hjb981

Hi again, major repairs on the '97 DeVille

30 posts in this topic

Hi - it has been a while. I have had very little time to think about car stuff lately - even Cadillac stuff. I got married, defended my PhD, got a job, bought a house (I finally have a garage :)), and very recently became a father. I still have the '97 DeVille, but it is now in need of some major renovations. There is oil going into the coolant (luckily not the other way around), misfiring, increased fuel consumption, high carbon monoxide levels in the exhaust, coolant consumption and so on. I am guessing a blown head gasket - certainly not something "less bad" - either way the engine will have to come out of the car and be swapped or completely remanufactured. The car has 200000 miles on the odometer and the transaxle has shown some signs of aging, namely sporadically dropping and rising engine RPM:s when coasting in 3:rd gear (as if the transmission slipped, although only when coasting). Given the mileage and cost of R&R:ing the powertrain, I would change or have the transmission remanufactured as well if I did the engine, even if it was not showing any signs of strange behavior.

At the moment, the car sits in my garage and I have not actively started planning for repairs. Although it would be way more complicated than anything I have ever done on the car before, I would still have liked to do the work myself, but there is simply no way I can see that happening in the foreseeable future since I will not have the time. I do not want a ten-year dismounted car project...

Given that I live in Sweden, my options for remanufactured Northstar engines and transmissions are far more limited than for those of you that live in North America. I still do not know exactly what options are available. At least there is a shop that works on these cars in my area that I have used over the years for other things.

Any thoughts, recommendations or ideas?

/Jonas

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If you are getting oil in the coolant, but not overheating, the problem is probably the oil cooler in one of the radiator tanks, not a head gasket. Smell the inside of the surge tank; if you don't smell exhaust there, the problem is probably not the head gasket.

As far as the misfiring, emissions, and economy issues are concerned, that's a tune-up thing. Plugs, wires, water in the gas, etc. are possibilities. Most tune-up issues throw OBD codes, so the first thing to do is to run the codes and post them here.


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I would do a combustion by products test to see if you have a blown head gasket. Your mechanic may have a test kit for that purpose. But when my head gasket blew there was a distinct exhaust smell in the coolant tank. Determine that first so you know how to proceed.

Post your codes maybe your transmission problem is solenoid based.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

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You probably do have headgasket failure, all of your symptoms point to it. What is the condition of the car?

200k is nothing for one in good shape. My 96 had over 200k and still rode like new Unfortunately the torque converter and headgaskets went around the same time. Car was too rusty to repair, Not worth it.

Clean one I would absolutely fix, Wait I just did lol. I just bought and had the engine replaced in my new to me 97 De'elegance


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Oil in the coolant - If your car has an oil cooler in the radiator tank, that is what could be leaking. You can identify the radiator that has an engine oil cooler by inspecting the side tanks - both sides will have cooler lines - one side for the engine oil and one side for the transmission fluid. If there are only lines to one side, those will be the transmission oil lines.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I agree on the oil cooler part. If it was coolant in the oil it would be likely head problem, but oil in the coolant is usually oil cooler.

But your other symptoms point to another problem that sounds head related.

I have yet to see one that had the oil cooler. I think it was only available in the 300hp engine


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Yes I think the 300 hp engine had the oil cooler, although I could also see the 275 hp engine getting it with a tow package if it were available


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Jonas, I once sent a 4.9 engine to Amsterdam via DHL. If you need something I might be able to help


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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One thing to consider is that it could be transmission fluid in the coolant - that would look like oil also. If the car is not overheating, I would not suspect head gaskets at this point.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Good point kevin, that would explain the slipping.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks for all the encouragement :-). I bought this car in 2004 at around 85k in California. After driving it there for a couple of years, I shipped my rust-free California car to Sweden when I moved back. The first thing I did was a complete anti-corrosion treatment: corrosion protection inside of the under-body beams, inside of the doors, hood, trunk lid and then a complete covering of the outside of all the under-body parts. Although there is some small rust spots on one back door and some more rust on the very lower parts of the doors on one side of the car, the structural components should be fine. The rust on the door is just in the sheet metal and should be easy to fix. So the car is fine, and I am keeping it. The question is more what I will do and when.

The issue about oil in the coolant tank started a year and a half ago, and I actually drove about 40000 miles (I drove more than ever before in the last two years) after that started happening. Not ideal, but I never figured out exactly what was going on. There are pictures in this thread from back then: http://caddyinfo.ipbhost.com/index.php?showtopic=42997&hl=. One of the spark plugs have accumulated deposits since at least maybe six years - I always thought that was from oil leaking past a valve - and I mitigated the problem by changing that plug about once per year. The car does not have an oil cooler connected to the radiator (there is a small oil cooler in front of the radiator), but the transmission gets cooled by the radiator. A few years back, the radiator burst and I replaced it (hence I am very sure about the cooler lines) - something that could also come from a broken HG. The coolant system retains some pressure even when completely cold (and I have opened the radiator cap many times before the problem arose, so I am positive that what I see now is not normal behavior). There is some kind of smell in the coolant that may or may not be exhaust, but I have also smelled gasoline in it on several occasions, and that smell was very distinct and unmistakable. I guess the gasoline in the coolant comes from the overly rich fuel mixture (confirmed by the carbon monoxide value) bringing fuel to the coolant through some leak in a HG or elsewhere. It could also come from the misfire events.

The transmission does not slip under load. It only happens in third gear when coasting, say at 20-40 mph. If the RPM is held at for example 1000 rpm by the speed of the car, it could then suddenly drop to 600 or even 400 rpm for a second. It does not happen when the car idles. I think I had a previous thread on this, but I cannot find it at the moment.

BodybyFisher: thanks a lot for the offer to help! Do you know if it was possible to get that engine with some kind of warranty that was valid in Europe?

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High hydrocarbon values would be indicative of a leaking fuel injector or fuel pressure regulator.

Are you sure the transmission is slipping at low speeds? From the description, it sounds like the engine is stalling or a near stall condition. If the transmission was slipping, I would expect the RPM to rise significantly. If it is a stalling condition, it could be due to a sticking EGR valve or an idle air control solenoid that is sticking.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The engine normally idles at around 650 rpm, but when coasting with the engine doing 1000 rpm, the engine is being driven at a higher-than-idle speed by momentum of the car through the transmission. At some point, the fuel should even cut off completely (maybe around 1000 rpm, but that is just a guess). If the fuel is already cut off because the engine has reached the threshold speed for fuel cut-off when the accelerator pedal is not pressed, that could also explain why the engine speed dips below idle speed sometimes, although it is weird that the PCM does not catch it in time. Maybe the algorithm for re-enabling the fuel injectors is different if the PCM senses that the car is coasting in gear (and hence should have a very predictable engine speed. Since this rpm drop only happens when the engine is turned faster by the car's momentum, I cannot see how it has to do with the engine. I think it has to do with the fluid pressure in the transmission being the lowest when the engine is at low speeds and some clutch or band used for the third gear being a bit weak. There are no transmission codes and the transmission certainly does not slip in "the normal way" (i.e. under load). There is no coolant in the transmission fluid, and the level is neither too low nor to high.

If it was a bad solenoid the transmission should act up also under load, I suppose. A "normal person" would not notice the transmission thing, since it does not affect driveability in any noticeable way. I can hear the drop in engine speed because I am more attuned to how the engine should sound (even though you can barely hear it when the car i rolling and no throttle is applied) and obviously see it if I put on the rpm readout on the DIC.

Anyways, there is no way that I would R&R the engine without also doing the transmission and viscous converter clutch. Too much of the cost lies in the R&R, and the engine and transmission come out together.

And yes, there may be several problems with the engine. Tune-up related stuff, leaky injectors, fuel pressure regulator etc are additional possibilities. Although I did not say it outright, you are right that I also have high hydrocarbon values - although a leaky injector or fuel pressure regulator would not explain why hydrocarbons (gasoline) also would end up in the coolant.

I have been trying to figure this out for the last couple of years, including some forum discussions. The problem has just gotten worse to the point that something needs to be done. Unfortunately I really cannot see how this can be solved in any other way than taking out the power train. The oil and gasoline in the coolant is a bad sign.

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The small cooler in front of the A/C condenser and the radiator is a cooler for the power steering.

My 1997 ETC did have an oil cooler; the "T" in the middle of "ETC" means it comes with a VIN "9" engine, 300 hp. The Devilles did not come with the VIN "9" engine until the DTS, which was a couple of years later. The 8th digit of your VIN number will be a Y.

KHE's idea that the oil in the coolant could be transmission fluid is something you should look out for. Check the transmission fluid and if it shows milkiness or signs of water, then you need to get a new radiator and have the transmission flushed ASAP. In any case, you should have the transmission serviced every 50,000 miles or so if you plan on driving the car forever. Flush it with Dexron VI and that will double the life of the transmission. But don't wait to look a the transmission fluid because water can ruin a whole transmission very quickly.

The PCM is very good at controlling engine speed under all conditions. If you are having unstable engine speed near idle, the idle stepping motor is probably sticking or out of adjustment, the throttle body is dirty, or there is a vacuum leak or a problem with the air hose to the air cleaner.

Gasoline in the coolant??? Why do you think that there is gasoline in the coolant?


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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Aha, I did not know that the little cooler up front was for the power steering. Actually, the DeVille Concourse had the VIN 9 engine, different final drive ratio (3.79 instead of 3.11 if I remember correctly) and road sensing suspension (the one with magnetic particles in the dampers). It was after a quick drive in one of those that I decided to get a Northstar. :-)

I have considered the ATF possibility thoroughly and ruled it out, considering the following:

- Oil started appearing in the coolant 2.5 years ago. It has since continued to appear at a slowly increasing rate.

- I always keep track of the different fluids and have kept a very close eye on them for the last 2.5 years.

- The ATF has never shown any trace of milkiness or anything else. It continues to be clear red and looks the same as new ATF.

- The level of the ATF has not changed at all in any direction ever, including the last 2.5 years (even though I have emptied oil from the coolant reservoir several times).

- The radiator is the only possible pass-over point for coolant and ATF (right?). I replaced the radiator after it burst about 1.5 years ago. It did not alter the way in which oil appears in the coolant in any way. Oil kept appearing at the same rate after as before the radiator change. The old radiator had clear signs of overpressure (expanded coolant passages).

- The oil in the coolant has never had a trace of the red ATF color.

- The oil in the coolant looks and smells like engine oil (except for when it smells like gasoline, below).

- Sometimes, especially when opening the coolant reservoir and smelling it immediately (when cold, of course), it smells like gasoline. The gasoline smell in the coolant is very distinct and unmistakable. If I leave the radiator cap off for a while, the gasoline smell lessens and it smells more like engine oil and coolant (gasoline is much more easily evaporated than oil and glycol). I have also smelled gasoline in the engine oil (by smelling in the oil filler hole (I have smelled the oil several times before and I have not smelled that much of gasoline in it)). Under normal conditions, some gasoline in the oil is normal from blowby right after a cold start, but pretty quickly the oil heats up enough to evaporate it while the engine achieves more complete combustion and thus prevents further build-up of gasoline in the oil. This may be so little that it would not cause the oil to smell – I do not know. If the engine is running rich and also misfiring, accumulating gasoline in the oil could be expected (even if it also gets evaporated via the PCV and burned in the engine). If combustions gasses pass through to the coolant, I could see how gasoline could get in the coolant if both rich running and misfiring are present.

The idle speed does not fluctuate at any time when the engine is idling by itself. The only time when the engine speed behaves strangely is when coasting in third gear. Not in forth, second or first gear. Not when idling in neutral or park. I cannot see how a sticking idle speed motor could explain why the engine should drop so much when the engine is being turned by the cars momentum (although it could explain why the PCM is not able to recover the idle speed as it should, i.e. the occasional drop to 400 rmp). It also seems very odd that it would not happen in any other gear than third (fast coasting in forth gear gives the same engine speeds, but never any drops), if it was not caused by the transmission.

It is a good idea to actually test the coolant for combustion gasses. I have not done that.

I do not have the codes right now, but they are related to the rich running (the O2 sensors do not swing like they should) and misfiring (P0300). I will have a look and post them later, but they will unfortunately not help with the big problem (oil in coolant).

To make things weirder: over the last year or so, the engine has started running cooler and cooler, and now only reaches around 180 degrees F (not the normal 196 degrees F, which it always reached before). I have felt the engine with my hand, and it does feel less hot than before. It also takes longer for the engine to warm up. An idea of mine is that exhaust gasses leak into the coolant very close to the thermostat, which has led to it opening immediately and keeping the coolant temperature in check. Now, the thermostat may have been damaged and perhaps does not close like it should or opens too quickly. This is not the cause of any of the other problems, since all of them appeared long before the change in engine temperature (although it would make gasoline evaporation from the oil slower).

As always, thanks for the help and input!

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Do a combustion gas test in the coolant. You should likely find your answer. Drive it hard, carefully remove the cap, then test it. Mine failed instantly.

Given I had slightly different symptoms that yours, but I have run into the issues you have also


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You are right about the Concourse, it had a 300 hp engine along with the STS and ETC and most likely had the oil cooler.

Please post all P or powertrain codes or state OUTRIGHT that you do not have any P codes.

As Rock said, check the coolant for combustion by products, to answer a LOT of questions. You are not overheating from what I can see but a test at this point is necessary.

You should have then tranny and oil coolers checked, a good radiator shop can handle that.

If you have not done a good throttle body cleaning, clean it well, the throat, front, edges and back of the plate and remove the idle control solenoid and clean the pindle and port the port can get clogged. Its not an easy job to do, use carb cleaner on a rag, do not spray into the TB.

Are you getting O2 sensor codes?

Is the check engine light on?

When were the ignition wires and spark plugs replaced?

Please try to respond directly to my concerns and questions, long single paragraph types of replies aare tedius and hard to decipher. Think in terms of bullets, ignition, tranny, coolant, codes, etc, its easier to follow


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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If you have a VIN 9 engine, you have an oil cooler. I would still look at the possibility of a leak in the radiator oil cooler because there is no other credible path from the oil to the coolant.

I once had the stabilizer links changed on a 1997 Eldorado. The noise did not go away. A few months later, I had them changed again, and the ones that came out were the originals. The first mechanic had someone do the wrench work but somehow it didn't happen at all. The two of them probably mixed my car up with another car. This just might explain why your radiator still has an oil cooler leak, even with a used radiator to show for the work. AND, it takes a stuck radiator cap and massive overheating (think huge clouds of steam, blown hoses, stranded car) to blow the tubes in the core like they showed you on the used radiator.

If your car isn't warming up properly, it has a stuck thermostat, an incorrect thermostat for your car, or the thermostat is installed incorrectly and can't close properly.

The vacuum line from the FPR diaphragm, if the FPR is leaking, carries liquid gasoline into the intake manifold and it can sit on the pistons, leaking down into the oil. Only a huge, long-standing problem with the FPR will cause this kind of problem. An FPR is an inexpensive throw-away part and is easy to check - pull off the vacuum hose and if you smell gas, replace it.

The best place to smell the oil is on the dip stick, a few feet away from the engine so that the oil is all you are smelling.

The only credible way that I can think of for gas to get into the coolant is for the FPR leaking so badly that a whole lot of gas is in the cylinders when the car sits for awhile so that you have near hydrolock when you next start the car, pushing gas through the head gasket. That is really far-fetched and I have difficulty imagining that a such a car would be driveable. It certainly would be hard to start, particularly with a hot engine.

If you have RPM dither only in 3rd gear, perhaps the PRNDL switch needs adjusting. If it is a transmission solenoid, you will be getting OBD codes from that.

I would start by checking the FPR and, if it is leaking, change it. If so, changing the FPR and an oil change may get rid of most of your problems.

But gas in the coolant is a new one on me.


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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Must also mention that the thermostat may be missing ie not installed. Have seen that before in attempts to try to cover up larger problems, kind of think this is not the issue here though


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Sorry that this is so long again, but I have at least tried to use a bullet point format (each paragraph is a bullet point, just without the bullet in front).

I have a base DeVille and hence the VIN 9, 275 hp engine.

I am 100 % sure that I have a new radiator, since I order one from Rockauto and changed it myself.

I am 100 % sure that the engine oil circuit is not connected to the radiator since I changed the radiator myself and disconnected/connected all components myself.

The ATF that came out of the cooling passage in the radiator when I disconnected the ATF cooler lines from the old radiator was clear and red, like new ATF.

The spring-loaded pressure-holding part of the pressure cap moves freely.

Coolant (with oil) has passed the pressure-holding part of the pressure cap, ending up in between the pressure-holding part and the outer part of the cap (and thus also going through the little overflow tube that connects to the filler neck of the reservoir). This is repeatable (reappears if I clean everything and later check again).

Coolant gets used up while driving and I have to refill periodically (increasingly often). If I would let the coolant reservoir get empty and continue driving, the engine would overheat, but this has not happened since I have always topped up before that happened.

There is no dripping of any sort when the car is parked (no coolant, no oil).

When the coolant gets used up, the coolant reservoir gets filled with gas (air or combustion gases).

I cleaned both the throttle body and idle control part a few years ago after the throttle would stick slightly open, with increased idle speed as the result (it solved the problem).

The spark plug wires, ignition coils and spark plugs were replaced recently (my first attempt at fixing the misfires), with only original parts used.

The thermostat is present and was functioning properly for many years. The change in engine temp behavior has come slowly and gradually.

All codes:

PCM P0300 current. Engine Misfire Detected. Illuminates MIL unless there are only very few, isolated misfire events. Flashes MIL if misfires are occurring at a sufficiently high rate to risk damaging the catalytic converter. Disables TCC* if misfiring continues.

* My DeVille has a VCC rather than a regular TCC.

PCM P1381 history. Misfire Detected No ABS/PCM Serial Data. Could indicate false P0300.

PCM P1645 current. EVAP Solenoid Output Circuit. Illuminates MIL.

PZM B0533 history. Fuel Level Sensor Shorted to Battery.

RFA B2560 current. I cannot find a verified description, but it indicates that I should resynchronize my RKE fobs or change the RFA unit.

I have seen a lot more of P0300 than P1381, which also appeared much later. I can also feel and hear the misfires while driving. While idling, the misfires can be felt and heard as puffs through the tail pipes. The MIL is on, and it has been blinking occasionally when accelerating. The TCC (or VCC) is disengaged, which I can hear (engine revs faster for a given steady speed), feel and see on the tachometer. If I reset the codes while driving, the TCC engages for a while until misfiring is detected and it is disengaged again.

I do not think that a faulty EVAP should cause misfires, and P1645 started appearing long after P0300.

For some reason, the O2 sensor codes that I have seen are not set now (there have been several before, but unfortunately I do not remember the code numbers now).

I was about to replace the FPR and continue with other tune-up stuff just about the time when the oil in the coolant started appearing, but I did not want to continue with that when something much more serious was going on.

Abbreviations used:

ATF: Automatic Transmission Fluid

EBTCM: Electronic Brake and Traction Control Module

EVAP: Evaporative Emission

FPR: Fuel Pressure Regulator

MIL: Malfunction Indicator Lamp

PCM: Powertrain Control Module

PZM: Body Control Module – previously referred to as Platform Zone Module

RFA: Remote Function Actuator

RKE: Remote Keyless Entry

TCC: Torque Converter Clutch

VCC: Viscous Converter Clutch

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Much much better! Will review along with others


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Does the car misfire or misfire worse on a cold start.

My 96 misfired on a cool start (went away for a week, came back) in the summer, it had never done that before.

Slowly over the course of a year or so the misfire at cold startup became more of a daily occurance. Ran great after a few minutes.

Long story short headgasket blew. Must have been leaking coolant into 1 cylinder, then 2. Then it blew completely causing exhaust to force into the cooling system.

Reason why I mention this is because the symptoms I had did not quite point to head problem but I had the same issue as you. Slowly over time it occured til one day it blew completely and the problem was obvious. I had to top off the coolant about once a month but mysteriously it did not leak or smoke. It took about a gallon for every 2 months


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Yes, the misfire is often worse right after a cold start. Then it can feel like it runs on 7 cylinders for 10 seconds or so.

When idling warm, there is usually one or two misfires per second, (as felt and heard at the tailpipes).

I did connect an OBD II reader to the car over a year ago (maybe over two years, before the oil problem, when I only had the misfire and O2 sensor problems). It showed fuel trim values that were off a lot to the positive (more fuel, and uneven, i.e. large difference between left and right bank). But that has become secondary to the oil in coolant and loss of coolant situation.

With the OBD II reader, I could see that there were a lot more misfires on one cylinder (don't remember which now, maybe 5), even though I have not seen the cylinder-specific misfire codes (only the general P0300) on the on-board diagnostics.

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Based on your description of the symptoms, it appears that the headgasket(s) are in the early stages of failing. I think it is time to do a combustion test on the coolant to verify the integrity of the headgaskets.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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hjb981....You stated you have not done the combustion bypass test. I highly recommend you do that asap. However, if it is using coolant at a high rate it may be hard to get old coolant in long enough to get accurate test. When you add coolant without driving (I can't personally say how much driving is necessary) you can easily get false pass. For the price, and ease of doing the test, It should be one of the first things done to rule out head gaskets. If the head gaskets end up being the problem, you then make a decision on whether its worth your time and money to repair without, first spending countless hours and money trying to repair a miss, radiator or other things a person would repair if head gaskets were good. If it turns out to be head gaskets, you will no doubt have new wires and plugs, valves checked etc when it goes back together. I don't know what effect the coolant being in the exhaust could have on o2 readings, anyone here have an idea on that?

Your initial statement in post 23 is classic head gasket indicator. ( Yes, the misfire is often worse right after a cold start. Then it can feel like it runs on 7 cylinders for 10 seconds or so.)

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