lineman82

Hey guys,

I have an '86 944 and I just got home and when I was stepping out of the car I heard some type of liquid pouring onto the ground. I got down and saw it was my coolant! I got under the car and checked and it was coming from the pressure release tube coming from my coolant tank cap.

What would be causing the coolant to be coming out of there?

hp18racer

Blown head gasket pressurizing the block. Thermostat or fan failure causing the car to over heat.

Mike C.

Yes sir.. a steaming bowl of not good.

Mark944na86

If you're really lucky, it might just mean you need a new cap.

lineman82

Okay I just got three different diagnosements haha

Does this mean anything? When I am driving it, the temperature will shoot up when I am at a stop sign or sitting at a red light but will immediately go down once I take off and start driving. Does that mean that it is my water pump that is going since it is belt driven?

roman944

too much coolant, or you are overheating

my car did exactly what yours is doing right now

I'd suggest that you double check and make sure that your fans are actually running - on my car they were disconnected

and I think they might have been disconnected because the P/O didn't want to deal with replacing the fan switch for some reason ... because when I got a new fan relay it didn't change things

another thing I did was check the coolant tank cap - its a cheap part to replace, mine had bad rubber thingie (I think) so it wasn't sealing right

my tank also had hairline cracks in it, and on closer inspection I found a bad hose right at one of the clamps (it was on the driver's side, big radiator hose @ the radiator)

lineman82

The fans are running, that is not the problem right now.

I just took the car for a five mile drive. It was fine on the way there and when I parked and got out it dumped more coolant. I waited about an hour, got back in and on the way home the temp. guage immediately went in the red. When I hparked it at home though it didn't lose any coolant.

Once it cools off I will go out and check the cap but do you think it could be anything else?

roman944

my car got hot enough to actually dump coolant only once, when I opened the hood - the coolant was coming from under the cap and from the "dump" line - also while that hose was "bad" it wasn't actually leaking coolant (yet)

are you sure your fans are working properly?

you can check out Clark's Garage for Cooling System, and start eliminating things - that's how I was working on mine

Mike C.

There are certainly other possibilities besides a water pump. The best way to diagnose is with a cooling system pressure tester. You can usually rent one at Autozone and the like. It allows you to pressurize the cooling system via the coolant tank (screws on to where the cap is) while the engine is cold so you can really get in close an look around. If you've lost a lot of coolant you may want to add some water and bleed system before doing the test (see Clark's about bleeding system).

lineman82

Alright I will for sure look in to that.

Could it possibly be the thermostat breaking? Cause that would cause the temp. to go up at stoplights and down when I move and get the rpm's up right?

And by the way, thanks for all the help so far guys

drift a 944

Another possibility which I don't think has been mentioned yet although I didn't read through quite thoroughly, is that a coolant passage could be blocked somewhere causing pressure to build up. In my car's case it was a severely clogged radiator, at one point.

Renting a pressure tester is possibly the best idea yet. It will indicate any leaks, whether it be external or internal. Remember to bleed the cooling system properly before testing or driving the car to ensure all air bubbles have escaped the system.

drift a 944

Ok, I just reread this, along with your follow up reply. Here is what I would test first...

Fill the coolant with water, bleed the air out, pressure test the system look for leaks.

If you find a leak, then you know where your problem is obviously... but what's happening is that when you are low on coolant, the car will stay in an acceptable temperature range while driving because its being cooled sufficiently from cool air going through the radiator.
When you come to a stop light, your minimal amount of coolant (which is flowing at a slow idle speed and has no cold air through the radiator) heats up very quickly and may start to boil, causing the temp gauge to shoot up to dangerous levels.

Now, with the thermostat in normal operation, when the car gets up to 'operating temp' it will open up to let the coolant start to flow through. If the thermostat gets stuck closed, the temp will continue to rise until the car overheats completely. I believe the temp in your car would not be going back down during cruising speed if the thermostat was stuck closed, I think it would continue to rise, but I could be wrong.

The only other thing I'm not too sure of myself is what happens when you use a pressure tester on a cooling system which has a stuck thermostat. I assume nothing because the thermostat is closed anyway while cold.

lineman82

Alright so from everything you guys have told me so far I will be going to advance around 2 today and renting a pressure tester and testing the car for any problems.

I will update this with the results from that later today and see what everyone thinks. If there aren't any leaks would it be the thermostat?

drift a 944

if you don't see any leaks, then it could possibly be any of these things (in order of easiest fix to worst):

cap, thermostat, water pump, clogged coolant passage, headgasket

if the pressure tester holds pressure well, and the car runs smooth, you could probably rule out the headgasket.

roman944

good luck dude, really hope its something minor (like a cap or a thermsotat)