: Northstar 4.6 Coolant loss - but only under load



pteeson
08-02-08, 01:33 PM
I have a couple of questions that I would appreciate answers to. Really would appreciate a scientific explanation of why no coolant loss in city driving but there is loss under heavy load. The full details follow for those who have the patience to read. The questions are at the bottom of the memo.

I have a 99 DeVille with 86,000+ kms. Last summer, every 1 - 1.5 months kept getting "Check Coolant Level" in the OBD. So I just topped up about 2 litres and kept on driving - 99% in the city. During the winter no need to top up.

This year again got the message as soon as we had to use the AC. Took a drive to visit my brother-in-law, about 60kms, and to get there we had to climb a hill on the highway that is about a 1 in 4 rise for about 1km.

Got a warning on the OBD "Coolant over temperature. Turn A/C off".
Checked the coolant temp and it was 128C so immediately pulled off and let it cool down. Only time it's ever happened.

Got to brother-in-laws and had to top up with water as had no coolant in trunk. Drove home safely with temp ranging from 88C - to 106C. It was mainly downhill.

So I Googled and found this site and discovered threads about Thermagasket.
Read up about symptoms, went to mechanic, did CO2 testing in coolant, checked for "smoke" from exhaust (none), water in oil (no evidence). Did not to compression test on cylinders.

CO2 test was inconclusive. But had very rough idle on startup for a minute or two. Mechanic told me to trade it in as it was likely a blown head gasket and not worth the cost to repair. Black book value for the car is around $5,000 (it's clean).

Decided to try Thermagasket (but was skeptical of a "mechanic in a bottle").
Anyway it seemed to have done something because no more rough idle on startup and no more coolant loss. But this was all city driving with the AC on.

Then came the acid test - another trip to my brother-in-law. Watched the temp and it was fine as we climbed the hill. But it then started to get hotter and when it got to 114C I got the "Check Coolant Level" on the OBD.

I pulled over, about 1km from my brother-in-laws place, let it cool down and topped up with water, about 2 litres (I had still not flushed the Thermagasket) and drove to his house.

Drove home OK and have been driving around the city with the temp holding pretty solid between 88C and 91C with the occasional high of 106C.

So here are my questions:
(0) Why would I get more rapid coolant loss when the engine is under load (e.g. 4 adults, AC on, 1 in 4 hill climb on highway) than I would in normal city driving?

Surely the metal expansion of the block and headers etc would have all settled down after she was warmed up?

What does the load do to make the coolant be lost and a subsequent temp rise?

(1) There is a recommendation, by rxAuto the vendors ofThermagasket, that I insert an adjustable themostat between the rad fans and the present control so that I can force the fans to come on sooner i.e. around 83C to 88C rather than the present Caddy ones of 99C to 105C.

Clearly the engine temp and hence the coolant temp has something to do with the coolant loss. But various comments in these threads have said the engine is designed to run hot.

So exactly what are the fan stages? Off, Low, High? Or are there more?
And at what temps do they begin to operate for each stage? Finally is there a way to program these settings using the OBD - II or are they hard wired.

Note: I'm 70 and no longer have the tools or place to do the HG replacement and the timesert thing for the block. And it really is not worth paying to have it done. So I'm thinking of just driving it in the city for another year or so and then moving on to a smaller car.

TIA for your expert advice for this old geezer....

respect.....

Peter

Submariner409
08-02-08, 03:54 PM
My Centigrade conversion is a bit lousy, so here's the data in F.

The thermostat is set to begin at 188 degrees and be fully open at 206.
The fans (without A/C) go to slow at 224 and fast at 236.
Both fans run in slow at all times when an A/C function is set on the climate control.

Earlier Northstars are prone to developing loose head bolts for several reasons, leading to loss of clamping pressure around some portion of the cylinder head gasket. This loss of clamping pressure leads to microscopic lifting of the cylinder head under heat and load thus blowing exhaust/cylinder gasses into the coolant jacket. This overpressurizes the system leading to coolant loss and subsequent overheating.

If the car has only ~54,000 miles and is in good to excellent condition otherwise, I'd go ahead and do the engine top overhaul.

Forcing the fans to come on at a lower than design temperature interacts with other engine and emissions sensors and leads to further degradation in performance. There's a school that espouses running an engine at 140-160 degrees for some sort of perceived performance gains. Nothing could be further from the truth. An engine should run at design temperatures, and cool oil is an incredible parasitic drag on engine internals, not to mention that the oil then never heats up enough to clean itself of vapor and acids.

Ranger
08-02-08, 05:37 PM
Sub pretty much said it all Peter. Sure sounds like the head gasket. No repair in a bottle will work for very long. You can nurse it for a while, but it will slowly get worse until you are forced to do something.

pteeson
08-02-08, 09:10 PM
Thanks guys. I have to admit it would hurt to get rid of her. She is in almost virgin state otherwise.

Guess I'll check out a place I found here that does quality remans on different autos. It's a machine shop but I don't know enough about them yet. I don't trust the dealer's mechanics to be caring or fussy enough to do a great job. Heck the dealership never even asked me to do a flush after 5 years for goodness sake.

From what Submariner said it's the heat generated by the load that's causing the bolts to pull a bit. In which case it has to be inserts and new bolts. Plus whatever other bits need replacing. I'll shop around and get some prices. Likely less than the cost of trading her and and getting some Japanese thing.

OTOH what if it's a honeycomb block kind of issue? Sort of scary thought.

Anyway I think I am safe driving her in the city for now and through the winter so I have the time to do some research. Pity I don't have the environment to do it myself. In days gone by I was part of a racing team, as a hobby, and we built one to race at Mosport. So it would make a nice winter project. But there ya go - can't stop old man time.

Sigh... respect.....

Peter

Submariner409
08-02-08, 10:08 PM
It's not a honeycomb block issue.......The sequence is open to debate, but consensus says that coolant gets into the head bolt reliefs and threads and, in conjunction with exhaust gas and acids, causes thread damage leading to bolt "pulling". Once the bolt(s) is slightly compromised, the extra combustion pressures and heat caused by load lifts the head and allows exhaust gasses to enter the cooloant. There's usually still enough clamping pressure to keep coolant out of the oil/cylinder in some cases. It's all case sensitive.

If you're going to go ahead with a top overhaul later, spend the $$$ and get a real Factory Service Manual from www.helminc.com (http://www.helminc.com). Your shop will appreciate the info. ........and know that the lower end of a Northstar is practically bulletproof, so there's no need for a complete teardown. Use the Norm's Insert kit and the thing will run forever. If you're a racer, appreciate the fact that the main bearing stud girdle is already in place.......

pteeson
08-03-08, 11:32 AM
Thanks for your reply Submariner. I've been thinking though and don't understand the physics here. If the threads are damaged and the bolts have pulled I can't figure out why it doesn't leak all the time and how the bolts could possibly tighten themselves when it cools down.

Or are they not tightened on cool down? IAC it seems to me that the heat generated by the engine under load must be expanding the head at a different rate than the block and thus maybe warping the head a bit and it returns to a normal structure when cooled down.

Anyway I'm going to talk to the machine shop here and see what they have to say. Once I get an idea of the price I can make a decision.

Looking under the hood it seems to me they would have to drop the engine out to get at the rear head to work on it. And on another thread someone said they have to drop the cradle first and then work on the engine.

Anyway I'll do a bit more research. If I can get away with $3,500 - $4,000 and I get a good warranty on the repair I might go for it. As I said she's in top condition apart from this issue.

As to racing her - never have and never would! I did my racing years ago with purpose built car. This is my dream machine for my age and I had hoped she would last till they buried me in her (grin).

respect....

Peter

misfit6794
08-03-08, 01:12 PM
Yes, the entire front subframe gets dropped, so its a really good time to do any other repairs that would otherwise be a pain, also make sure they timesert the block.

Ranger
08-03-08, 04:32 PM
peter, it sounds like it is in the early stages. The leak is very minor and that is why the overheating in occasional. The threads are not completely pulled. Most likely only 1 or 2 are starting to pull and are loosing some of it's clamping force.

tateos
08-04-08, 03:02 PM
peter, it sounds like it is in the early stages. The leak is very minor and that is why the overheating in occasional. The threads are not completely pulled. Most likely only 1 or 2 are starting to pull and are loosing some of it's clamping force.

Ranger is right - you still have some clamping from the adjoining bolts. Combustion pressure is not enough to leak past the gasket at low engine loads, but that pressure increases as you step on the throttle.

I know you said you will not be doing the work, but if you have someone competent do the repair, following the procedures we have outlined on this site, you will have a dependable engine for a long time (can't comment on the rest of the car). In the end, it really depends on how much you like the car, but if the car is in otherwise good shape, it will be a shame to get rid of it.

pteeson
08-26-08, 10:32 AM
Well the time has come to face reality. I am going to have a re-manufactured engine put in. We have a machine shop here that specialises in reman engines and has been in business since 1965 and they do the work for all kinds of dealers. I went and visited them yesterday with my brother-in-law and they gave me simple and straight forward answers to all my questions.

Cost is $4,500 for the engine and $1,000 for the install. Of course the government adds 13% tax so for around $6,215 I get a new engine. They will use my existing block and use Timesert inserts but not the ones from the kit. They use a longer one with Imperial threads and also thicker head bolts that can hold torque up to 70-90lbs.

The shop is run by 3 brothers and I spoke to the one who will do the actual work. Takes about a week and they have it down to a mini assembly line operation. Couple of mechanics remove the engine. Another person disassembles and cleans. Another machines it, grinds valves etc etc. Another reassembles including new parts for pistons, rings, etc. All together a serious shop. They warranty it for 3 years or 60,000kms. They have done lots of them. And not only Caddies but all makes.

So that ends this story. In my case Thermagasket did not work as advertised.
I fall into the 15% they say fail. Which is disappointing in one way because my car has not been abused - less that 87,000KM (< 54,000miles).

OTOH I get a new engine and since the car is in excellent shape in all other aspects I expect to be able to keep her for the next 10 years (or thereabouts).

Thanks for your advice and

respect....

Peter

zonie77
08-26-08, 12:25 PM
This guy isn't that far from you.

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/147522-headgasket-fix-1250-a.html

Submariner409
08-26-08, 12:58 PM
pteeson, If you do go with your local machine shop, try to be on hand when they pull the heads off and take a hard look at the condition of the bolts themselves and also the condition of the bolt holes. That would be good information to post.

Good Luck, but sorry that the head gaskets were, in fact, the problem. At least now the engine will run forever. Curious about the head bolt inserts....you could almost go to studs with longer thread lengths. Don't know if the heads themselves would allow studs........

Ranger
08-26-08, 04:47 PM
So that ends this story. In my case Thermagasket did not work as advertised.
I fall into the 15% they say fail.
Don't feel to badly Pete. On the Northstar you fall into 99% that fail. That probably represents their 15%.

pteeson
08-26-08, 05:00 PM
Thanks for the encouragement guys. I visited them yesterday and based on what I saw and the discussions I had, plus checking the BBB and other sources I feel confident. They must as well with a 3 year 55,000mile full warranty coverage. I asked them how many they repaired under warranty and they said 2-3 % and it was mostly small leaks not bolt failures.

Plan is to get this done some time around 8 Sep and I'll let you know.
It's not just a rebuild but a proper re-manufacture.

For those who might be interested here is their web site:
<http://www.crosstownengines.com/?gclid=COKX5dzB8JQCFRqiQQodKUMVqw>

Also note this from my earlier post:
"They will use my existing block and use Timesert inserts but not the ones from the kit. They use a longer one with Imperial threads and also thicker head bolts that can hold torque up to 70-90lbs."

Anyway expect to hear from me as things progress.

respect...

Peter

tateos
08-26-08, 07:36 PM
Looks like a pretty good place

alexo1us
08-27-08, 10:17 PM
I would check alittle further if the gaskets on are blown it mabe early enough just get them replaced or take a ride to that guy in tillisonburg stay overnight get it done for 1250 great ride in the fall.
hell for that price take it to him anyway you may even get a discount if the bolts are still fine
I doubt I would go for a total rebuild since my understanding is the rest of the motor is bullet proof.
As for crosstown I have been in this city for years and have heard some bad things about crosstown but I did hear around that time you mention 85 there was a owner or managment change, so the new guys may be better but for 6000 plus your still just getting a rebult engine using anything that was on your motor that is still good.
whats a new northstar worth?
Sounds like your engine at the worse needs h/g and bolts that job can be done all day long for less then 3-4,000 even less if you look around.

pteeson
09-03-08, 12:50 PM
I thought I would just keep y'all up to date.

Firstly wrt Crosstown Engine Remanufacturing. I have checked them out, including 2 auto repair shops and 2 individuals as well as the BBB.
They have an excellent and enviable reputation - the sort I hope people would give about me when I was working as a freelance software developer.That confirms our impression after we visited their shop and spoke with them. They answered us very straight forwardly. (see my earlier post)So on Monday 8th Sept we take her in for the reman. I don't know where alexo1us heard stuff but the facts I dug up do not support his rumour.

Secondly I contacted Thermagasket and explained that it didn't work in my case and they have authorized a refund, exclusive of shipping. It should appear on my CC within 60 days. So they lived up to their word. Ranger perhaps it works on other engines just not as well on the Northstar. Of course for the Northstar the long term solution is inserts and head gaskets.

It's going to take about a week for the reman and when I get her back I'll let you all know how things work out by posting here from time to time.We have a 2 hour one way highway trip coming up in October so that'll give us a good chance to bed her in. It's gonna be like a new engine so no extended same speed distance; just vary it as appropriate to get an good bedding.

Finally wrt to the guy in Woodstock pointed to by zonie77, it's too far away and just not worth the risk with an unproven, IMHO, long term track record.I'll go with the reman and expect to get at least 6 years out of it.Maybe more as I only do 10,000kms a year these days.

Meanwhile thanks for your advice guys and I'll be talking with you from time to time.

respect....

Peter

pteeson
09-16-08, 03:21 PM
Well I picked her up today after the engine re-manufacture. Here's what they did; took it right down to the bare block, rebored the cyclinders, new pistons and rings (oversize of course), reground the valves and seats, new lifters, all timing gears,chains, as needed, reground and balanced the crank, new bearings, new oil and water pump, made sure the rad is ok, etc. All of the above is standard for any engine the rebuild.

And the most important part trued the head and did the inserts and new bolts. They used Timesert inserts but not the ones from the kit. They used imperial threads and longer inserts and bolts and special pressing to the block.

New plugs and ignition wires and the new head gasket is the revised one from GM. So now I have a "better than new" engine that I have to break in.

There is a "service engine soon" light that stays on and has a rough idle and they told me about it and they've looked into it. Soon as you accelerate the engine purrs.

They want me to drive it for 1,000 - 2,000 KM because they think it's maybe dirty injectors or a malfunctioning sensor. Maybe a result of the fluids from the blown head gasket. In their experience they say it will go away by itself 9 times out of 10. But if not bring it in and they will sort it out. It's under warranty anyway for 3 years or 60,000KM.

They also did the front brakes, new rotors and pads but I don't mind that since they have never been done in the 86,700KM (53,000+) miles so were due anyway.

So the total cost was $7,500 of which $870 is government taxes - welcome to Canada! But I'm OK with the cost because it's a lot less than a new car and now the engine should last me another 10 years by which time they might not let me drive anyway (we get re-tested when we're 80 every 2 years).
Besides the car is in great shape and is a decent size for a big guy like me; not like these so called full size things they make these days.

So I'm off to put on some kms on her and see how things pan out. From time to time I'll report back here. So although I gave Thermagasket a shot it just isn't going to work if you have the corroded headbolt threads problem and have blown your gasket. If you have this issue you need to decide whether you're going to do a proper job or just trade her. In my case I decided to do a full re-manufacture and keep the car. You might decide to go with just the inserts.

respect

Peter

Ranger
09-16-08, 04:46 PM
Congrats Pete. Keep us updated.

pteeson
09-17-08, 03:13 PM
P.S. Today, Wednesday, we decided to go for a spin to Niagara on the Lake to put a few kms on her.
So we're tooling along the 407 and just before we get to Woodbine we get a display on the console.
"Low refrigerant - AC Off". Gave them a call and they said come on down.

So we went there and they tried refilling but to cut a long story short they eventually took it to their AC specialist.
(They only do engines and sometimes brakes as in my case).
Anyway the AC guy said they have a leak and please make an appointment to bring her in. They'll call me later today.
I confirmed that it's covered under warranty anyway. Probably a hose leak or a loose clamp or something. No big deal and understandable bearing in mind what you have to do to get the engine out. At least they're doing the right thing.

tateos
09-17-08, 05:30 PM
The AC hoses frequently get damaged and leak when the front engine mount failes and allows the engine to rock and stress the hoses more than normal. On my '97 ETC, the entire assembly is one part and is called a "manifold" - input and output and the aluminum block and fittings that mount to the compressor

pteeson
09-22-08, 10:12 PM
Thanks for the thought tateos but the engine mounts were checked before re-installation. I took her in this morning so they could send her over to their AC specialist. He found a leak in one of the pipes that had got crimped somewhere along the way when they removed and re-installed the engine. Anyway had to order the part which is coming in tomorrow and the repair will be completed. Hopefully that's going to be it.

Looking forward to taking a few longish drives, ~400KM's, to see if the idle roughness goes away. It's a nice time of year anyway - Fall with the leaves starting to turn. Might take a run up North a bit to have a look.

Stay tuned as the story continues.

Peter

mtgldr
09-25-08, 08:04 PM
Please keep posting as the journey continues

pteeson
09-25-08, 09:05 PM
Well the AC problem has been fixed under warranty. Picked her up on Tuesday. Wednesday took her for a 120KM spin and today did 400KM. So now have got 700KM since the rebuild.

But there is still a LOT of misfiring at low rpm. When I picked her up the first time after the rebuild they warned me that the "Service engine soon" light would be on and that there was this rough idle and misfires at low revs. "Drive her for 1000 - 2000 KM and 98% of the time it will correct itself" is what they told me. When I asked why a brand new car from GM doesn't have this problem they said that GM has better tools to configure the computer and now the computer "needs to relearn the engine now that it's been rebored". I was sceptical about this but they told me that it happens all the time with rebuilts.

I went to a NAPA store and bought another bottle of the Lucas injector cleaner, as they advised (they had put one in before delivery). Dumped that in today before the 400KM drive and filled up with Sunoco 94 Octane just to give her the best juice. At highway speeds she seems OK but at low revs it is a disgrace - it just should not be that way.

I discussed this with two different people; the guy in the NAPA store who says that it happens all the time - they get lots of people who have modded and they often tell him the same story. He said it should go away "after 3 cycles" which I think meant 3 days of driving. The other person was the emission testing place. (We have to get a clear report before our plate licence is renewed and mine is due 1 Oct). He refused to do the test if the "Service engine light" was on since it would fail. But he said he had read about this as well.

I am still sceptical. Why can't they just set the parameters to whatever are the correct values and be done with it? I wish there was somewhere I could read up about this. As a retired software developer I think I could understand what the computer is supposed to do, with a little bit of reading. I did display the OBD-II codes but not in full detail. I want to get a printout of them and will be asking if they can give me that.

Tomorrow I'm going to put some more KMs on her and hope to get to 1000 to see if it does resolve itself. But I'm not holding my breath. However I just have to get them to make it right to pass the emission test or else I don't get to drive with legitimate plates - i.e. with renewed plate licence. It's under warranty anyway and they are nice people so right now I still have confidence. They said they will look into things if it doesn't self heal.

I'm going to try searching in the forums here in case others have had a similar problem. Sure would be comforting to know if that is so and how they dealt with it.

respect....

Peter

Ranger
09-25-08, 09:23 PM
I don't know Pete. I'm skeptical. Have you pulled the codes?

Mark C
09-25-08, 10:20 PM
One or more of your cam gears are probably off a tooth. That will give you a rough idle, and its real easy to do if your not triple checking the timing when the chains go back on.

pteeson
09-26-08, 11:40 AM
Well I just read out the OBD-II codes. Here they are:

DTC Codes as of Friday 26 Sept 2008 - 700KM driven since rebuild.

PCM Codes
Current
P0300 - Engine Misfire Detected

History
P0103 - Mass Air Flow (MAF) Sensor Circuit High Frequency
P0106 - Manifold Absolute Pressure (MAP) System Performance
P0123 - Throttle Position (TP) Sensor Circuit High Voltage
P0134 - Heated Oxygen Sensor (HO2S) Circuit Insufficient Activity Bank 1
Sensor 1
P0202 - Injector 2 Control Circuit
P0206 - Injector 6 Control Circuit
P0207 - Injector 7 Control Circuit
P0208 - Injector 8 Control Circuit
P0372 - IC 24X Reference Circuit Missing Pulses
P0461 - Fuel Level Sensor Performance
P0603 - Control Module Long Term Memory Reset
P0758 - 2-3 Shift Solenoid Circuit Electrical
P1107 - Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low
Voltage
P1121 - Throttle Position (TP) Sensor Circuit Intermittent High Voltage
P1323 - IC 24X Reference Circuit Low Frequency
P1370 - IC 4X Reference Circuit Too Many Pulses
P1644 - Traction Control Delivered Torque Output Circuit
P1645 - Evaporative Emission (EVAP) Vent Solenoid Contorl Circuit
P1646 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit
P1650 - Control Module Output B Circuit
P1860 - TCC PWM Solenoid Circuit Electrical

Also IPC B1552 History
PZM B1552 History
RFA U1000 History

My guess is that the History codes are from when they restarted her after the rebuild. Can anyone confirm this? The only current code is 300 and that means "Misfire detected". We knew that anyway.

On Monday I have an appointment to take her in and let them have a look. Between now and then I'll put on another 300KM so she has the full 1,000 they wanted.

respect....

Peter

Ranger
09-26-08, 05:11 PM
YIKES! That's a LOT of codes. I had a shit load of them when I had my car in for a warranty job (window regulator) and the battery went dead. I wonder if those are not from pulling battery power or something similar. I'd clear them and see what returns.

pteeson
09-26-08, 07:39 PM
Removing all power, i.e. disconnecting the battery, will reset all things. The next time you return power and start the engine it will go through some part of the GM Driving Cycle. That's what I think happened for the codes that are marked History. On Monday they get her back to work on. After they've fixed things I will clear all codes and start fresh to see what pops up, if anything.

Here are a couple of URL's that will give you more information.
http://myweb.accessus.net/~090/dtcobd2.html and
http://myweb.accessus.net/~090/cadidiag.html#ses

respect...

Peter

pteeson
10-02-08, 04:08 PM
You are absolutely not going to believe this. They have found the problem! If I were a betting man I would offer you a challenge. But since I'm not, spare a moment to think about what it could be?

It wasn't the timing chains - they went to the trouble of taking off the cover and looking at them- they were perfect. It wasn't the computer. But it WAS in the electrical system. One of the things they replaced with new parts were the ignition wires. Delco factory replacement ignition wires. Never been used. Brand new! $185 set of virgin ignition wires!

AND THEY WERE THE PROBLEM! ARRRRRRGGGGGGGGGGHHHHHHHHHHH! Who would ever think that would be the cause! Unnnnbelievable! Replaced them with a new set and she purrs like a kitten and growls like a tiger. Anyway they did find a noise in the exhaust system and they are replacing a gasket. So I should get her back this evening.

I mean this is far too stressful for an old man..... this is no "country" for me.

So all's well that ends well.... PTL who watches over us all. Keep the faith!

respect.....

Peter

Playdrv4me
10-02-08, 04:43 PM
All those repairs have probably exceeded the vehicle's value but it did have low miles and new (and used) cars are probably hella expensive in Canada. Hope it lasts along time (not sure of the value of the different timeserts though).

Submariner409
10-02-08, 04:58 PM
I'd be willing to bet more than even money that the new wires were connected to the wrong coil towers. Your car uses a waste spark system in which 4 coils fire 8 spark plugs. 2 plugs fire at the same time, one on the proper advance for the compression cylinder, the other at the same advance, but in the exhaust cylinder 180 degrees from the power cylinder. In the timing sequence the power plug fires on the positive voltage side of the coil, while the waste plug fires on the negative. Reverse the plug wires and you get a weak spark on the power stroke which leads to poor performance.

Do a check for yourself. Click on the diagram and scroll in. Google "waste spark ignition general motors".

Playdrv4me
10-02-08, 05:20 PM
I'd be willing to bet more than even money that the new wires were connected to the wrong coil towers. Your car uses a waste spark system in which 4 coils fire 8 spark plugs. 2 plugs fire at the same time, one on the proper advance for the compression cylinder, the other at the same advance, but in the exhaust cylinder 180 degrees from the power cylinder. In the timing sequence the power plug fires on the positive voltage side of the coil, while the waste plug fires on the negative. Reverse the plug wires and you get a weak spark on the power stroke which leads to poor performance.

Do a check for yourself. Click on the diagram and scroll in. Google "waste spark ignition general motors".

That's excellent info. I'll have to remember to bookmark this if I ever have any stutter or spark issues in the future with my N*s.

Submariner409
10-02-08, 05:41 PM
Only for the pre-2000's. After that the individual 4-coil cassettes and boots are another can of worms and those 2 diagrams are meaningless. It's all magic then........

pteeson
10-10-08, 09:06 PM
Nope the actual wires were arcing. They were defective. It was only at idle RPM that there was misfiring. Anyway to continue the saga. I drove her home and as is my custom I roved through the DIC and looked at the various values. The battery volts were down to 11.6 and falling as I drove home. Plus my wife first smelled a burning smell and as we checked further there was some sort of squealing sound. Not at all what I had expected.

So I sent them an email and said that I thought there was a failed or failing alternator. It was 9 years old so I wasn't too upset. But I told them they would have to tow it as the grinding sound seemed like metal on metal which together with the burning smell made me decide not to drive her.They eventually came and took her on Monday morning this week and changed the alternator along with 2 tensioners and the belt all under warranty. That improved it but the sqeuealing sound, although diminished, was not totally gone.

They discussed it with the AC specialist they use, the one who found the pipe leak, and he said right away that he knew what it was. Apparently there is a shim of some sort that sometimes gets pushed in too far and causes the squealing. He couldn't get to it till Wednesday which he did. They covered this under warranty as well so they are honourable people. But they kept the car for the rest of Wednesday because they wanted to put some kms on her before letting me have her back. I think they were a bit embarassed and wanted to make 100% sure. They picked me up on Thursday morning and I paid for the reman alternator and have been driving her since. Really feels like she used to be but it's early days yet.

All the DIC values are in range and I checked the OBD-II values and there was nothing of much interest there. So this afternoon I cleared them and will drive around over this Canadian Thanksgiving long weekend. Tuesday morning she goes in to my regular mechanic and I'll have him go over her from stem to gudgeon plus I want to see if we can use the rollers at the emission test place to put her through a GM Drive Cycle and see what pops up. But my seat of the pants feel when driving her is that she's back to 100%.

respect... Peter

P.S. As to the value of the car vs what I spent on her. Sure it doesn't make economic sense if I were a younger man. But I'm 71 now and the car is in superb shape other than the original engine problem. It's a decent sized car for a 6'2" guy and she rides just great on the highway. If I get 10 years out of her, which I expect to do now, then it's not such a bad deal versus 30 grand for a new small rinky dink thing they make these days. But that's just me.

Submariner409
10-10-08, 09:51 PM
Lots of money, time, and frustration. You're fortunate that the shop didn't wash their hands weeks ago. A 6-pack or so of Boddington's would be in order for the mechanics. :rolleyes: Now drive the car and stop toggling the DIC...

Destroyer
10-10-08, 11:36 PM
$7500!?:eek::alchi:

pteeson
10-12-08, 10:46 AM
How do you know about Boddingtons? Were you there in the 40's?

Well you're correct that I am lucky having such an honourable company doing what's right. They have such a good reputation and I think they felt embarrased that I was having trouble. Especially since I had to miss a wedding because they had her for service.

As to the alternator I willing forked over for a reman one. They gave me a break on the labour. As to toggling the DIC I only do that after she has been in for service or if there is a reason to do so in normal driving. That's what the information is there for. I'm not obsessive about it.

IMHO a good auto mechanic is part scientist and part artist. The DIC is for the science side of things. Your ears and hands are for the artist side.

As to the $8,000 I spent remember that $450 was for the alternator and $650 for front rotors and pads. That would have come up sooner or later anyway. So the $6,200 for the rebuild is not that wicked give all the new parts. And the balance was government taxes.

So peace to all our American friends and good luck in your election and the following Thanksgiving. This probably puts this thread into dormancy but from time to time I might drop back and do an update.

Thanks for all the comments and advice....

respect....

Peter

pteeson
10-28-08, 09:26 PM
Well she seems to finally be back to prime condition. My own mech discovered that I needed to do the rear brakes, rotors and pads. I think the mech at Crosstown just did not check them, as I had asked, so when they reported to me that they were 65% they were misinformed. Also the mysterious grinding sound turned out to be the AC clutch which was badly scored and scraping when the AC was not engaged. So I replaced that and things seems to be fine now.

So to look at the big picture: engine reman, brakes all around (1st time since I bought her), new alternator, new AC clutch. I can't complain since, other than the engine reman, those are reasonable wear and tear items after 9 years. Total cost $8,800 including taxes. I figure to get another 10 years out of her and if I do then it will not have been a bad investment. By then they may not let me drive although I hope to be able to.

I'll report back after I hit 5,000km and switch to synthetic oil.

Now I'm going to research how to mod the radio so I can hook up my iPod Nano. Be nice to just plug it in to an Aux input but the radio doesn't have that. Maybe I can use the tape input wires. Got to dig out the circuit diags from somewhere. Or I could use an FM transmitter on the iPod. Another little project to keep me busy.

Ranger
10-28-08, 09:42 PM
This is what I plan on using.
http://catalog.belkin.com/IWCatProductPage.process?Product_Id=153161