Oil cooler temperature sensor leaking

Is there a copper washer that’s missing?

Also, how did you apply the thread sealer? When the plug I installed on my new master cylinder wouldn’t stop dripping, I tried that thread sealer. Didn’t work.

I took it all apart, cleaned it with brake cleaner. Re-did the plug with thread sealer, then let it set for 24 hours before I re-bled and re-installed it and it sealed just fine. I figured the brake fluid was dissolving the still-liquid sealer.

Are you sure the threads are leaking and not the sensor just above the threads?

I've never seen "orange" teflon tape, but you could try plumber's (white) teflon tape, just don't run the tape down across the face of the threaded stub - Keep it no closer than 1/8" away from the end of the stub to prevent any teflon pieces from getting in to the oil supply.

If you want things to break, use teflon tape. Teflon makes things too slippery, then you over-torque and break stuff.

Instead, use Permatex thread sealer. Clean parts with brake cleaner, then dry them with compressed air. Let it set up overnight. Impervious to gasoline, oil, etc.

@Gordon Nichols posted:

Are you sure the threads are leaking and not the sensor just above the threads?

I’ve heard tell of people having issues with Chinese knockoff senders/switches leaking between the phenolic and the metal housing.

Loctite 574 will seal most any metal to metal fitting or surface.  I use it on 911 engine's without worrying about leaks at the case halves. But it gets used on other projects as well. It is pricey, but you get what you pay for

Teflon tape insulates senders so they don't have a ground (and they won't work).

Thank you for all the advice. I will look at all the things everyone suggested and post what I find.

Finally got a good day to get the car out. Oil temperature sensor was leaking at the threads. Permatex ultra black gasket maker sealed it up.

Glad to see it was something simple!