Thermostat Opening

[EPorsche]

At what temperature does the non engine oil thermostat open? I have an aftermarket 180 degree mocal one. Thinking about going to a 203 degree one.

[86 911 Targa]

Originally Posted by EPorsche

At what temperature does the non engine oil thermostat open? I have an aftermarket 180 degree mocal one. Thinking about going to a 203 degree one.

Why?

[juanbenae]

trump voter perhaps?

[Bill Verburg]

Originally Posted by EPorsche

At what temperature does the non engine oil thermostat open? I have an aftermarket 180 degree mocal one. Thinking about going to a 203 degree one.

Both t-stats open at the same temp, the melting point of the paraffin working medium in them

182-189°F
83-87°C

[EPorsche]

Right now my car oil temp is 170-180 deg winter or summer. At that temp its hard for water to boil off. What do you think Bill?

[MBruns]

I remember the engine cooler tstat opening at 180 deg. And the front cooler at 210 deg
Doesn’t make sense for both to be 180
Mike Bruns

[boyt911sc]

Originally Posted by MBruns

I remember the engine cooler tstat opening at 180 deg. And the front cooler at 210 deg
Doesn’t make sense for both to be 180
Mike Bruns

Mike,

Sorry. I hate to disagree with you. But I have done a lot of testing and investigation about this subject. Both the engine and auxiliary thermostats operate at similar temperature. At 185°F, the slide valve starts to open and fully opened by 200°F.



Test the thermostats side by side in an oil or weather bath and you will observe their identical thermal behavior.

Tony

[MBruns]

That’s good enough for me Tony, I see you have a lot of subjects to test !
Mike Bruns

[ossiblue]

Given Tony's experience and testing of these thermostats, my first suggestion to the OP is to test his Mocal thermostat and verify the temperatures it begins to open and, eventually, fully open. If it does not fall within the range that Tony and Bill have found to be correct--~185* through ~200*--then he should not use it. If the Mocal does, in fact, open at 180*, then it would be opening before the on-engine thermostat, effectively overriding its function. This would be consistent with the low oil temps the OP records.

IMO, testing of the Mocal is in order.

[Bill Verburg]

Originally Posted by MBruns

I remember the engine cooler tstat opening at 180 deg. And the front cooler at 210 deg
Doesn’t make sense for both to be 180
Mike Bruns

Sure it does, they both are the same design using the same components. The working medium is a paraffin wax that has a fixed melting point which starts the t-stat opening process.

The engine one opens first(at a lower oil temp) because it see's the hotter oil first.


the temp rise curve has a small plateau between the engine t-stat opening and the wheel well opening,

The oil temp rise curve looks like this

[MBruns]

Great info guys Thanks
Mike Bruns

[stownsen914]

To the comment from the OP about needing to boil water off, a couple comments.

The "spent" oil in your engine crankcase will be substantially hotter than what your gauge says. After the oil has done its work in the bearings, etc and spills into the bottom of the crankcase, it should be well over 200 degrees (once the engine is warmed up) even if your gauge shows less than 200, and should be hot enough to evaporate water off.

And even if the oil never reaches 210 degrees inside your engine for some reason, water will still evaporate off and out the breather hose from the hot, aerated oil in the crankcase.

Scott

[KTL]

Frank shared with the forum awhile back the similarity of the internal vs. external t-stat. The only difference is the height of the windows on the regulator body itself (Frank refers to it as the piston) and so the actual thermal regulator unit is the same within the two

internal oil thermostat repair