PeteL

Since returning from my Afghan vacation, have been driving the 944 more. On cold starts, it feels like it is running on 3 cylinders. Once warm (several miles into a trip) it runs smooth. Last night I pulled the plugs, three were pretty dark, one was clean. Number 4 appeared to be fouled. Cleaned the plugs, cap and rotor and replaced. Last night the car sounded and felt great after that, but perhaps it was slightly warm, as I ran the car before pulling the plugs and cleaning them, so maybe that's why it ran well....
If this turns out to be a head gasket, look for a Headgasket changing party in Tampa soon.
Anyone in Tampa know how to do a compression check, and more important, have a compression tester?

Charlotte944

Hey Pete!

Glad to hear you made it back in one piece!

Doing a compression check is easy and straight forward, but there are different techniques.

Some folks do "cold" and "warm" checks, others do "dry" and "wet" checks, and still others do a combination of the two.

Personally, I do a "cold/dry check" and if I don't like the numbers I do a "cold/wet" check.

The basic procedure is to remove the plugs and the DME relay. Install the compression gage and then use the starter to turn the engine over at least 4 revolutions. Record the pressure reading, release the pressure (release button on the fitting below the gage), and move to the next cylinder.

Readings should be fairly close cylinder to cylinder. If you have one or more cylinders that are reading low, try putting some engine oil in the cylinder and re-test. If the cylinder still reads low, install the plugs and DME relay and run the engine for a bit, and then re-test. Running the engine will cause the rings to expand and may give a better seal.

Additonally you may want to do a leak-down test. This is a little more involved and requires a leak-down gage and an air compressor. The basic theory is to pressurize the cylinder and then measure how fast and how much the pressure bleeds off.

With that said, I would keep a very close eye on your coolant level, gas mileage and engine temp.

If you have a leak in one cylinder (like I had on my '84), compustion gasses will pressurize the cooling system, making the coolant hoses VERY firm when the engine is up to temperature, and you may notice that the coolant level drops below the MIN mark on the expansion tank.

Additionally, coolant that enters the exhaust will cause the O2 sensor to fail prematurely, resulting in rich running and bad gas mileage.

Some other indicatiors are cleaner than normal plugs and pistons. With my '84, #3 plug and #3 piston top were significantly cleaner than the other plugs and pistons.

Finally, the last thing I noticed with my '84 was that under acceleration the in-dash temp gage would climb. I verified this by getting on a highway and crusing at the posted limit until the temp gage was stable. At that point I dropped into 4th and accelerated to about 75 mph. When I hit 5th gear I noticed the temp gage had "jumped" quite a bit, but as the car settled in at the higher speed the temp dropped back to "normal." A few weeks later the head gasket finally failed.

PeteL

Cliff
Thanks.
Gas mileage sucks.
Engine temp is fine.
Coolant level, I will need to watch.
The number three plug was clean, 4 was fouled, 1 and 2 were dirty.
After the compression check, and assuming it is the HG, how long would it take to do the head gasket?

tod84944

I doubt very much that your head gasket is leaking. You would be adding coolant on a regular schedule, and it would be overheating. Sounds like you a injector that is sticking open, or is gummed up some and pulsing slower than the others. This would cause that cylinder to run rich.
If you do have to replace the head gasket, after doing about 5, I have gotten it down to 1.5 hrs to take it apart, if none of the cam tower bolts don't strip!!! One trick to save a lot of time. Leave the exhaust manifold on the head. Just take the it loose at the down pipe. It is a lot easier to get those 6 bolts out than 8 nuts that are really hard to get at.

Charlotte944

Pete:

The one thing that makes this a "long" job is getting the head checked by a machine shop.

Beyond that, figure about 4 to 5 8hour days to drain coolant/oil, do the tear down, get the head to and from the machine shop, and then reassemble.

Speaking of machine shops, do some shopping around. I do business with a shop here that charges me a flat $168.00 to check a head and install new valve stem seals. Installing valve guides is an additional $20.00.

This is also a good time to replace belts, rollers, vacuum hoses, Oill filler seals, injector seals, and maybe do the water pump and front engine seals if needed.

Additionally this is the perfect time to reseal the cam tower (new seals are in the head gasket kit), replace valve quides (about $4.00 each) and replace valve stem seals (also in the head gasket kit.).

PeteL

I am encouraged by Tod84944 comments. I am going to proceed with the compression check.
It is the rough running at startup that has me most concerned. The car is running cool, which is encouraging, but it is also cool outside, not sure if that matters.
If I have to do the HG, then I will take the time to clean up the engine. Belts/roller/oil seals and waterpump are all recent (within 3 years). I will perhaps attempt to have some parts media blasted and powder coated. Either way, there will be a good HG party in the style of the Greaseslingers.

7thStranger

I think its pissed because you left it alone for 4 months.

If it makes you feel any better my S is still idling like crap after replacing the aux air valve, and an injector.

We definately need to have a maintance party before it starts getting hot.

PeteL

Do you have a compression tester? My garage is always available for maintenance parties.

hosrom_951

Sounds like what happened to my NA, but i had white smoke on cold startups (and the usual 3 cylinders firing instead of 4) and always low on coolent every other day..........

You seem to have a nice 'list' of 'while your in there' going on though

7thStranger

No, I don't have a comprssion checker.

But I do have beer and a couple of beach chairs.

PeteL

Think that will work?
But seriously, if this turns out to be the HG, would really appreciate any help.
I will supply the beer.

Charlotte944

That is because I've done three head gasket jobs. The first two were on NAs, and the third was on my turbo.

PeteL

Cliff
From what has been said, does it sound like the HG?

7thStranger

I wonder if you can get a compression tester from Autozones loan-a-tool service?

PeteL

Good suggestion. Will look into that.