More Cooling Issues -- Help!

[TazioNYC]

A while back, my '87 951 was overheating -- going into the red and only revving the engine would bring it down. Went and had it checked out after a bit, and it ended up that the fan switch had stopped working, and there was a ton of air in the cooling system and very little coolant. So the techs filled it up with tons of coolant, we tried it out and the temps held fine and it seemed like I had thankfuly avoided something worse like a head gasket.

So I went on a trip, and after several hours of hard driving pull into get some gas. I pop the hood and there's no coolant in the tank, and so I stupidly get ready to add some more. My friend twists the cap off too fast before I can tell him otherwise, and boom, lots of coolant spills out. So wait until the car is cold after we get where we're going, put in some coolant, and the car runs fine throughout. Temps sometimes creep up into the higher field, bu never above the red and the fan works fine.

This morning, I checked the tank when the car was cold and there wasn't much in there. So I added a lot, up the the max line, went out for a few errands in the neighboring town, came back to where it was parked after a few hours (the car was "warm" at this point) and took a look and it was down around "min," which squared with the manual, which says it should be at max when cold and min when warm. So drive the 20 mins back, park the car, check in two hours ("warm") and the coolant isn't at the min level. There's still coolant in the tank, it's just not hitting the face of it to give a reading. Some questions:

1) Where has all of this coolant gone? I've been looking around, hoping it's not a head gasket, and just that I stupidly let a ton of air into the system and it just needs to be bled again.

2) What are the normal readings on the tank when the car is hot, warm, and cold?

3) Under what circumstances do others' 944 temp gagues creep up past half way and to the top? Is it typically pegged at normal for most folks no matter what? Mine tends to creep up during sloow "in between" driving, 20-40 mph in and around towns in minor traffic.

Any answers of advice would be greatly appreciated. I'm trying to talk myself down from thje ledge...

[blown 944]

OK you ALWAYS have to pull the littel bolt from the upper radiator hose when filling these things and bleed the system. They are VERY finiky when it comes to this.

AS far as cooland dissapearing I would do these things in order to make sure of whats going on

1) change cap to nice high pressure unit

2) look for any small leak at various areas of teh engine especially around the front byt the water pump or back behind the intake manifold. The hsoes on these cars get littel pinholes when they get older and can leak small amounts that are hard to see.

3) to rule out the headgasket I would
3a) pull the spark plugs
3b) use a compression gauge hose that screws into the spark plug hole and put a air fitting on the other end (some copression testers already have this)
3c) remove the reservior cap
3d) put the air hose on the end and go through the fireing order(start with cylinder one at tdc then rotate 90 degrees for the following cylinders) using about 120 psi at the compressor. You can also check for cracked cylinder wall using this method at BDC (highly unlikely).

you shopuld see the coolant rise and overflow out of the reservior if a cylinder is leaking by the head gasket.

I don't think you have a leaky h gasket as it generally will overheat very quickly and not come down even at cruise speeds.

[TazioNYC]

One more additional bit of info -- just did a few hard accel first gear runs down the street. My helpful onlooker said that about 20 ft after hard accelleration, there were a few tiny puffs of white smoke, but nothing major. I.E. nothing noticable unless you were looking for it.

So you think a solid bleed and refill could cure this?

[blown 944]

It is probably a small leak in your head gasket if it showing any white smoke on acceleration . Unless it is leaking onto the exhaust.

I would go through the proceedure above and be prepared to put a new one on it. Or at least rule it out.

[TazioNYC]

Wow, that's disapponting, I was fearing that. The temps did rise and the fan came on after basically having it sit at idle for 5 mins and then run hard up and down the street twice. That seems a little odd to me, but as already has been established, I'm no expert.

[geoffbaltz]

Sounds like the beginnings of a head gasket going bad. Probably a small pin hole and I bet it is at the cylinder closest to the firewall. My '86 951 had these same symptoms and I finally decided to pull the head and check it out. I installed a wide fire gasket and raceware headstuds and ran 18 psi of boost for 2 years before selling the car with no issues after doing the job. It took me a weekend to do.

Also, as someone else stated, make sure you do a proper bleed of the system when refilling after you finish the job. It makes for a solid cooling system.

-g

[TazioNYC]

Would this cause the engine to begin to eat oil?

[blown 944]

If it gets hot yes the rings and valves allow more oil by when it is excessively hot the oil also thins out alot. I would through the head gasket on and see what happens then. It is not very hard to do and not very expensive.

[TazioNYC]

For all those who guessed, it was a failing head gasket. Being repaired this week....luckily seems like no permanent engine damage.