Fast overheating, not sure what to do

[Peter Green]

Hi all. I've read the forums before posting, couldn't find exactly what I have.


From the beginning:

1987 Porsche 944 with over 200k mi. Was running perfectly since I got it 2 years ago, I never changed anything significant.

The temp gauge was always at 1st mark steady. Now a week ago I suddenly saw the red "!" and the temp was over the 3rd. I stopped the car, waited for it to cool down, refilled with water, drove ok for a day, then realized it had lost
all the water again and overheated. I went through a few cycles of filling it up and loosing all the water until eventually found a hole in the hose going from the container (with the cap where you put the coolant in).
Fixed the hole and thought that it was over.

But unfortunately not.

No what else (maybe) you should know about the car:

A/C doesn't work (makes the noise but doesn't cool, maybe just out of freon, I never checked)
Heater doesn't work (blows air but no heat)
Power steering behaives weirdly when it rains. Sometimes I loose the power steering when turning and the wheel gets stiffer. Have no idea if matters.

Now, on to the symptoms.

The car overheats very fast, I bleed the system numerous times and still it acts the same - when I unscrew the high-point bolt it releases a ton of hot air. Then when the water starts running from it in a steady flow,
I re-fill the reservoir, and close the bolt.

I also tried watching what happens with car running with the radiator cap off: The car heats up, the water runs up and overflows (a lot) with bubbles, then stabilizes. It still goes up and down and is "boily" but it seems like it's pretty stable. Then I put the radiator cap on and it still overheats fast. Unscrew the bolt - ton of air comes out.

Important thing: If I let it overheat a little bit the water flows from underneath the car. I couldn't locate the source where it's coming from.

What are the steps for identifying the problem further?

Head gasket (analyzing the air for exhaust gas? there's no heavy white smoke coming out from the exhaust) /
Waterpump? (water coming out of it? - should I lift the car and look from the bottom?)
T-stat? (I don't know the symptoms for that)
Any other valve there is that could be failing when the car gets hot (so I see the water flowing out?)

Appreciate your help guys.

- Peter

[snake1996]

First thing you need to do. With engine cold fill with water, pressure test cooling system. Look very carefully for any leaks. If you find the leak repair that first. Second thing, Install new t-stat. Fill cooling system, carefully bleed all the air out of system following bleeding proceedure. Run the engine up, if all is ok you are good to go. If not, the next thing to do is a combustion chamber leak test. Hopefully your leak is not the water pump. If it is the water pump, do combustion leak test before wp is replaced. You possibly have a blown head gasket. Your power steering issue sounds like a loose or worn out belt. This is not a cause of overheat condition. Just to be clear. If you have to replace water pump, do not do that until you make sure there is no head gasket issues.

[gricec]

If water is flowing under the car when its running then you still have a leak. If its leaking that bad look under the car and you should see it dripping down somewhere.

[Peter Green]

thank you.

It only starts leaking when the cars gets severely overheated so I can't really spend too much time looking where it's leaking from. But I get the point, I'll find out.

[968rz]

Head Gasket.

[mikepellegrini]

+1 on the headgasket. If it only leaks when overheated it's probably just coming out the radiator overflow.

There are a few diagnostic things you can do. A compression test is top of the list. What you're looking for is a large difference between the cylinders.

Say where the compression is 135, 130, 140, 70. That'd indicate major problems in number 4.

The exhaust gas test for coolant is another. You can find those kits all over. With that, you fill a test tube with a reagent and then you put a cork with a tube leading off it into the radiator cap outlet, to pipe gas from the cooling system into the test tube so it bubbles in the reagent. If the reagent turns yellow, combustion gasses are present. Head Gasket or Combustion Leak Test Procedure (Gasoline Engines Only)

I think most auto parts stores would have a kit like this, as does Harbor Freight.

Also take a good look at both your oil and coolant to see if there's any contamination (where either looks like a "milkshake").

If all those tests are negative, then maybe look at your thermostat. You can diagnose that easy enough with an infrared thermometer (to see if it's opening).

But with the symptoms you have - all that excess air pressure - I'd put my money on the headgasket.

[KEV951]

have you checked out any REAL TEMPS with a temp gun?? Thats where you start...check temps at thermostat housing/ pump. check upper hose, check the head. your guage could be fooling you. The fact that your heater doesnt work may be a vacuume line. or broken heater valve. the car is suppposed to revert to heat only if the heater system has failed. check all the basics.

[Peter Green]

Originally Posted by KEV951

have you checked out any REAL TEMPS with a temp gun??

No really need to, It is obviously overheating and going so fast

mikepellegrini, KEV951

thank you, I will check everything

[Peter Green]

Checked the cylinders pressure:

77
78
90!
80

How come it's so low??.. should be around 170 right?

Should it tell me anything?..

No leaks found while pressure-testing the cooling system.

[Rasta Monsta]

Repeatedly run dry and overheated. . .look out Mr. HG.

HOWEVER, how old is the water pump? I guess it is conceivable that the stress of overheating caused the impellor to loosen from the shaft?

[Peter Green]

I never let it stay heated, always pulled right over and shut it down.. within 10-20 seconds i'd say..

[Peter Green]

Just went ahead and sold the car as is for $900. Thank you all for help. Really sorry to let it go but I need a working car right now

[gncosta99]

If water is flowing under the car when its running then you still have a leak.