No Thermostat - yet another mystery

3sonfather · 10-14-2001, 04:25 AM

I've been troubleshooting a mild overheat symptom - car gets to 3/4 before fans kick in. I replaced the radiator thermo-switch - none for better and verified that my fan circuit works (bridge thermo-switch wires). My next approach was to pull the thermostat from the housing, but to my surprise -- no thermostat present.
Two questions:
1. Could not having a thermostat present a hotter running engine? (thought: Perhaps not having the thermostat as a restrictor results in not having enough pressure to circulate coolant through engine channels).
2. I do intend to put a thermostat in. What is the orientation of gaskets or o-rings? (o-ring, then thermostat, then gasket, then snap-ring??)
Thanks All

Diesel · Diesel's Garage

This is very common. The previous owner was prbablty trying to cure an overheat problem by taking out the T-stat. When you do this, especially in a car with an overtaxed cooling system like the Porsche's, it heats up. The thermostat acts as a restrictor keeping the coolant in the radiator longer where it sheds more heat.

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Dan, '78 Pearl white 924

CrazySOB · 10-14-2001, 06:30 AM

3/4 is where the fans are suppose to kick in. You can get a lower temp. fan switch that kicks in at the 1/2 way mark.

Steve

drew1 · 10-14-2001, 08:02 AM

with the double valve thermostats, i wonder if the right ratio of coolant to different places (head, block) is messed up if you run without one.

drew1

3sonfather · 10-14-2001, 09:26 AM

I just think the schlep that owned the car before or the mechanic forgot to put one in when he supposedly replaced the water pump. I should have suspected this since when I did the timing belts I found that the t-belt idler pully was missing as well.
Oh, I've ordered a gasket, o-ring, and snap-ring along with the thermostat and I find that there is a thermostat spacer as well. I still need the sequence of installation with all of these items if anyone could respond.
Thanks,
Scott
84' 944

lm6y · 10-14-2001, 09:57 AM

Check your E-mail, I sent you the page from the factory microfiches.

3sonfather · 10-18-2001, 07:21 PM

After some research on google, I learned that the thermostat is necessary to channel water back through the jacket of the water pump and into critical areas of the engine (whew, my Porsche has nine lives). I am having one problem now:
NEED HELP! ** I can't get the bloody inner seal in installed behind the thermostat ** NEED HELP!
Did they do away with this seal on newer versions of the water pump. The seal is quite rigid and appears to be 1/8" oversize interference to the hole in the water pump.
Thanks,
Scott
84' 944

Ehab · 10-18-2001, 07:35 PM

When I replaced mine with the lower temp T-stat, there was no gasket and O-ring or spacer, there was just one gasket that fit around the perimiter of the T-stat before you install it, then you just place the thing in, and snap ring ... and voila ...

I also didn't have a T-stat in there at first, but that was to overcome an overheating problem due to the fact that one of the fans was burnt out, and the other was always on ...

When my mechanic changed it, he put in a commercial one at 92degrees, so the car was overheating regularly, but he fixed the fans. It wasn't until I got on this board that I figured out the problem and fixed it myself ... new fan, new T-stat, new T-switch, now it kicks on at 1/2, and off at 1/4 ...
good luck
E

3sonfather · 10-22-2001, 12:39 PM

Saga continues...
I put in the new thermostat (80 deg C) and now the motor gets borderline overtemp. This after a thorough burp of all air in the system. I can say that it is not a radiator / fan situation since it gets real hot during highway driving. I stopped driving the car and suspect I may have created a leak in the head gasket; a light fog during start-up now. I was speaking to ********** and they suggest a "thermal bypass plug" that they make and sell that goes in place of the thermostat and blocks off the flow of coolant to create the coolest engine conditions. I didn't jump on this just yet since I haven't heard of such a thing. What do you all think?
Thanks,
Scott

Scott R · Scott R's Garage

Why don't you think it's the radiator? I would overheat on the highway and run 1/2 around town. Turned out the rad was shot. Very poor volume of flow through the core. It was working, just not well enough to cool the motor. Got a new rad from Pelican and it ran around the 1/4 mark after that. On a side note the font of my rad was so covered with bugs and crap that it would never get air at any speed.

drew1 · 10-22-2001, 01:07 PM

3 son father,
The bypass plug instead of a thermostat sounds like the round track method of running a plate with holes drilled in it instead of a thermo stat.

drew1

3sonfather · 10-22-2001, 01:24 PM

Drew,
The way it was described to me was like an expansion plug and I believe it goes in at the base seal. They tell me it is very popular in Florida with all their hot weather. If I just knew how the coolant travels throught the water pump and about the system, I might feel comfortable about installing it. Someone here must know about it.