Running hot - thermostat

[9dreizig]

Hey guys, was out driving yesterday and the last couple times out I noticed the oil temp was a bit higher than I like it (like 10:00 on the temp guage).
So when I got out of the car last night after a 45 min drive I went to the passenger side to see how the oil lines were and you guessed it COLD!!!
So should I just replace the spring and piston in the thermostate ? Anyone ever done this ? OR should I get the new aftermarket replacement thermostate that Pelican sells?
Thanks

[fredmeister]

I would rebuild the stock unit as it has alot of great features from the factory the simpler aftermarket ones don't.
I bought the replacement thermal unit that drops inside and reused the spring and piston since it was not broken. Mine exhibited the same symptoms as yours.
Works great now
The hardest part is loosening the caps to get at the internal guts and removing the housing assembly form the car without damaging the oil line fittings. Soaked it in rust penetrant for a few days beforehand.
Make sure to use lots of antirust paste on the threads when rebuilding/reinstalling.
Watch out as the caps are under alot of spring tension making it dangerous to remove them and difficult reassembling.

[9dreizig]

Fred,
Do I have to take the whole unit out ? or can I just open the sides and replace the springs ?

[WERK I]

Much easier taking the whole unit out. The cap(s) are easily unscrewed if you put the thermostat in a vise, with the jaws clamped on the cap. Use two blocks of wood to prevent damage to the cap, then tighten jaws down just enough so the thermostat won't slip out. Then turn the thermostat CCW just enough to loosen cap.
Watch out for the spring!

[fredmeister]

I say you cannot do it easily mounted in the car.
I would remove it, mount it in a vise and work on it.
you shouldn't need to play with springs. they are not usually the cause of failure unless they broke. In fact the springs are mostly for pressure relief.
Likely the little thermostatic element inside has failed and is causing the problem. This just drops in as a unit. You need to look at a manual or parts explosion to see how it works to understand better.
Pelican was selling the element when I did mine 2 years ago.

[fredmeister]

I looked up the Pelican online parts manual and it is item 5 "piston" in the oil section of the manual.
It is actually more than a simple piston but a thermostatic cartridge that moves with heat.
Good luck, hope this fixes your problem.

[A930Rocket]

^^^^ +930 on above. I took mine off and apart to rebuild, but when reassembling, one of the large caps galled and I couldn't get it off or on. Ended up buying a new replacement.

[WERK I]

Before disassembling the thermostat, place it in an old pan with hot water (>195*F) in it. You can view down one of the ports and see if the valve is opening all the way.

[Miguel Antonett]

I agree with testing it first... If it doesn't work properly = buy a new one.

[WERK I]

......and test the new thermostat, too.

When rebuilding the 930 engine, I damaged the threads on the old thermostat and replaced it with a new "OEM" thermostat. When going through the break-in cycle of the engine, I noticed the engine would build up temperature slowly over and above normal temps. Before thinking the worst that there was a serious mechanical problem with the engine, I took out the new thermostat and tested it in boiling water and found the port was only opening up about half way. Fortunately, I still had the old thermostat, so I used the paraffin actuator from the old and put it in the new. Tested it and that solved the problem.

[9dreizig]

Guys, I have the thermostat out of the car.. Now the challenge is to get the caps off.. Do I need to undo BOTH of the caps ??
Why test it if I bought the new spring and piston?? What's left to not work ?
Is there a screwdriver or tool to help with removal ?

[fredmeister]

soak it in rust penetrant for awhile.
You may have to use pump pliers on the cap since the intended tool which is like a large screw driver head will likely jump out of the slot when trying to loosen it.
Just break it loose and then undo it with the cap bewteen vise jaws because the spring is under alot of tension and will hurt you if it gets away from you.
I dont know if heating it with a propane torch might loosen the corrosion but try it if you are unsuccessful.

[WERK I]

Todd,
In a previous post I mentioned putting the thermostat in a vise to remove cap. Just place the cap in the jaws of the vise and turn the body of the thermostat with your hands. You'll be surprised how much torque you can generate turning the body versus trying to turn the cap.

Put soft aluminum plates or wood slats in the jaws of the vise to prevent scoring the cap.

[A930Rocket]

I think I made a tool that had a large head to fit into the slot and a long arm to give me leverage. Either that or something that fit in the slot and I turned it with a wrench or something similar.

[9dreizig]

Thanks guys I'll do more battle with it tonight. I still don't understand why would you test something that clearly isn't working ?? And why won't replacing the spring and element fix it ??
Also there are TWO caps one larger and one smaller I assume it's the smaller one that needs to come off??

[9dreizig]

Update guys, went to Napa and got a HUGE screwdriver bit, for my impact wrench,, loosened it in 5 sec!!!
Putting everything back together this morning! I'll let you know