coolant reservoir overflow (but engine temp reads low)
 

I left my '85 944 parked for a week, and then drove it about 5 miles (mostly on a small highway). I parked it for about two hours, and drove it back. The whole time, the temperature gauge never went above halfway (normal for this car). A few minutes after I parked the car from the return trip, I went out and noticed that the coolant was running out of the overflow tube on the expansion tank. (I'm fairly certain that it wasn't leaking on the way in; there was no trail leading into the parking space, and I would have stepped in it on the way to the house).

I figured that if the system had enough pressure to blow past the cap, that it wouldn't be a good idea to open the tank, so I just collected as much of the coolant and discarded it. However, I'm stumped as to how an air bubble could have formed in there while driving-- I'd expect that after adding more coolant without bleeding.

Ideas?

I trust the temperature gauge as being roughly accurate, because when I bled the system, the gauge rose normally from cold (I bled it later that evening) to past the middle, where the radiator fans turn on, and then it went back down.

Since then, the coolant level has been dropping slowly, but I can't seem to catch any dripping when I leave the car parked.

Chances are you have a loose hose somewhere - letting coolant lea. amd letting some air in.

Check all of your hoses/connections.

AFJuvat

I'm not seeing anything obvious, but there's a bunch of road grime towards the firewall that could be hiding a crack or leak.

Poking around in the overflow reservoir, I noticed two things: 1) there's a bit of oil in there. I swear I just had that fixed and flushed not too long ago, and 2) the cap is fairly easy to turn-- how much pressure does it have to hold for things to work right? I barely have to press down on it to get it to turn freely.

I don't know. I bought a truck that runs well so I wouldn't feel compelled to tinker with the 944 until after grad school, but the 944 seems to say "fix me" every time I walk by...

not to be too picky, but in your .sig, shouldn't it be "wie schnell man treibt"?

---

Der Horizont vieler Menschen ist ein Kreis mit Radius null.

Charles,
The rad cap shpuld be kinda hard to push down to turn,it should hold about 15lbs to function correctly, I would get a new one. What does all the sig. mean? I can't read German.

The horizon of many humans is a circle with radius zero.

"It's not how fast you drive, but how well you drive fast"

Hi,

Have you considered of blown head gasket?

Maachan

my computer at home is down, using my company's now.

How did you fix this...
 

Hi,

Keen to find out if the new radiator cap fixed this or was it a hose etc..

Thanks

Simon

Wish I could post something useful here, but the problem has not resurfaced.

I think the radiator cap is in working order, but I took a look at the reservoir opening, and the plastic seems to be worn. That would explain how easy it is to turn the cap, but it looks like it still holds pressure.

Now, I just drive with a jug of coolant and a gallon of water in the back seat.

Again, I really can't take much time to mess with the car until after grad school (which, unfortunately, is looking like a moving target these days).

If your cap does not hold 15 psi, there is a greater tendency to form vapor in your system, the reason being that the coolant has a lower boiling point when it is not under as much pressure. Cap should not be too easy to get off.

It could also be a leaking head gasket. Hopefully, it is just the cap.

I think it's the cap. Does your fan run on low speed after you park it?

It depends. Often, the time between getting off the highway and when I park is just enough for the blowers to cycle on and off once, so the blowers don't run after I cut the ignition.

If I leave it running while I check the mail, and then park it down closer to my door, it will usually warm up and keep the blower running for a little while after I turn it off.