Head Gasket??

MadisonT · 04-18-2009, 08:18 PM

So I am looking for some help diagnosing one of my cars larger issues... I have a 1986 944 N/A

A large list of symptoms pointing to a busted head gasket such as smoke in the exhaust on cold days, water in the tailpipe, and losing coolant due to excess pressure in the reservoir (if the reservoir is at full and I go for a long drive it expels quite a bit...)

but also a lack of some of the ones I have read about; no coolant in my oil and no oil in my coolant as well as no issues with overheating. I also checked the spark plugs after letting the car sit for a while and firing it up and they don't look "steam cleaned."

I ran a compression test and all of my cylinders ran similar numbers (within the 10%) but I have no clue what values I should be looking for. My test values were 140-145-140-150psi

Any ideas?

Arizona_928 · 04-18-2009, 09:08 PM

what color is the smoke?

John_AZ · 04-19-2009, 07:03 AM

A leak test would give your the best indication. You said you have pressure in the coolant reservoir. This is THE indication your HG is bad. The leak sown test will show bubbles in the tank and you can pinpoint the cyl. I had the very same compression numbers. My HG was bad.

Very easy job! Do a lot of additional stuff. Replace the AOS seals, vac lines, any hose under the intake manifold, the heater control valve, new belt, new cam bolt, clean the idle control valve-ICV, check the "J" boot for cracks, replace the ICV rubber mounts, change your coolant. Before you start use a little SeaFoam to clean the engie and lifters. Then change the filter and oil. Take your time in removing the old gaskets. No scratches in the soft block. Clean the coolant gallys between the cyl. Do not remove the carbon on top of the cyl wall. Check your cylinders for scratches that catch you fingernail. If not bad just ignore. MORE...

How is that for a runon paragraph?

GL
John_AZ
1988 924S + 1987 924S

CJFusco · CJFusco's Garage

Water in the tailpipe is likely just condensation. Any coolant would get burned off in the engine.

Are you having any running issues? In other words, is the car stumbling at idle? Usually a minor head gasket leak will see the car running relatively well at-speed but then stumbling and sometimes cutting out at idle.

If your car is running fine, but you are expelling coolant from the overflow hose, I would guess you have a different issue than a head gasket.

MadisonT · 04-19-2009, 09:46 AM

Quote:

Originally Posted by AZ_porschekid

what color is the smoke?

white, also I'm unsure of what burning coolant smells like but my exhaust does smell a little funny...maybe "sweet" maybe not

Quote:

Originally Posted by CJFusco

Are you having any running issues? In other words, is the car stumbling at idle? Usually a minor head gasket leak will see the car running relatively well at-speed but then stumbling and sometimes cutting out at idle.

Some minor running issues. I wouldn't say its stumbling at idle as the rpm are fairly constant if a bit low and this is only on initial start-up, after I drive for even a minute or so it clears up. It definitely sounds like its having a little trouble on start up though, especially if i leave it for more than a couple days. Also the gas usage gauge (if it can be trusted at all) shoots through the roof for the first couple min after starting.

To be honest I would have jumped on the head gasket already with these symptoms but the records on the car show that the previous owner did all of the gaskets maybe under 20000kms ago and had the job inspected. Maybe he missed some of those scratches that John_AZ was talking about and the gasket has been deteriorating this whole time?

John_AZ · 04-20-2009, 02:08 PM

MadisonT,
To elaborate on the "scratches". Some gorilla mechanics try to scrap the remnants of the gasket material off with steel putty knives or machetes. The aluminum block is soft and will scratch easily. I spent more than 3 hours cleaning the surfaces with acetone, razor blades, scotch bright pads and bloody fingers.

But I digress, even if the PO had the HG changed, if he did not follow the 3 step torque method for the head, and waited the standard 45 minutes between the steps and gently taped the head to help set the HG between steps and say a voodoo chant....the HG may be at fault.

If your car stumbles at startup the coolant may be pooling in one cly and fouling your plug.

GL
John_AZ

Slam · 04-21-2009, 10:21 AM

I'd guess the HG. If the car is pressurizing the header tank, even after a good bleeding, then the HG is letting go.

earlr85944 · 04-21-2009, 01:25 PM

do the HG and use new nuts for the head

MadisonT · 05-10-2009, 05:31 PM

UPDATE:

Finally got the head off and the gasket is in perfect condition... Looks like it is brand new!

Time to troubleshoot a little. I have no clue where to look after the head gasket for a solution to a pressure in coolant problem. Any ideas?

Here are some pictures:

Razorback1980 · Razorback1980's Garage

Can you see anything on the spark plugs or headers that indicate coolant was in that area? The headers especially should show you which cylinder. The only places coolant can get compression would be in the top of the cylinder area. That would mean the cylinder could be cracked or the head could be cracked or the head gasket...not many other possibilities I can think of. The head gasket may not have sealed for some reason but it sure looks to be in good shape. Maybe locating the cylinder where the problem was will help you know where to look for other clues.

Techno Duck · Techno Duck's Garage

The headgasket was clearly replaced at some point as the gasket says 'turbo' on it. All of the gaskets now days have that. (not to mention that gasket looks basically new).

Double check the each of the fire rings around the cylinders and look for any splits in them.

Also bring the cylinder head to a machine shop to check the surface is perfectly flat. And of course check each of the cylinder walls for cracks.

John_AZ · 05-10-2009, 07:40 PM

First picture, far left, left side of left sealing ring on head gasket has half circle of brown discoloration. That is the side that sits on top of the block.

Second picture left side left cyl top--it appears the sealing ring was not torqued completely. Again, about half of the head gasket seal for the left cyl does not have an imprint of the head gasket. I increased the magnification of the picture to 200%. Just a guess. The shop may not have done the 3 step torque and wait 45 minutes inbetween and tapping the head gently at each step to seal correctly.

John_AZ

MadisonT · 05-10-2009, 08:03 PM

Thanks for the insight from everyone. A few things:

-Yes the PO did the head gasket not too long before I bought it.

-If the head was not torqued correctly or if the head was not machined properly wouldn't the combustion from the cylinder have deteriorated it some?

-The discoloration is most likely oil. I took the picture before really cleaning it off. I'll double check.

Aside from checking the cylinders/head for any cracks, is there anything else I should check to make sure I'm not taking this thing apart again soon?

John_AZ · 04:52 AM

Quote:

Originally Posted by MadisonT

Aside from checking the cylinders/head for any cracks, is there anything else I should check to make sure I'm not taking this thing apart again soon?

Here is my list:
You will never have a better time to reset the reference sensors than you have now. I would gently remove both sensors from the bracket, clean the sensors and the bracket holes carefully, and reset per Clarks garage.
PUT A RAG OVER THE TIMING MARK HOLE!! or you will drop a washer in your clutch.
If the sensors will not come out-just reset the gap.

Replace the AOS seals-(oil fill tube)

Get new rubber mounts for the ICV
Clean the ICV inside-carfully

Get new heater control valve

Replace the Vac hoses and connectors

Send out or rebuild injectors DIY-see tech section top of page

Hoses to ICV crack

Replace the "J" intake boot. The underneath rubber rots

Check all hoses under manifold and replace pinch clamps with quality screw clamps

Get a new cam Bolt-$3.50 at Pelican.

New belts

Clean out the galleys between the cyl and block. The rear bottom collects gunk in the corners.

Replace the OPRV coolers seals-You have lots of room now. Buy from Pelican by the piece-cheaper than kit price.

Reorder numerous times from Pelican

EDIT--Clean grounds at top of bell housing--there are 2. One for the negative cable and another tiny close by for electronics.

GL
John_AZ

krystar · 05-11-2009, 07:22 AM

valve seals! and do your timing belt and water pump if they weren't done very recently

thekidd · 05-11-2009, 11:05 AM

Is the fluid in the tail pipe water or does it smell like gas? I am going through a no start issue. It started when I put in new Ref. sensors, then didnt a few days later. Put in new pressure regulator and damper, started for a few days, then wont start any more. After I put in the regulator and damper, I had some white smoke, and "water" coming from the tail pipe. The tail pipe smelled like gas. Tested my AFM, and the "air sensor" I think it was called, didn't have resistance. Think the car is getting too much gas due too little air getting to the engine, IDK? I think the compression numbers look good, but check the AFM- Clarks.

Slam · 05-11-2009, 11:48 AM

Head looks suspiciously clean around #4.

I agree with all the WYIT guys.

TeenerTim · 05-11-2009, 12:22 PM

Did you do the compression check when the engine was hot or cold? A cold check would be more likely to show a problem. Did the smoking clear up after the engine warmed?

A "sweet" smell from the exhaust is usually coolant.

I agree that the #4 on the head looks too clean.

MadisonT · 05-11-2009, 01:43 PM

Thanks for the comprehensive list John_AZ

@thekidd: Thanks for the insight, I will check the AFM as per clarks, although I am positive that the fluid in the tailpipe was water. For quite a while I was debating whether the tailpipe smelt like the car was running rich (as you described) or smelt like coolant, but I believe it to be the later, especially after getting excess pressure in the coolant system

Quote:

Originally Posted by Slam

Head looks suspiciously clean around #4.

Some of that was me testing how easily some of the gunk came off. A simple fingernail/ rag test on various deposits.

@TeenerTim: Compression test was after the engine was warm. I thought that was standard for a compression test? And yes the smoking cleared up after the car had been driven for a couple minutes. The smoke would also last longer dependent on how long I let her sit between drives.

Thanks to everyone for all of the advice but I am still curious as to why the HG is still in such good condition. Even if the head was torqued incorrectly, or if the head was not machined properly, wouldn't the small gap be a cause for deterioration of the HG? Or could it have lived through being exposed to that combustion?

I am simply wondering how worried I should be that the head or cylinder walls are cracked (although my once over checks haven't shown anything).

Slam · 05-11-2009, 01:53 PM

If the car overheated and the head warped slightly, that would explain a lot. That plus an incorrect torquing of the head nuts on HG reinstall would be enough to cause the trouble you're having. When I got my HG out it looked pretty good as well, but I found I really couldn't tell just by looking at it. Sometimes wear beyond tolerance is invisible to the naked eye. It would be interesting to know if the head's flat. A good machine shop would be able to find cracks, if there are any. Has anyone here actually had a cracked head?

Have fun putting it back together. Mine turned into a relaxing few days' work and I'm glad I did it.