: 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!

----------


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?

----------

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.

----------

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?

----------

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.