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

[Casa de Mesa]

I picked up my oil filter housing, coolant thermostat housing and a few miscellaneous engine parts from the cerakote coater yesterday. Cerakote can be applied with an oven (typical) and also there is a formulation that cures at room temperature or slightly above. I specifically asked for the latter - room temp cure. However, it appears the coating place either baked the parts to remove any oils, or used the oven cure the Cerakote.

What I am now worried about are rubber or nylon or any nonmetallic o-rings inside of both of these pieces - the coolant thermostat housing and oil filter gasket housing.

My questions are twofold. First, does anyone know if the oil filter housing has internal plastic or rubber o-rings/seal? From looking as closely as I can it does not appear that's the case. However, I am worried that the oil thermostat inside of the oil filter housing may have been heated to the point of damaging that thermostat.

Second, the o-ring/seal inside of the coolant thermostat housing has deformed and no longer will seal against the thermostat once the actual thermostat is put inside of that housing. My thought is either to 1) simply remove that o-ring/seal and put everything back together, or 2) get a new thermostat housing. If I just remove that o-ring/seal it would leave a pretty nominal sized gap around the outside of the thermostat and allow coolant to flow through prior to the thermostat opening at operating temp. What I'm wondering is if that will cause any issues besides the motor taking a longer time to heat up? For example, being that close to the water pump I'm worried about cavitation occurring on the outside of that thermostat because the seal is no longer there.

I will find out on Monday when this shop opens back up how hot exactly these parts got. Pretty disappointing when I left very explicit instructions...

[Arith2]

I'm 100% the oil filter housing thermostat will only come with a new housing. I think they run $800 new. Maybe $250 used. It would be good to know if they baked your parts because Cerakote is cured at like 500° F. I am very confident thermostat is damaged if that's the case.

[sapote]

There is a check valve in the oil filter housing.

[sapote]

What I'm wondering is if that will cause any issues besides the motor taking a longer time to heat up

If it leaks via the deformed O-ring with the Tstat in closed position, then it will not reach operating temp on FWY in cool weather.

[Casa de Mesa]

There is a check valve in the oil filter housing.

Thanks sapote. There seems to be either:
- 3 check valves, or
- 2 check valves and 1 thermostat
I'm not sure which.

Are you saying the oil filter housing does not have a thermostat? And if so, I might be OK?

Regarding my coolant T-stat, that was my fear. Sounds like I'm in it for a new t-stat housing, which sucks cause this one looks pretty fantastic coated...

Arith2 thank you too. The info I found shows Cerakote curing at 250F or 300F. However, I'm worried prior to coating, they baked the oil out of the parts, as I overheard them talking to another customer when I picked mine up and they were describing how they were going to clean up his parts. The final step is degassing/baking. That comment stuck with me and when I started unpacking things this morning, I saw evidence of "shit got hot".

[sapote]

I'm concern the check valve(s) are plastic and deformed useless. If the Tstat is in the OFH then it's damaged too (leaked out all wax).

[sapote]

I am worried that the oil thermostat inside of the oil filter housing may have been heated to the point of damaging that thermostat.

The Tstat is at the bottom of the gasket side. Take it out and test in boiling water. The same for coolant Tstat.

[Casa de Mesa]

Disassembled the oil thermostat and cleaned the housing as best I could. There is definitely evidence of the wax leaking out. Not a large amount, but this oil thermostat is pretty small.

I can pull the thermostat piston out (with my hands) and it makes me wonder if I can find some replacement wax. That's likely not a viable solution, but would be nice to salvage this housing. It is beautiful with this coating on it...

Also the check valves appear to be ok. I used MAF cleaner to get it as clean as possible. Pics below. But it's impossible to say for sure. I'd disassemble the whole housing, but have no clue how to get at the check valves inside the filter housing. There are 2 at the bottom of the bowl where the actual filter goes in. The work in opposing directions.

I regrettably think I'm in for a new coolant t-stat housing and oil filter housing. So irritating, as I was extremely clear in my reasons for using the room temp cure Cerakote.

[Rosie]

It might be worth seeing if the E39 M5 Thermostat Seal fits rather than throw the housing away:-

https://www.fcpeuro.com/products/bmw-engine-coolant-thermostat-gasket-n-a-m5-z8-11531312287oe

And, I’m not sure if this will work, but again, it might be worth a try, is the injection thermostat from an old Mercedes:-

https://www.fcpeuro.com/products/mercedes-engine-coolant-thermostat-mahle-behr-0012039575

(The wire retainer comes off before installion)

[heinzboehmer]

Maybe get a good used oil filter housing and swap the parts over?

[sapote]

There is definitely evidence of the wax leaking out. Not a large amount, but this oil thermostat is pretty small.

I can pull the thermostat piston out (with my hands) and it makes me wonder if I can find some replacement wax. That's likely not a viable solution, but would be nice to salvage this housing. It is beautiful with this coating on it...

There are 2 at the bottom of the bowl where the actual filter goes in. The work in opposing directions.

* The wax motor cannot be refilled properly with the correct volume.
* the right side valve is the check valve to prevent pumped oil drain back, and the left valve I believe is the pressure relief valve when filter is clogged up. M3 has metal valves so they might be still ok. Non-M has the plastic check valve.

Edited: the high temperature trauma might have weaken the springs, and so the relief valve might be too weak and bypass the filter and you don't want this happens.

[Casa de Mesa]

It might be worth seeing if the E39 M5 Thermostat Seal fits rather than throw the housing away:-

https://www.fcpeuro.com/products/bmw-engine-coolant-thermostat-gasket-n-a-m5-z8-11531312287oe

And, I’m not sure if this will work, but again, it might be worth a try, is the injection thermostat from an old Mercedes:-

https://www.fcpeuro.com/products/mercedes-engine-coolant-thermostat-mahle-behr-0012039575

(The wire retainer comes off before installion)

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...

Maybe get a good used oil filter housing and swap the parts over?

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.

* The wax motor cannot be refilled properly with the correct volume.
* the right side valve is the check valve to prevent pumped oil drain back, and the left valve I believe is the pressure relief valve when filter is clogged up. M3 has metal valves so they might be still ok. Non-M has the plastic check valve.

Edited: the high temperature trauma might have weaken the springs, and so the relief valve might be too weak and bypass the filter and you don't want this happens.

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.

[Casa de Mesa]

My pain continues:



This was in stock last night. Hit refresh on my browser, and boom a 2-3 weeks ETA. There must have been a run on these things over night...

[Arith2]

In this case, I'm glad to be wrong. The oil filter housing easily gets to 250 degrees during operation. Think about track cars. I doubt that would've caused it.

You also have to think that the manufacturing of the housing may only be financially feasible if everything is installed together. Think about how often that thermostat goes bad, almost never. It doesn't make sense to manufacture it by itself from a business standpoint. I agree that tossing parts is stupid and we should go back to repairing them, however, this one doesn't seem to fall into that. The parts are too reliable and damage is pretty much the only reason to replace the housing. I'll ask tomorrow if my parts department can get one sooner.

[sapote]

Think about how often that thermostat goes bad, almost never.

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.