Sandwich Plate O-ring
 

I installed an oil cooler with thermo plate about 2k miles ago and it's leaking. I was scared it was a hose fitting or the thermostat itself, but after a quick look it appears to be leaking from between the sandwich plate and the factory oil cooler. I'm going to reinstall and I bought a new O-ring just in case I actually need it. My question is about the O-ring orientation. Both sides are not the same, and I don't know which way it's supposed to go or even if it matters.

Pics would probably help...

Flat side goes to the mounting surface. Ribbed side goes to the plate. Do not oil it.

Thanks for the reply. I did oil it last time. I did it because in my mind it was similar enough to the seal on an oil filter to make me do it. What's the reason to not oil it and can this be what's causing my leak?

Instruction say not too. Not sure of the reason.

cool, thanks for the info

You need lube if the parts screw together (relative motion between gasket and mating surface) to prevent the gasket/o-ring from scrunching up. Not usually necessary if they bolt together.

How much leak are we talking about? My thermo plate/hose ends have an occasional drip. Replaced the o-ring, fittings, hose ends, and trimmed the hoses for fresh endings, all for naught. I've come to accept that that is just the way things are gonna be...

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This was my line of thinking at first, but if you think about it the oring on the sandwich plate is stationary between the plates while it's being installed, but the oring on the oil filter does screw on (my original way of looking at it was wrong)

Too much. There was a decent size puddle that had collected on the undershield, and it had started to splash on the passenger side exhaust

That's definitely too much oil. Have you run the engine with the bumper off and gotten a firsthand look at where the leak is occurring? If it's splashing on the exhaust that sounds more like a spray.

Curious if you tightened the plate down to the proper torque.. the first time, I didnt want to buy a 1 inch socket and went the cheap route of using a 1 inch wrench.. needless to say it wasnt torqued down properly and I had a leak at the mating point between plate and stock oil cooler.

For what it's worth, my o-ring is lubed with the ridged side facing the stock oil cooler and I've had no leaks from that element of the system.

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So I finally had a chance to get her up in the air today, and I can confirm that the leak is coming from between the sandwich plate and the OEM oil cooler. I went to swap out orings and the one I ended up taking out has a big gouge on it side that rolls into the edge. I replaced the oring, put on my oil cooler block off cover and installed the tee for my Defi oil pressure sensor while I had her up. I wanted to add a tee for the temperature as well, but the threads for the OEM oil temperature probe are not 1/8bspt (the ressure switch is) so I couldn't use my other tee that I bought :shakes head:

I'll add some pics when I get home

Adding pics

Does anyone know the correct thread size for the OEM temperature probe?

This is what I have https://www.z1motorsports.com/an-ada...ng-p-5328.html

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Defi is a quality sensor fyi. Be sure to use loctite thread sealant on the threads for the adapter, sensor, and oem sensor. The oem sensor fits on the end of the adapter. This setup does place it in the swing path of the sway bar but there shouldn't be any contact in normal or spirited driving conditions.

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