Cooling Problem?

[fabrotz]

I am a first time poster and first want to say how much great information is shared on this board.

I just bought an '83 944 that appears to be all original mechanically. I live in Las Vegas and daytime temps the past week have been around 120F.

The car will idle all day with the AC on max and not pass the 2nd mark on the temp gauge. The fans appear to be working correctly turning off and on at the specified temps(by gauge marks). Driving the car gingerly and under 3000RPM temp stays under the 1/2 mark. If I drive aggressively or over 3000RPM the temp will climp past 3/4 and head for the red. AT this point the only way to cool it down is to turn off the AC and run the heater(try that at 120F!). Even then it will just stay below red and will not cool down further. Is anyone here driving in similar conditions?

I suspect the water pump may be on its way out or maybe a thermostat stuck half open, or maybe the radiator is clogged with 20 years of desert sand. I have not tried to bleed the system yet...does this sound like the symptoms of a system that needs bleeding.

Any ideas?

Thanks in advance for any and all replys.

[Lawrence Coppari]

You seem to be on the right track. I would try the bleeding first because it costs you nothing. On my '86 951, the bleed bolt is right on top of the block where the water exits to the radiator. Mine takes a 12mm wrench.

The thermostat is what I'd look at next. It is difficult to get out. It is located in the big lower opening of the water pump where the coolant enters. It is held in place by the infamous snap ring. If you can get it out, put it in a pot and heat the pot on the stove. Watch to see if the thermostat opens fully at the temperature it is supposed to.

I had a water pump go bad on my turbo. But it would pump ok at high rpms. My car would tend to get a little warm at low rpm like when I drove it up a mountain in 5th gear. In third it would do just fine. I changed both the water pump and thermostat. However, in my case, there thermostat was working properly. I never have had to deal with 120 F.

One last item. I have seen people make the mistake of putting 100% antifreeze in the engine. It will cause the engine to overheat when stressed.

[Porsche944]

Have the same exact symptoms with my '87.

I went through the "normal" route of replacing the thermostat, replacing the radiator cap, cleaning the radiator and A/C condenser fins, checking the fans, flushing and refilling the cooling system, but nothing worked.

At that point I bit the bullet and bought a head gasket kit and a water pump. I have the engine torn down, the head goes to a machine shop (Thank God for NASCAR shops!) and the water pump gets installed tomorrow.

I should have the head back in about three days so I'll let you know how it goes after the engine is back together.

BTW: Are your radiator hoses REAL firm? The reason I ask is that when the 84's head gasket was getting ready to fail (Which it finally did at a most inopportune time!), the radiator hoses were so "tight" I could barely squeeze them. After I replaced the head gasket the engine runs a lot cooler than before, and the upper hose is always "soft" and easy to squeeze.