Aux oil thermostat removal (Solution)

[SchnellSchweitz]

I have had issues with heat and burning oil since rebuilding my engine, but have since traced this issue to a non-functioning auxiliary thermostat.

I just wanted to share a solution I came up with to remove the aux thermostat safely and relatively quickly... I call it the Jack Assist Method.

If you are having heat issues with your engine and all vacuum leaks have been eliminated, it's "possible" it may be a bad auxiliary thermostat. In my case, I traced this issue by researching this very site for solutions.

Once I found the issue was the aux thermostat, I researched removal and found many folks were cutting their lines to remove it. I actually crimped one of my lines while attempting my removal, but I may have found a solution to avoid this issue next time around. Hopefully, others find it useful.

First off, as many have described in this forum, the nuts are real PITA to get off. Probably tougher to get off than a broken delvar.... just because of the lack of space you have to work in.

My solution - With the rear of the car resting on jack stands, I positioned an adjustable wrench on the outer rear nut attached to the thermostat so that my 3 ton jack could lift on the handle of the wrench. This broke the seal and allowed me to remove it by hand with no damage to any oil tubes. I used the same method for the inner rear nut. It took me about 20 minutes of careful alignment and slow jacking to do, but worked like a champ.

I should add, I shoved a standard sized adjustable wrench into the separation space between the top of the thermostat and the inside fender wall to keep the thermostat from rotating. I think any similar size object would work... just so the thermostat has something to block it from rotating.

The forward thermostat lines were a different story. Since the nuts on those lines turn horizontally, and are too far forward to use any kind of jack assist, I did these by hand. However, I will not do this the same way again. I actually crimped one of the lines by doing so.

I found the best solution for removing the front two lines is to remove them at their connections over the front passenger tire and take the lines and the thermostat out together.

I believe this is the best way to remove the auxiliary thermostat and I didn't see this method mentioned elsewhere... Although it may have been and I just missed it.

Anyway.... that's my contribution to the group for the week.

Eric J.

[JT]

Are you talking about the internal oil cooler thermostat? The one that sits on top of the cooler near #6 cylinder? I thought it was held in by a couple of 8 or 10mm nuts and an O-ring. If that's the one you are talking about (part # 930 107 765 00) I'm totally confused.

I may be removing mine in a couple of weeks, so this information could be critical. Help me understand. I likewise have a 3.0 liter.

[SchnellSchweitz]

This info is for the external or auxiliary oil thermostat. It does not pertain to the thermostat on the engine.

This one is located in the rear, right wheel well.

Eric J.

[JT]

OK, that makes a little more sense, but I didn't have that big of a problem removing my Mocal. I used a large adjustable wrench on the nuts and a pipe wrench on the thermostat to keep it from moving.

Thanks for the quick response.

[SchnellSchweitz]

My external thermostat had not been removed since the factory install. Perhaps there are fewer cars out there like mine. But there was no way in *ell I was getting mine off without some extra help.

PS - I used plenty of PB penetrating fluid... and still needed the jack.

[boyt911sc]

Schnell,

How did you come to the conclusion that the auxiliary thermostat was the problem for your over-heating? What test did you perform to verify your finding? Thanks.

Tony

[SchnellSchweitz]

Early indications:

Engine runing too hot in general. Intermittently, it would run at an acceptable temp.

Heat was being transferred to the engine bracket. (became too hot to touch)

Oil pressure was very high (never decreased).

Oil was being pushed out of my air intake.


Final indication:

The trombone cooler, under the front right fender, wasn't getting hot.

Hope this helps.

Eric J.