Coolant Leak help!

[Its_Scott]

Hey guys! I was driving my 951 today and all of sudden I realize my temp gauge's red light comes up. I go outside of the car to take a look and realize that my car's coolant is pouring out. Luckily I found out when I was in my subdivision so I quickly drive it back home. I open up the hood and I see that the coolant has expanded and I'm guessing it overflowed out the expansion tank hose. So what could have caused this to happen and what can I do to remedy this situation? Is there any damage that could have happened to my car that needs to be addressed/checked as well? I immediately went home after I saw the problem so I wasn't on "hot" for a long period of time. I don't want to start up my car unless I know it is safe to again. Thanks!

[mattdavis11]

If indeed it was coming out of the expansion tank, then the thermostat could be a likely culprit. Put the nose of the car on an incline, open the bleed screw and fill it up with water until it drips from the bleed screw. Tighten it down, start it up and keep a close watch on where the water is escaping, the temp gauge, the fans, etc...

Report back.

[Its_Scott]

Thanks for the response matt. The coolant is indeed coming from the expansion tank. I saw the coolant overflowing exceeding the "max" line on the expansion tank. So I am guessing that the thermostat is the problem. I was looking up the thermostat and I found out that there is another thermostat for the turbo. Which one should I replace or is it both? Thanks!

[Techno Duck]

Check the condition of the expansion tank cap. If that cap cannot hold the pressure in the system, it will cause coolant to purge from the overflow tube because the fluid in the system is essentially boiling. The springs get weak and the rubber gasket deteriorates.

Next up is to check and see if the fans are coming on. Check both the fan relay and fan switch.

http://www.clarks-garage.com/shop-manual/cool-01.htm#latefanoperation

Easier to start with the simple stuff.

If both check out, your problem is probably the thermostat. You only need to replace the larger one found in the waterpump. You will need a good pair of 45* snap ring pliers for this job.

[Its_Scott]

Thanks John. How can I tell if the expansion tank cap needs to be replaced? The cap looks normal to me? What signs should I look for. Thanks in advance!

[Techno Duck]

Some autostores and shops can pressure test the cap for you. Usually you can just look at the rubber gasket and see how it looks.. when they get old the rubber cracks and splits open. The other failure is of the spring on the underside which compresses the rubber gasket against the mouth of the expansion tank. The caps are pretty cheap and you can usually find a universal one for less than $15 locally. If the cap looks fine, i would start looking into making sure the fans are turning on. If they are turning on and the car is still running hot, feel the lower radiator hose.. if its reasonably cool to the touch then the thermostat is not opening.