. How do I know if I did damage to that delicate flower that I have been showering with Benjamins? It is running well (arguably better and with less pinging than before). No mixture of oil and coolant (not even any water in oil from the "steam clean", no leaks (at least no NEW leaks).

But when does a hydrolock become a hydrolock? This is the thesis of my post.

If my math is correct, each piston displaces 575ml. With a 10.1 ratio, 57ml at TDC. If I introduced 800ml of water, I know the potential for hydrolock is definitely there. It didn't stall, but did I crush a bearing or put a hairline crack in a sleeve?

So - my main question. If the engine doesn't LOCK, is it a hydrolock? Can damage be done without a full engine seize? I'm hoping I just sucked enough water in slowly enough to make it miss a bit and no harm was done.

Parting Words

Yes - you can tell, I love this car. I am a slave to The American V8! These are the final years, fellow Kings of the Road. Electric cars are coming, gas is getting more expensive. I am proud to push this two-ton beast down the road with all my windows open, Creedence blasting, premium petroleum from the Cretaceous period exploding at 5500rpms, roaring by a Prius! You know why, cause this is AMERICA! And we drive CADILLACS! Be proud, Caddy drivers, and thanks for reading my story!

-Joey

Ranger
03-20-14, 08:58 PM
If the engine doesn't LOCK, is it a hydrolock?
No. That's the definition of a hydrolock. Filling the cylinder with liquid and then trying to compress it. Can't be done and something has to give, usually a rod through the side of the block. You got lucky. I don't think you damaged anything.

Used to use that water procedure many years ago on carbureted engines, but I would never try it anymore on one of these longitudinal manifolds.

Submariner409
03-21-14, 09:41 AM
Introducing ANY liquid in any form into the Northstar manifold has the potential for disaster. I have often wondered how the gods look over someone who pours snake oils into the engine through the PCV dirty air line. (The smoke looks neat, but accomplishes little or nothing)

See that bottom plenum-log ? Get "solid" liquid in there, suck some up an intake runner, and you get Ranger's picture - in spades.

This manifold is upside down - the black flat rectangle is the lower distribution plenum - that will hold over a quart of liquid.

Ranger
03-21-14, 10:00 AM
I have often wondered how the gods look over someone who pours snake oils into the engine through the PCV dirty air line.
Remember the old adage "God watches over fools and drunks"?

P.S.
No offense or insult intended Joey. :duck:

04GrandAmGT
03-24-14, 04:40 PM
Doesnt sound like you Damaged your engine. But thank goodness you didnt!! quart every 500 miles is about what my DTS does and it leaks most of it so i dont know how you are burning that much oil without seriously ruining those sparkplugs, but on an aside note, pre 2000 Northstars are 10.3:1 compression.

Joey_Italiano
07-08-14, 01:45 PM
Thanks for all the great info! Car is still running, but pinging again.

I had it motor-vac'd (see also: fuel injection service) about 4,000 miles ago and the ping is creeping back when the car is running hot (196-220'F).

By the way, if you ever get a fuel treatment done, make sure to drive the car hard afterwards. It was pinging worse after the treatment until I ejected soot all over the car behind me on the highway.

4,000 miles between engine cleaning is unacceptable. I will try some more WOT's, I usually don't put it in 2nd since I spun that bearing a while ago, but maybe it is necessary to suck all that carbon out with back pressure.

arctic_man
07-08-14, 03:53 PM
Thanks for all the great info! Car is still running, but pinging again.

I had it motor-vac'd (see also: fuel injection service) about 4,000 miles ago and the ping is creeping back when the car is running hot (196-220'F).

By the way, if you ever get a fuel treatment done, make sure to drive the car hard afterwards. It was pinging worse after the treatment until I ejected soot all over the car behind me on the highway.

4,000 miles between engine cleaning is unacceptable. I will try some more WOT's, I usually don't put it in 2nd since I spun that bearing a while ago, but maybe it is necessary to suck all that carbon out with back pressure.

196 to 220 is normal op temp. No AC and cruising mine sits at about 196. Stop and go, AC on, hot day, mine sits at 206 to 218. Have you pulled codes on this car before? If the knock is back and you WOT the car frequently, it probably isn't carbon slap. Is the knock coming from one cylinder or all/random?

Submariner409
07-08-14, 04:28 PM
4,000 miles between engine cleaning is unacceptable. I will try some more WOT's, I usually don't put it in 2nd since I spun that bearing a while ago, but maybe it is necessary to suck all that carbon out with back pressure.

There is no way on earth to "suck out carbon with back pressure". There is very, very little benefit in engine cleaning potions of any style. There is also no reason on earth to "clean" and engine every 4,000 miles.

Run a Top Tier gasoline, occasionally exercise the engine to its rpm limits in a couple of gears, keep it tuned and drive the car.

I'll bet the farm that you have EGR flow problems. (The engine is not "hot" at 195 - 215...... it's right on design operating temperature.)

Joey_Italiano
07-08-14, 09:48 PM
Thanks for your reply, submariner. I know engine braking is good for the rings at least. I use 91 or 93, usually from Sunoco. The motorvac treatment stopped the pinging dead in its tracks and the carbon that came out of the tailpipe was very impressive. I am positive the cleaning loosened up the really stuck on stuff that was potentially glowing and causing detonation when the engine gets thoroughly warmed (good to hear the temp is normal, but it never pings unless the engine is at operating temp for more than a half hour or so).

Trust me, I exercise this car frequently. No point in having a V8 if you don't stomp the pedal :)

Now, EGR flow. That's interesting. I cleaned the egr valve and passages about 1,000 miles ago. It was causing a code, but went away when I cleaned it. Any tips on egr maintenance?

I also know the vacuum tank has a small leak in it, but nothing major

Random thoughts: Fuel pressure regulator? Clogged cat?

Your help is appreciated!

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196 to 220 is normal op temp. No AC and cruising mine sits at about 196. Stop and go, AC on, hot day, mine sits at 206 to 218. Have you pulled codes on this car before? If the knock is back and you WOT the car frequently, it probably isn't carbon slap. Is the knock coming from one cylinder or all/random?

Thanks, arctic! Very similar operating temperatures. That's reassuring! I check codes frequently, I cleared up an egr code by cleaning the valve and now there are no codes except for some tape deck nonsense.

Knock seems to be one or two or more depending on how long I've been cruising. Seems to do it the most after a 1/2 hour of driving. Right in the 1700rpm - 2000rpm area. Only when the engine is very thoroughly warmed. Usually faint, but sometimes very loud

Is it possible that carbon is glowing after running it for a while causing detonation vs slap? (It does have a cold start knock/slap for the first minute in the morning).

The thing burns 1qt / 500 miles, I looked at the piston heads through the plug holes. Looks like BBQ crud.

Submariner409
07-09-14, 09:31 AM
The thing burns 1qt / 500 miles, I looked at the piston heads through the plug holes. Looks like BBQ crud.

That ^^^^^ information is a book in itself.

OK, I'll eat half my "carbon" blurb. 500 miles/quart is way more than excessive. You have problems like severely stuck/broken piston rings and/or worn valve stem seals.

Even that engine, with decent rings and tight valve stem seals, should get way over 2,000 miles/quart. Magic potions are not your answer. Serious engine mechanical repair is, and if the engine mileage is at or near 100,000 you're also looking at 32 hydraulic cam followers ("lifters") - the hardening eventually wears off the faces and you begin to eat cam lobes.

AhHah !!!! Your first post - "aggressive honing by the machine shop" - You DO NOT hone Northstar cylinders to install new rings (find Ranger's pictures of a Northstar block with 130,000 miles)........... and, almost a liter of liquid poured into the intake is almost a liter too much. You got problems. The sudden onset of oil usage and smoke was the telltale right there. I wonder if piston ring #2 is upside down on each piston ? They're tapered face scraper rings - install them upside down and they form a very efficient oil pump.

Joey_Italiano
07-09-14, 10:14 AM
AhHah !!!! Your first post - "aggressive honing by the machine shop" - You DO NOT hone Northstar cylinders to install new rings (find Ranger's pictures of a Northstar block with 130,000 miles)........... and, almost a liter of liquid poured into the intake is almost a liter too much. You got problems. The sudden onset of oil usage and smoke was the telltale right there. I wonder if piston ring #2 is upside down on each piston ? They're tapered face scraper rings - install them upside down and they form a very efficient oil pump.

I figured the guy didn't know what he was doing, but it was too late by the time he installed the wrong rings the first time. Had to let him try and make good for it. I can't believe he re-honed it when he shouldn't have, but it's right on my invoice. Any easy way to check if the rings are upside down? Lol. All cylinders are pretty cruddy so maybe the hone is the culprit. He said he replaced the valve stem seals. Maybe the improper rings screwed the ring landings?

Now the confusing thing to me is, it's been running fine for 35,000 miles before the carbon really got to it. If I give it a good clean, shouldn't it run fine until it builds up again? I know potions aren't the answer, but the improved performance after the fuel injection/top engine service was promising. I can't afford and don't really care about another rebuild. At this point, a jasper engine or maybe a brick on the pedal by the river is in order.

Maybe I'll just WOT it until the bottom end explodes.

Submariner409
07-09-14, 01:23 PM
Where are you ??? (Shop locations)

I hate to spend your money, but if the rest of the car is in decent or better condition ......... a bird in the hand........ Talk to Jake or Evrett at www.northstarperformance.com. Even if you are up to your ass in alligators right now, the car/engine can be saved.

Joey_Italiano
07-09-14, 03:32 PM
Ha! I'm located in Philadelphia, Pennsylvania. My mechanic (not the guy who flubbed the rebuild) won't touch the engine unless it's to replace it. It's a daily driver and driving is essential for my job. I miss my Buick. I'll talk to northstar performance, hopefully they can recommend some brave shops in my area.

Ranger
07-09-14, 08:31 PM
Maybe I'll just WOT it until the bottom end explodes.
Better have a lot of patience (and gasoline). When the Northstar was being tested they ran it at WOT for 12.5 days. Then shut it down and opened it up for inspection.

Submariner409
07-09-14, 08:45 PM
Joey, One of these quiet summer days you need to come down 13/301 to Kent Island. We'll tell lies, sea stories and swill a few beerz. I'll alert Charlie (The Transmission Man) just up the road and we'll put the beast up on a lift and take a look. (I'm not in the Northstar business - Olds 455s and GM 454s are my engine build work.)

Your first post - Electric cars - the ongoing progression to dumbing down Americans to the desired Lowest Common Denominator. I foresee the creation of yet another huge, crawling, amoebic government agency: The Office of Handicapper General - through which all Americans are drug and physically restricted to a certain level of capability so NO ONE is "better" than anyone else. Think about it. Worry. (Kurt Vonnegut ?)

Joey_Italiano
07-10-14, 09:46 PM
Submariner - that's only a 100 miles away or so. What are the chances we could drop a 455 or 454 in the deville? I contacted Jake at northstar performance. Sounds like he definitely knows his stuff! How does jasper compare? My local, trusted shop is Jasper certified and it would be a lot easier than shipping an engine from ontario.

The thing was pinging like crazy today. The warmer and more humid the air, the worse it seems. The rain we had yesterday and sudden drop in temperature stopped the pinging entirely. MAF? I did a proper WOT on it in 2nd on the highway today. No spun bearings! Put it in second and rocketed from 40 up to 70mph/5000rpms about 10 times. A little shy of 12.5 days but I don't think I've ever kept the RPMs that high for that long. No carbon came out of the exhaust. It must be gummed up pretty good or maybe it's not hotspots causing detonation afterall. It actually started pinging worse once I got into the city. Every stop sign take-off was a rattle-fest. Any chance it's a clogged cat holding back the exhaust gas? Bad fuel pressure? Still no codes, it only runs well at full throttle or idle.

I agree with you (and Vonnegut). Things are just easier when everyone falls into line and doesn't questions a thing, and governments know it. Although, I wouldn't mind a Tesla roadster.

Submariner409
07-11-14, 10:01 AM
Unfortunately there's no way on earth to go to a bigger GM engine in our FWD configuration.

Your whole rattle problem still sounds EGR-related. A clogged cat and the car would never get out of its own way. A clogged cat is like having 1/8" of gas pedal travel. EGR ping is classic - and your stoplight ping is the perfect description.

For a good Northstar I would try to work with Jake rather than a Jasper engine.

The WOT procedure does not depend on maintaining high RPM for any length of time - just the opposite. The idea is to accelerate from <10 mph with full gas pedal up to almost the 2-3 shift point - ~6300 rpm - then flip your foot off the gas pedal and let the engine pull the car back down to <10 mph.

This acceleration/deceleration procedure loads the pistons and rings with max power and heat, then totally unloads them - the idea being to cause the rings to break loose and rotate in their grooves, thus shedding carbon and dirt. Read the procedure way up ^^^ in the Cadillac Technical Archive - top black bar.

IF - IF the second piston rings on one or more pistons are installed upside down, if any rings are broken or cracked, or if a cylinder is improperly honed, nothing on earth short of complete overhaul will cure that amount of oil consumption.

Ranger
07-11-14, 10:12 AM
Yeah, a clogged or inoperative EGR will cause detonation as would a bad knock sensor, but an bad or stuck EGR valve or a bad knock sensor should set a DTC and trip the MIL, and a clogged EGR passage on the Northstar is unlikely, but in your case, probably worth inspecting anyway.

Joey_Italiano
07-11-14, 01:24 PM
Gentlemen,

Thanks for all your help and wisdom thus far. I was driving down the nj turnpike today, pinging at 60mph. I pulled over and pulled the harness on the EGR based on your hunch. Got back on the NJTP. NO PING! What the heck? Faulty EGR? Maybe I cleaned it one too many times and screwed it up? Runs a tiny bit rough without the egr, but ill take that over detonation!

Thoughts?

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What if it was running lean due to a vacuum leak or something and unplugging the egr just rebalanced the mixture? Stoichiometry!

Submariner409
07-11-14, 04:44 PM
EGR normally bleeds a metered amount of exhaust gas into the incoming fuel/air mixture at each intake port. This dilutes the air (oxygen) and slows combustion - therefore an absence of EGR should cause worse ping. EGR quantity constantly varies with engine load and airflow (power) demand.

Keep playing. You'll find the problem.

After a NJTP run (I hate that road after 57 years of up and down to Connecticut/RI), what is deposited in your tailpipe tips - dusty gray or fluffy black ? (Should be absolutely clean to maybe dusty brownish gray.)

Joey_Italiano
07-11-14, 05:03 PM
I know, very counterintuitive. I will leave it unplugged for now so my pistons don't melt. So odd, it ran great without the egr. Can't figure out what to play with next.

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Gotta love the turnpike! It's a good place to dump all those bodies that collect in the trunk of your Cadillac. Feds - if you are listening, I'm joking.

And the exhaust tips - they are always black, but I'll have to take a closer look at the most recent deposition. What does that indicate? Rich/lean mixture?

Submariner409
07-11-14, 05:09 PM
Black, wet is oil consumption
Black fluffy - soot - is rich fuel mixture
Dead white is extreme lean fuel mixture
Sorta brownish-gray is ideal

BUT reading tailpipes is like reading spark plugs - just a few minutes of slow, relatively cool combustion chamber temperatures changes everything.

Ranger
07-11-14, 08:58 PM
Have you verified that the knock sensor is functioning?

Joey_Italiano
07-11-14, 10:02 PM
Ranger,

No, I haven't. There are no codes. is there a layman's way to check the knock sensor without a deep scan tool? I know it's under the intake. Could be a fun afternoon to get to it!

I cleaned the EGR today just for good measure. It was crusty and a little sticky. We'll see what that does.

Ranger
07-12-14, 10:17 AM
I'm sure there is a way to test the knock sensor, but I don't know how. The FSM would be the source for that.

A "sticky" EGR could well have been your problem, BUT it is monitored and should have set a DTC if it where the problem.

Joey_Italiano
07-12-14, 08:00 PM
A lot smoother at idle after cleaning the EGR. Still pings like crazy on the highway. I've disconnected the egr for now to keep it from pinging.

I guess the next step is testing the knock sensor somehow or replacing the egr.

Ranger
07-12-14, 08:37 PM
:hmm: I don't get it. Theoretically it should ping more WITHOUT the EGR. :noidea:

Joey_Italiano
07-12-14, 09:22 PM
Very strange, but it works - looks like all I need is some electrical tape to cover up the check engine light.

Crazy thought, but maybe the blown by oil is leaning up the mix and the egr leaned it down to the point where it would ping. Now that the egr is out, it's not pinging. Maybe it's slowly converting itself to a diesel. Would be cool if I just threw some glow plugs in it.

----------

Anyway a bad o2 sensor could run it too lean?

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How about a vacuum leak? Any spots I should look for? Is the old carb cleaner and listen for an increased idle method the best way to check for a vacuum leak?

PaleAle
07-13-14, 09:55 AM
In post#9 you mentioned a known vacuum leak. Have you addressed that?

Ranger
07-13-14, 10:34 AM
The one vacuum leak point that most people don't see or think of is the manifold overpressure relief valve. Make sure that the orange seal is seated properly. If you have had a backfire recently, it may not be.

http://www.cadillacforums.com/forums/attachments/northstar-engines-system-technical-discussion/42633d1213058899-whistling-pressure-relief-n-intake-manifold-valve-closed.jpg

http://www.cadillacforums.com/forums/attachments/northstar-engines-system-technical-discussion/42634d1213058899-whistling-pressure-relief-n-intake-manifold-valve-open.jpg

RVMAN
07-14-14, 01:20 PM
Have you verified that the knock sensor is functioning?

change it.

Joey_Italiano
07-14-14, 06:41 PM
Ranger - over pressure relief valve? Who knew! Thanks for the lead!

The vacuum reservoir leak has not been addressed, but it hasn't been an issue unless it got worse.

So, today I reset the computer by unplugging the battery for 10 minutes. Ping is gone. I think it may have learned bad fuel trims with the clogged egr and once the egr was opened up, it was so lean it started knocking. Looks like the default fuel tables are working. I worry that it will drift back to lean once it "relearns", in which case I will keep chasing vacuum leaks.

Keep your fingers crossed!

Thanks everyone for your help and support with this old battle horse!

Joey_Italiano
07-17-14, 01:36 PM
Update:

The computer reset seems to have helped a lot. The ping is almost gone, still occasionally at cruising speed under load.

Ranger - I looked for vacuum leaks by spraying small amounts of throttle cleaner around the manifold and various hoses. I also sprayed by the pressure relief valve. No change in idle.

Ill tell you though, I tested what the idle change would sound like by pulling the pcv hose and spraying some cleaner by it. I went a little overboard and stalled it. When I went to start it, the thing backfired and saw the smoke blow out of the valve! Checked it again for tightness, seems good!

Thanks again!

Ranger
07-17-14, 08:36 PM
I went a little overboard and stalled it. When I went to start it, the thing backfired and saw the smoke blow out of the valve!

:) Bet that got your attention.

Joey_Italiano
07-26-14, 12:21 AM
Gentlemen,

More developments. After egr cleaning and resetting the computer, the car ran pretty well. Much less pinging but also not very "electric" smooth since the PCM was readjusting to all of its oil caked sensors.

I beat the balls off it hoping to clean out some carbon to stop pre ignition due to glowing piston gunk, but it only kept it from pinging real bad.

I resorted to sea foam in an aerosolized can. I figured that would prevent me from hydro locking it. I fed it in through the rear valve cover vent hose connected to the middle of the manifold just starboard of the throttle (nautical terms seem appropriate).

Gave it the old Italian tune up, coated the prius' windshield behind me with burnt up 10W-30 from the pre-Cambrian era, and voila!, running like new again.

I did make a discovery, the e-brake doesn't come up as fast as it used to. Vacuum leak?? Other than Viagra, how do I get that sucker to pop up again? It got stuck and I had to stomp on it and fiddle with the ac controls to get it to release. Do they make a replacement solenoid? I only found cables and springs online.

As always, you guys are the best.

PS - Man, I missed that clean engine throttle response. It's eerie not hearing the pinging when I drive by the highway divider. Who knew Cadillacs were supposed to run this quiet?

PPS - I'm starting to credit GM for running that thing WOT for a fortnight. I have been blasting that thing waiting for it to spin another bearing. Not sure why it spun the first time. It was only around 4000rpm for a few seconds. I have held it at 5700 when WOT'ing in 2nd gear before letting off and other than the tiniest shudder/miss, it won't break.

Ranger
07-26-14, 09:40 AM
I guess once in a while Seafoam does do some good.

The parking brake problem could be a very small leak in the release diaphragm or a cable beginning to get rusty.

Joey_Italiano
08-10-14, 06:16 PM
Guys,

I've been busy. I tried a new EGR valve, no luck so I returned it. I decided running with the EGR valve unplugged was the surest, easiest way to stop the pinging. However, this caused a check engine light.

I got cocky and made an egr blocking plate out of 1/16" aluminum and sandwiched it between the gasket and the egr valve. Once the old egr was bolted on top, it sealed the orifices very well. Plugged it back in and took it for a spin expecting no codes and no ping.

Wrong - no CEL, but the car still pings with the egr blocked and plugged in. Unplugged it again and now I have to pull the stupid plate out some day. So here's my big question:

What does the PCM do when you unplug the EGR? It must be changing the mix or something or maybe it's a different sensor causing the pinging.

O2 sensor + burnt oil = lean condition?

At least I know it's not the EGR! I think I need to get a bidirectional scan tool and start watching the fuel injectors and o2 sensors. Any recommendations for an inexpensive deep scanner?

Your help is always appreciated!

Thanks,

-Joe

Ranger
08-10-14, 09:23 PM
One thing recirculated exhaust gasses do is cool the combustion chamber.

Here is a lengthy, but good read regarding detonation. It may give you some insight or ideas.
http://www.contactmagazine.com/Issue54/EngineBasics.html

Joey_Italiano
08-10-14, 10:24 PM
Thanks, Ranger!

So we're still missing something important - here are the facts:

EGR unplugged (closed), block plate not installed - no ping
EGR unplugged (closed), block plate installed - no ping
EGR plugged in (normal operation), block plate not installed - ping
EGR plugged in, block plate installed (normal operation, but EGR is blocked) - PING, when the EGR is blocked off! This is my smoking gun to rule out EGR. Something else is happening with the computer when the EGR is unplugged.

So it's not the EGR valve causing the ping. Something changes when the EGR is unplugged regardless of exhaust gas flow.

Does the pcm have some kind of fail safe mode when the EGR is unplugged which would make the pinging go away by some other mechanism? Timing? mixture?

I have to find out what else changed when that EGR is unplugged.

Know any GM guys who designed this system? :)

Ranger
08-11-14, 10:58 AM
PING, when the EGR is blocked off! This is my smoking gun to rule out EGR. Something else is happening with the computer when the EGR is unplugged.


So it's not the EGR valve causing the ping. Something changes when the EGR is unplugged regardless of exhaust gas flow.
I agree


Does the pcm have some kind of fail safe mode when the EGR is unplugged which would make the pinging go away by some other mechanism? Timing? mixture?
I'm sure it does, but I think you'll need a FSM to find that out.



Know any GM guys who designed this system? :)
Yeah, but he no longer posts here.

Submariner409
08-11-14, 11:05 AM
The PCM has a "limp home" feature that, under certain engine controls/emissions fault conditions, defaults the ignition to a set advance of 10 degrees BTDC. Not sure if an EGR fault is one of those, but that sure would alleviate the ping, as well as give an overall feeling of general engine sluggishness and maybe a drop in fuel economy.

That diagnosis would come from the trees in the GM/Helm service manuals. eBay or www.helminc.com (http://www.helminc.com).

Joey_Italiano
08-11-14, 12:49 PM
Bingo!

It is a little sluggish and it gets about 2-3 less MPG on the highway. But at least it's not melting my pistons!

So if it is setting an advance of 10' BTDC, it stops the ping at the sake of performance. What is proper timing for a healthy engine?

What sensor(s) is/are responsible for setting timing? (I'm sure all of them). Whatever it is, it won't light up my check engine light or give a code.

I'm not sure what to check next. I know it was running real rich once a long while ago and that was the upstream O2 sensor, but that gave a code.

Is it possible for an O2 sensor to cause a lean condition?

the only other thing I can think of is major mechanical issues. Compression seems good, no major blow-by. Just burning oil and carboning up the chambers.

Maybe the pistons are carboned just enough to cause ping with more aggressive timing? That would explain why having it motor-vac'd and seafoaming gave temporary relief until the gunk built back up. Oil burn rates are the same as they were 40,000 miles ago so I can't figure out why this just started happening now. Unless the seafoam and motorvac were cleaning the O2 sensors just enough to stop ping.

Clogged EGR tubes?

I'm really close to my wit's end on this one. I've always been the kind of guy who believed you could do anything if you put your mind to it, but this engine is cursed.

Submariner409
08-11-14, 02:35 PM
The spray it and run it "carbon treatments" are doing little to no good. I often wonder how much the cat suffers from those treatments.

The GM vacuum job is more like a parts cleaning tank, though - it goes into all 8 cylinders, soaks for X hours, gets vacuumed out, the engine is run and the oil and filter changed immediately. That stuff is like dosing all 8 cylinders with pure lacquer thinner - incredibly solvent. It goes past the piston rings like ........ lacquer thinner.

"Burning carbon makes smoke !!!" Oh, really ??? How much smoke does gray/red charcoal give off ? The smoke you see is the snake oil burning, not carbon.

Your 1997 Deville engine management system uses a maximum timing advance of about 35 degrees BTDC - and the only time you'll ever see that is at highway road loads from 45 - 55 mph. At ALL other times the advance is incredibly dynamic and varies from 8 degrees to 30+ depending on speed, load, intake airflow, fuel flow, ambient temp, coolant temp, atmospheric pressure, fuel octane (what's actually in the tank, not what's on the pump) - other stuff. It's ALL entirely electronic - there are no mechanical inputs such as vacuum advance canisters, flyweights, or cap & rotor.

In a normally operating Northstar ignition system, because of the combustion chamber design and short piston stroke, timing drops back to 16 - 22 degrees BTDC during full power or passing runs. Most, if not all emissions systems are bypassed at WOT, and during a WOT run the A/C compressor turns off, too......... when that TPS hits 96% to 100% open, all sorts of different stuff goes on (or off).

Ranger
08-11-14, 03:19 PM
I can't help but wonder if you might not have a bad knock sensor.

Joey_Italiano
08-11-14, 03:59 PM
Ranger - That was RVMan's suggestion as well. I will check all the EGR lines and make sure they are free and clear. Than maybe I'll take the intake manifold off and check out the knock sensor.... oh boy.

Submariner - Pretty busy under that hood! Thanks for all the info. I tried the GM method and all the cleaner went right past the rings in less than 10 minutes. I changed the oil after running it for 10 minutes or so and then ran it hard to burn the rest off. What a mess. The fumes got me pretty stoned which was fun.

Ranger
08-11-14, 09:16 PM
Manifold removal is not as hard as it looks.

Joey_Italiano
08-12-14, 03:35 PM
Gents,

I fixed it. The front EGR tube was 90% blocked (see below). I scraped it out, hit it with some carb cleaner and soaked the tube. Put it back (stripped a couple threads on the mounting points, but it holds) and the ping vanished. Looks like it was the EGR after all! I'll remember this if it ever starts pinging again.

239450

I drove up and down the turnpike today for work, put about 200 miles on the clock. Check this fuel economy out:

239466

Like a 275HP, 2-ton Toyota!

Thanks for all your help, let's see what happens next. I bet a meteor will land on it tonight.

Submariner409
08-12-14, 03:56 PM
Good to see that you stuck with it and dug deep enough. Congrats.

(Now - your hunt might take you to cleaning other EGR passages - in the heads. Service manual time ?)

Joey_Italiano
08-13-14, 08:26 AM
Thanks Submariner - I thought the EGR system just dumped right into the spacer between the throttle and the intake manifold. Does it go through some other passages after that? Geez... I'm not taking the heads off that car!

So it looks like the unplugged EGR passages caused another code to pop up. P0174 - Fuel Trim System Lean Bank 2, unless this condition was covered up by some other issue. Does this mean it was running lean so the computer is dumping more fuel in? I don't want to spin another bearing.

Maybe cleaning all that gunk opened up a vacuum leak somewhere in the EGR loop? The code cycles between "history" and "current" randomly.

Or maybe it's that parking brake and vacuum reservoir coming back to haunt me! Eitherway, the car is running a lot better than before so it feels like progress. Just want to get that light to turn off for good!

P.S. - what service manual would you suggest? Haynes?

Ranger
08-13-14, 09:48 AM
DO NOT waste your money on Haynes or Chiltons. You want a FSM by Helm Inc.
Ebay is your friend

http://www.ebay.com/itm/97-1997-CADILLAC-DE-VILLE-ELDORADO-SEVILLE-REPAIR-SERVICE-MANUAL-SET-OF-2-/231286117879?pt=Motors_Manuals_Literature&hash=item35d9ba15f7&vxp=mtr

http://www.ebay.com/itm/1997-DEVILLE-ELDORADO-SEVILLE-2-VOLUME-SERVICE-SHOP-REPAIR-MANUAL-SET-/111303392947?pt=Motors_Manuals_Literature&hash=item19ea32feb3&vxp=mtr

http://www.ebay.com/itm/1997-Cadillac-DeVille-Eldorado-Seville-Service-Shop-Repair-Manual-Set-FACTORY-/351070837302?pt=Motors_Manuals_Literature&hash=item51bd73da36&vxp=mtr

http://www.ebay.com/itm/1997-Cadillac-Deville-Eldorado-Seville-service-manuals-Two-volumes-/281199362107?pt=Motors_Manuals_Literature&hash=item4178c9c03b&vxp=mtr

http://www.ebay.com/itm/1997-Cadillac-DeVille-Eldorado-Seville-TWO-Volume-Service-Manual-Set-/141369807046?pt=LH_DefaultDomain_0&hash=item20ea4c10c6

Joey_Italiano
08-13-14, 01:06 PM
Thanks Ranger! Never tried Helm before. Used a Haynes for my Buick and it was decent (did I mention how much I miss that car?), but this ain't no Buick!

So, any insight into why bank 2 and not bank 1 is lean? Maybe it's the O2 sensor itself gummed up with snake oil?

A couple other thoughts, is there any type of sealant I should have applied when I installed the EGR and gasket? Or maybe the sudden gain in air flow from the cleaned EGR pipes is confusing the system?

Otherwise, I'll be chasing vacuum leaks until the cows come home.

I saw your list in another thread:

http://www.cadillacforums.com/forums/northstar-engines-system-technical-discussion/41732-p0171-p0174.html

Ranger
08-13-14, 09:23 PM
Helm is the official service manual that would be in every dealer. Chilton & Haynes are for the weekend warriors that simply want to change oil, coolant and brakes. They're pretty useless for the serious wrench bender.


So, any insight into why bank 2 and not bank 1 is lean?
Vacuum leak, bank 2 would be my guess.

Joey_Italiano
08-13-14, 09:54 PM
I was spraying some carb cleaner around earlier and thought I heard some suction near the front of the manifold (bank 2). It was not accompanied by an increase in idle, so I can't say for sure. Maybe it is time I pulled that intake manifold off and checked the seals.

The code also seems to trip when I come to a stop at a light or put the car in park which also supports the vacuum leak idea.

My only other thought is loss of compression, I'm thinking of getting a testing gauge just to see how those rings are holding up.

Do you think this is something I should get ironed out right away or can I take my time on this? I don't want to dilute my oil by running rich.

98eldo32v
08-14-14, 04:56 AM
Well,


I have read this post.......


I hate to be the bearer of bad news.......

First and foremost....repair all vacuum leaks......

Vacuum leaks make the car lean and the computer wants to richen up the mixture to compensate.

Now, I might be telling my age here when I used to play with distributors weights, springs and adjustable vacuum advance cans here.

Since, the northstar is computer controlled, those things that I mentioned about distributor components will not apply BUT my tinkering with these items in the past has lead me to believe your rebuilt motor is not timed correctly.

The timing of the cams in relation to the crankshaft will have an effect on power output. The computer is looking for the camshaft at a "particular" time to fire the spark and spray the fuel.

The map sensor via vacuum "senses" load on the engine so that the calculate how much more advance or how little advance is needed.

The knock sensor IF working will pick up the pinging and retard the timing.

Yet, if not working or not connected, a code should be present.

If your tailpipes stay black, your vehicle is running excessively rich. The excessively rich mixture is washing the cylinder wall lubrication off, raising oil consumption.

The rich mixture is diluting your oil and lowering film strength for your bearings

The rich mixture is eventually going to ruin the catalytic converter.

The rich mixture will eventually foul your plugs and O2 sensors.

I'd like to be wrong, but I think your mechanic fubared the timing on that motor.

----------

I'm glad you cleaned the egr passage, but plenty of cars have ran with egr blocked off or bypassed completely.

I hope that solved the problem, but let's look at this?

How did the passage get so loaded up in the first place?

Running rich........

----------

As long as the car is running rich, that problem will resurface......

Ranger
08-14-14, 10:08 AM
I was spraying some carb cleaner around earlier and thought I heard some suction near the front of the manifold (bank 2). It was not accompanied by an increase in idle, so I can't say for sure.
Carb cleaner sucked into a vacuum leak will raise the RPM. If it didn't, there was no leak.

Joey_Italiano
08-18-14, 09:15 AM
Thanks, Eldo.

I follow your logic. I just wonder why this is happening now, 40K miles after the rebuild.

If they fubared the timing, I should have known about it then, right? Also, aren't there crank and cam position sensors that would throw a code or something? How do I check timing?

So this weekend I checked fuel pressure - 41 key on, 40 at idle. FPR is working.

I also checked compression (6 cranks, dry, WOT)

Bank 1
1 - 195
3 - 200
5 - 180
7 - 190
Avg. - 190

Bank 2
2 - 180
4 - 175
6 - 190
8 - 185
Avg. - 182.5

Pretty good, average is a little lower on Bank 2, but nothing crazy.

Changed the plugs (which were gross, but not totally fouled). Cleaned the MAF. Also changed the bank 2 O2 sensor, it was pretty crusty but the brand new one is still throwing a code anyway. Cleaned the idle control valve and its mounting hole (carefully).

Tightened down intake manifold bolts to 79 in/lb. (They were at 50 or so, so I snugged them up to spec, with the proper pattern).

Reset the computer and the "P0174" code came back after two drive cycles. The code is only "CURRENT" at idle. If I'm cruising, it goes to "HISTORY", but the light stays on.

Runs fine, great fuel mileage on the highway. Just the lean code at idle.

98eldo32v
08-18-14, 09:36 AM
The timing could be close, but not perfect.

I agree, it should throw a code.

Bank 2, P0174 is running lean......your problem may not be intake manifold related but possibly EXHAUST manifold or exhaust system related.

Check for exhaust leaks at manifold, 02 sensors, etc.

That 175 psi at cylinder 4, I don't like that.........

Submariner409
08-18-14, 10:04 AM
The 175 is still within the 10% cylinder-to-cylinder allowable.

98eldo32v
08-18-14, 02:40 PM
Understandable, but that's the bank that is also running lean........

Now that I look at the numbers again, I don't like cylinder number 5 either..........

I really don't want to say that a p0171 will be next followed by p0300.

I really hope to be wrong........

Check your map sensor for a possible vacuum leak, check the map sensor seal for integrity.

Joey_Italiano
08-18-14, 09:00 PM
Good news, everybody - I found the vacuum leak. It cost me $6. I smoked a Marlboro and exhaled it into the pcv vacuum tube with the engine off. Smoke poured out of the top fitting of the egr tube I just cleaned.

I bolted it down a bit better but the steel screw is really stripping out the aluminum throttle egr port spacer thing or whatever it is called (what is it called? I might need a new one - that or I tap it/helicoil it. It is the part the throttle body is bolted to before the plastic intake). What's with GM and mating aluminum with steel fasteners?

Anyway, had another cig and puffed into the pcv vacuum tube. All better, for now. If I mess with it again, it will strip for good.

No codes, running like a clock!

Ranger
08-18-14, 09:03 PM
Just use the next large size screw with the same thread pitch.

Joey_Italiano
08-25-14, 08:44 AM
Couldn't find a bolt between M8 1.25 and M10 1.0. I timeserted it by hand with a tap wrench. Little crooked, but that EGR tube ain't going nowhere!

Car is running great, no codes.

Just burning its usual qt/500 miles.

Thanks again for all your help, everyone.

Joey_Italiano
08-26-14, 10:12 AM
Can't resist...

So now that I'm out of the woods with that pinging and lean code, I'm still mighty curious about the oil consumption. I've done quite a bit of research on this forum, but I wonder what you guys think.

So, compression is good. Does this mean it's not the rings after all?

I noticed about 1/2 inch of oil in a couple of my spark plugs holes when I pulled them out (valve cover seals).

I also notice smoking when I punch the accelerator after coasting for a while, especially down hills. I've been told this was due to bad valve seals.

I also just smell the faint odor of oil smoke even at idle if the wind is blowing the right way.

I keep the engine oil at 7qts (typically drops to 6 in between adding) so I don't think it's the PCV.

Thoughts?

Ranger
08-26-14, 11:14 AM
Some oil consumption is normal. What is your consumption rate?
Have you read up on Oil Consumption in the Technical Archives in the black bar at the top of this page?

Submariner409
08-26-14, 11:30 AM
The oil in one or more plug wells is fairly common - the well seal O-rings weep over time - oil is an insulator, so not to worry there.

Oil smoke after long coastdown is usually rings, maybe valve stem seals. After sitting overnight, a decent puff on startup is valve stem seals........ a bitch of a job on a Northstar - and you might shudder if you have never had the cams off the heads - those 32 hydraulic cam follower buckets on the pre-2000 engines DO wear out.

Joey_Italiano
08-26-14, 11:39 AM
1qt every 400 or 500 miles.

Yeah, I've read them up and down and tried WOT and decarb procedure.

She's thirsty.

----------


Oil smoke after long coastdown is usually rings, maybe valve stem seals. After sitting overnight, a decent puff on startup is valve stem seals.

So sounds like my rebuild guy screwed up. Hey, I'll drive it until it blows up. Just keep the EGR clean and filling the oil.

I'll probably have to "fix" the catalytic converters some day when the get fouled.


and you might shudder if you have never had the cams off the heads - those 32 hydraulic cam follower buckets on the pre-2000 engines DO wear out.

That block will not be cracked again unless it's in the crusher at the junk yard.

Honestly, I've been thinking about the STS-V. 469 HP?!! What?! :bighead:

Submariner409
08-26-14, 11:47 AM
That level of oil consumption points directly at the second piston rings (compression/scraper) being installed upside down - they are tapered rings and must be installed with the stamped dot uppermost. Upside down, they make a most efficient oil pump - straight into the combustion chamber.

Joey_Italiano
08-26-14, 11:56 AM
That level of oil consumption points directly at the second piston rings (compression/scraper) being installed upside down

Unbelievable how much stress this guy's 10 minute mistake caused me after all the money I paid him.

The thing that gets me is they advertise as a specialist and their lot was full of northstar caddies. God know how many any other engines he did this to.

The sad truth is, it's cheaper to just add oil then have that thing rebuilt again.

$5 for oil every 500 miles, even if I keep the car for 100,000 more miles, that's $1,000.00. Buy oil stock, gentlemen!

Ranger
08-26-14, 02:55 PM
1qt every 400 or 500 miles.

Holy smoke Batman! That's some serious consumption.

Joey_Italiano
08-27-14, 08:26 AM
Holy smoke Batman! That's some serious consumption.

243082

98eldo32v
08-27-14, 09:49 AM
Have the mechanic redo that motor.......