Oil Thermostat/Front Cooler

Ok, I think it's time to replace the thermostat in the rear fender. While the car never gets really hot, the oil lines up front never get warm. The lines to the front cooler are in the right hand (sitting in it) side front wheel well? Also, is there a fan for the front cooler and where/how does it come on? Oh, we're workin on a 87 911. I'm thinkin it must be the thermostat but want to know what else if anything to look for. Also, I've seen whole thermos for sale as well as just the inside. Are they rebuilable? Thanks for any help.
rj

Get ready for some major "get greasy and dirty" work! I have an extra thermo valve that I have worked on (when I had nothing else to do that is) for years and have never gotten the old fittings loose!

I had a salvaged car and I would not let the valve nor the front oil cooler go when I move back stateside, and I could not get the old oil line fittings loose. Finally took a saw and cut the tubes as they were already bent from an accident and not useable again.

I was recently in contact with Warren on this and the one thing he suggested that I have not done is to use a propane torch to heat up the fittings to try to get them to budge. I will try this next and see how it works. Its real low priority (just spare parts for my car) and I tinker with it when time permits.

You probably will not get the unit off using normal crescent wrenches... I have some large metric wrenches and even they are not budging the critter. A metric "flare nut" type of wrench would be the best bet but in the 27 or 31 (or whateve the size is) will not be at every store nor cheap. If the torch and a little heat does not help I will get the dremel tool out and saw partially through the nuts and go from there.

No idea if you can overhaul the thing, but I assume that it is possible. Yours may be full of sludge or the springs or piston siezed. If the springs were broken and the innards still moving, then I would think that you should have oil flowing to the cooler all the time so I would assume that the parts inside the valve are either seized or sludged up so that they will not move anymore.

Good luck and let us know how it goes! These things are not cheap so its worth looking at overhauling them.

The unit by the pass rear quarter is a pressure relief valve not a thermostat.

You have only one thermostat which is located on the motor for both the oil cooler on the motor as well as the front fender hoop or cooler

Its possible the pressure relief valve is stuck closed.

The unit in the right rear fender is called a thermostat - the part is the same from 74-89 - it does incorporate an overpressure bypass circuit but the main function is to inhibit the flow of oil to the front oil cooler until the engine is at operating temp so as to not to blow the oil cooler. I don't know the temp that it opens at but Automotion has an aftermarket unit that opens at 170 F I assume the stock unit is similar.
There is a second thermostat mounted in the top of the iol cooler which closes at 244 F to turn on the oil cooler fan.
The wrench required is 36mm - Automotion sells a 12 point flare nut type wrench for about $53. If anyone knows of another source Id like to know as I'm in the market
for one. I checked the Snap-On catalog -they don't make flare nut wrenches that big.

Charlie '87 Carrera

According to the factory manuals I have they call it a pressure relief valve, in a schematic drawing of this I see no sensor in the unit for temperature, only a spring and a relief valve plunger
This unit is designed to reroute oil flow if your front cooler or oil lines are clogged

Oil Line Wrenches
I saw them in the TWEEKS.COM mag. under tools if there not avil. from Pelican. Cost 66.95

Mike Miller
89 911

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The stock thermostat opens at 215 degrees F. If you aren't reaching that, then your oil is staying in your motor and there's nothing wrong with your car. If you are above that and you can't hear oil flowing up near the cooler in the right front fenderwell (great way to check without getting dirty), your thermostat is not opening.
Your oil cooler has a "thermoswitch" that turns your fan on at around 250 degrees which should rarely turn on unless you are sitting in traffic with your AC on with 100 plus temps outside. You should never see those temps under normal driving with any airflow going through the cooler at all. It's really just a safety fan only.
Make sure you know that before your go through all that labor to replace something that's not broken.
Hope that helps.....

Ok, thanks for the help. Like I said I have never been able to get the car really hot so I'm not too worried about the fan thing. I just replaced the gasket in the thermo in the block so I knew that was there. The hottest I have ever got the car right in the middle of the gauge, hot day stand still traffic. It normally runs a hair above the first white mark. I'm thankful my car stays cool but I'm getting stationed back in Florida and I have a feeling if the front cooler is inop I'll know it pretty soon. I still have yet to get any oil up front