Oil filter housing internal o-rings and Thermostat housing o-ring

[Arith2]

What is the lifetime of the engine coolant Tstat? I'm sure every M3 already gone through one unit. The oil Tstat design concept is the same as any coolant Tstat -- using the wax motor with a moving shaft, and the many movement led to leaking the liquid wax out, then it no longer can open.

Springs do also wear after about 7 years but are there and real negative symptoms to it failing? What you say makes sense but unlike a coolant thermostat, it doesn't seem to destroy an engine. On the contrary, maybe we just uncovered the secret killer of the rod bearings

[SoloTSi97]

Hey Rosie - thank you for both of these suggestions. I just added the first link to (t-stat seal) to my FCP shopping cart. For $20, it's worth trying.

On that Merc oil thermostat, the design/dimensions appears to be much different than what's in the S54 housing. However, you've given me an idea and I'm going to start searching.

I really hate how BMW screws us sometimes with parts that should 100% be serviceable but are not. They then become paperweights because they don't offer replacement sub-components. There is no reason why they shouldn't make these housing completely rebuild-able.

I'm not a tree-hugger, but is does kill me how much crap we toss out that should have an infinite service life with a little regular maintenance. Such a waste...



fleaBay and other sites list these things for about $350-380. For that money, I'm going new. Zero worries about if the motor overheated and the t-stat in the used one is screwed.

That said, I'm going to try to get mine full disassembled today. What do I have to lose at this point? Will report back with any findings.



I figured as much about the wax.

The right side valve does appear to have a black valve seal. I tried to capture it in the photos - you can see it on either side of the spring retainer on that zoomed-in pic. So my thought is it's plastic of some type. When I fill the bowl with MAF cleaner, it holds the liquid and does not allow it to seep down. However, now that I've slept on this, the more I think this is one part I don't want to take a gamble with. I had the same thought about the springs.

So my FCP cart has both of these housings sitting in it. What a waste!

Thanks very much everyone. Greatly appreciate the replies.

I know I'm reviving an old thread but I suspect more and more folks will start to experience this and come looking for an answer, particularly how that the thermostat housing is NLA.

Casa de Mesa any chance you actually explored using that alternative thermostat housing seal? Mine's no longer sealing and the housing is no longer available so I'm looking for alternatives. Thanks!

[Casa de Mesa]

Casa de Mesa any chance you actually explored using that alternative thermostat housing seal? Mine's no longer sealing and the housing is no longer available so I'm looking for alternatives. Thanks!

Yes I did, given the relatively nominal price, and meant to come back to here to update the thread.

The seal did not fit, wasn't even close. I can try to get pics this weekend.

[SoloTSi97]

Yes I did, given the relatively nominal price, and meant to come back to here to update the thread.

The seal did not fit, wasn't even close. I can try to get pics this weekend.

Thanks much for the reply! At least it rules out that avenue. My local dealer parts guy says there are zero housings in the US and zero in Germany so new ones are for sure NLA. Guess I'll take my chances with a (hopefully lower mileage) used one if I can find such.