head gasket or not head gasket, that is the question!

Lexluther · 12-22-2007, 04:52 PM

My car has 180 psi X 4... doesnt miss, but has a few signs of a head gasket failure..

1: when you start it cold, the exhaust smells of gas and antifreeze. until it runs for a minute or so then it clears up.

2: there seems to be too much pressure in the water overflow tank.

3: sometimes the temp is a little higher than normal.

the idle is a little rough. is there anything else it could be?.. or is the HG leaking?

Techno Duck · Techno Duck's Garage

Does the car misfire for a few seconds on cold starts?

My car at about 90k miles blew the headgasket. Car ran absoltuley perfect except on cold starts. Coolant was pooling into the cylinders when the engine was off and the cooling system still pressurized (and hot). Basically coolant was being pushed past the fire ring due to the cooling systems pressure. The engine would misfire for about 10-15 seconds before it all burned off and ran perfectly afterwards. The fire ring had split in two, this was due to decomposition of the fiber material around the fire ring. I did a compression test which did not turn anything up.

Most easy way to tell was to start the car, and if it was misfiring, immediately shut the car off. Then pull each spark plug out. One of them was wet and if you looked into the cylinder with a flash light, you could see coolant pooling ontop of the piston.

Lexluther · 12-22-2007, 05:37 PM

Thats exactly what it does, it starts up cold, sounds like its flooding to death, missing and stumbling, for about half a minute tops, and clears right up.. if you get out of the car and smell the exhaust it smells like gas and antifreeze(the sweet smell).. i thought it was fuel injectors leaking into the cylinders, but i pulled the rail and laid it on a piece of cardboard to see if they leaked and not a drop. will this effect mpg?... and maybe cause it to idle kinda rough?

Techno Duck · Techno Duck's Garage

I would start looking into replacing the headgasket in this case. Its only going to get worse with time. Mine drove fine for over 150 miles..but i was fearing hydro locking the engine. What you can do to prevent the misfire on start up, is after you shut the car off, very carefully open the expansion tank cap. Be very careful doing this because it can potentially depressurize very quickly and spray very hot coolant onto you. So put a rag or two over the cap. After its depressurized, tighten it up again.

Mind you this is a band aid fix. Its only a matter of time before you get the cloud of white smoke from the exhaust!

Lexluther · 12-22-2007, 05:50 PM

I will try that, it will help reinforce that the headgasket is in fact bad. is the head gasket a bad job?

Techno Duck · Techno Duck's Garage

Its not a bad job, just alot of stuff to take off. Consider replacing the timing and balance shaft belt as they are going to need to be taken off.

In a nut shell you need to remove..

-timing belt / balance shaft belt
-fuel rail
-intake manifold
-cam tower
-cylinder head

The exhaust manifold can be left on or it can be taken off. It depends which method you want to go with.

John_AZ · 12-23-2007, 05:02 AM

Use the 3 step head tightening torque system as per Clarks Garage. One other tip I found was to WAIT at least an hour or more between steps and gently tap head between steps to help miniscule misalignment and sticky spots. '84 944 head torque specs.
When the head is off and to a machine shop replace anything that looks bad, hoses, heater valve, ICV mounts and the list goes on and on and on...

Feliz Navidad

John_AZ
1988 924S + 1987 924S

Lexluther · 12-23-2007, 05:48 AM

Thanks, I am gonna take the radiator cap off this morning, release the pressure, start it for a few seconds, and recheck the cap pressure... tonight i will release the pressure and see if it helps the engine start better tommorrow. I guess i'll be buying a new head set.

Lexluther · 12-23-2007, 05:53 AM

Another quick question, will his cause my "running rich" problem, IE effect the engine vaccum?.. since i got the car, is has been getting poor gas mileage, and running somewhat rich, doesnt smoke... but could a head gasket, screw with the engines vaccum?

Just curious.

John_AZ · 12-23-2007, 06:26 AM

When you check the physical condition of the vacuum hoses and connectors you may find leaks. The hoses to the ICV-idle control valve, crack. The oxygen sensor may be causing your car to run rich. I cannot say what the correlation may be.
Sears and others sell a radiator pressure tool to assist you in checking if antifreeze/pressure is leaking. A leak down test is also a good idea. If you have a Harbor Freight nearby the leak down tool is on sale with coupon for about $30.

Happy holidays

John_AZ

Lexluther · 12-23-2007, 06:36 AM

I already checked the vavuum lines, replaced the O2.. with no improvement.. I was kinda hoping this all might be connected..

Razorback1980 · Razorback1980's Garage

I am not saying won't affect fuel mixture, but I'm not sure a small leak will cause that although pouring antifreeze on your O2 sensor isn't a good situation. I bet the problem will be fixed if you replace your head gasket as you will probably replace all the vacuum lines under the intake when you change the gasket.

Lexluther · 12-30-2007, 12:24 PM

Has anyone had any experience with that screw in the mass air meter? i have been reading it can adjust my CO, or air-fuel mixture.. can this fix my "rich" exhaust.? assuming I still have it once the head gasket replacement doesnt help. I have tried everything else except the DME.

Techno Duck · Techno Duck's Garage

Do not adjust the screw unless you have a wideband O2 sensor on the car or are having it dyno tuned.

Lexluther · 01-01-2008, 01:19 PM

I dont know what you just said, but i havent touched the screw, me next order of business is to replace the head gasket.. is this doesnt do anything for my "rich" problem, i'll move on from then.

bholmes · bholmes's Garage

Lex,
I don't spend much time on this site these days as I am trying my best to hate my porsche so I can stand to sell it after I fix it for hopefully the last time. However, sounds like you've got some pretty good advice on the head gasket, I have one layin around if you are needing one. It came with a gasket set I got, but I wanted to use a widefire gasket on mine as I was going to turbo the car. Either how, if you need just the headgasket and can get the intake gaskets seperate else where, I'd probobly cut you a pelicanite deal on the headgasket. As for the running rich....how long has this been a problem? When you have the manifold off for the head gasket be sure to change the idle control valve hose like John_AZ suggested. It's under the intake. This is a big spot to find vacuum leaks which will cause a rich condition. I had problems with this one as did speedy. Best bet is to just by a new hose and not try to cobble it like I did. I am pretty poor so I couldn't justify the hose. Also another pelicanite tracked their vacuum leak down to the o-rings in the ICV and had to change them. So don't forget to check those. Also if it's a condition it's had for a while and isn't a new trick for your car, you may check the FQS on the DME, it can lean or richen just a little bit and it might straighten it up. The you can buy a tool to adjust the fuel quality switch or just whittle one out of an old golf tee. However I doubt it's the FQS. Best of luck. Let me know about the head gasket.

nynor · 01-03-2008, 06:48 AM

the intake gaskets can be found separately, although there is nothing special about them and would be easy to make from gasket paper, IMO. also, if they don't get damaged during removal, i've heard of people reusing them after giving them a light coating of RTV. that said, new is best.

Lexluther · 01-04-2008, 03:15 PM

I havent been on in a few days, so i didnt read your post in time, i ordered a head set from pelican today, oh well..... i hope to tear it down tommorrow and try to get the head cleaned up and the surface checked ... are the valve seals something i can replace, with a valve c-clamp.?

The car has ran rich since i got it, i have checked all i can and there still doesnt seem to be improvement, but i am limited to what i can "reach' under the intake, but when i remove it from the head, i will try to replace hoses... and clean out the Idle Air Valve.. I think the head gasket has been bad since day one... so maybe it has something to do with it..

earlr85944 · 05:34 PM

yes you can replace the seals with the valve c-clamp

Btw- drain the antifreeze before pulling the head

USMC_944lover · USMC_944lover's Garage

Well, to get the bolts out in the cam you need a long 6mm hex key. most likely not a socket, might have to be just a hex key. I had the same problem, had to buy a 3 dollar tool. One thing to remember, it is VERY important not to drop the valve lifter when you pull the cam off. They are very expensive. And I just fixed the problem today as a matter of fact with a lifter not "pumping" back up. If you plan to take more than a couple days to do the job you need to soak the lifters in oil. I didnt do that and now I had to use alot of things to get it back up. Otherwise when you start your car you will hear this : http://www.youtube.com/watch?v=TiMmb5x1QTI

My video of my engine, scared this **** out of me! Thought I did it all wrong. you can read my post about "Help! Just got Head Gasket Done"