1972 oil filter housing question

[swade]

Is there an secondary thermostat in the 1972 oil filter housing that passes oil to the front mounted cooler? It looks to me like there is only a pressure relief plunger in the circuit there. Does the pressure relief act as a thermostat by dumping very high pressures (cold oil) back to the tank and lower pressure oil (warm) through the front mounted cooler? Just trying to understand why the oil would head forward through a more restrictive path than just dump into the tank.

Thank you,

W

[Grady Clay]

Wade,

Your (non-front-cooler) oil filter console only has a pressure relief valve but it has a cover over the provision for a thermostat.
If you want to install a front cooler, you can fit a thermostat to your housing.
The plug in the casting must be replaced with a fitting (similar to the other two).
The additional thermostat is the same part as the thermostat on the engine.

The pipes and hose assemblies are unique to ‘72S-only.
Elephant Racing has very high quality aftermarket replacements.

This is a worthwhile upgrade.
The front cooler was standard on the ’72 911S, all cars equipped with Sportomatic transmission and as an option.

There is a lot of ’72-only oil system info archived here. Use Search.

Best,
Grady

[swade]

Grady,

My car does have a front mounted oil cooler that the PO installed. I am not sure that the console has the thermostat however. I will dig deeper tomorrow and report back. Thanks again for your help.

W

[dtw]

Your console almost certainly does not have a thermostat; rather, it will have a 'dumb' cover over a partially-finished bore in the housing, where a thermostat would go if the car had a remote cooler. If you install a remote cooler system, a machine shop can finish the bore at minimal cost. Then you put in a thermostat just like the one mounted in the engine case.

[Grady Clay]

Wade,

This may be an all-to-common problem – someone installs a front cooler without a safety pressure relief valve before the pipe to the front.

With the Factory configuration, the pressure relief valve in the oil filter console is prior to the front cooler.
If someone adds a front cooler by diverting the oil flow from the engine to the cooler and returns to the console, there is no safety.

Under normal operation there usually isn’t a problem.
If the car is parked hot, sits for several days and started when very cold (say, below freezing), the cold oil is pumped to the cooler first.
It is 100% oil on startup, not the 40/60% air/oil as in normal operation.
This situation can overpressure the cooler and failure result.

Let’s see how your 911 is plumbed.

There have been others on Pelican who have addressed this situation.

Best,
Grady

[swade]

I removed the console today and disassembled it to see what was inside. Fortunately the PO had done it right and the housing had been machined and there was a thermostat inside. I tested the thermostat in hot water and it started opening at about 185 and was full open by 200 degrees F.

Closed


Opening


Regards,

W

[swade]

And, had I bothered to search prior to sending the question I would not only have found the answer, but would have found the thread where the PO had documented it... my bad.

W