Thermostat housing O-ring

[SoloTSi97]

I had one on order for months and cancelled it in the end.

It's probably worth getting a secondhand one just to confirm it fixes the fault, with a view to getting a new one at a later date.

Yeah, my local parts guy said he saw zero in the US and zero in Germany. I'm not sure if there will be more at a later date or not.

So yeah, I think the hunt for a good used one begins!

[ac427]

149k on the clock here. I don't think it's a common failure point (yet) but it stands to reason a seal could over time degrade I guess. I'm not sure the history of mine but it pretty clearly doesn't seal fully against the thermostat housing.

I had one on order for months and cancelled it in the end.

It's probably worth getting a secondhand one just to confirm it fixes the fault, with a view to getting a new one at a later date.

[SoloTSi97]

How many miles has your car done?

Mine has done 180k miles on the original thermostat housing. Perhaps yours got damaged or had a manufacturing defect.

149k on the clock here. I don't think it's a common failure point (yet) but it stands to reason a seal could over time degrade I guess. I'm not sure the history of mine but it pretty clearly doesn't seal fully against the thermostat housing.

[ac427]

Sorry to revive an old thread but any idea if there's a solution to this? The seal in my housing is shot and no longer seals against the thermostat. Turns out, that's probably been the cause of my "implausible temperature" codes for a while now. But, the housing itself is NLA ... dealer confirmed that there are zero in the US & zero in Germany. Of course, I can source a used one but that's going to be a bit of a gamble (that's only going to get worse as these cars continue to age).

Any chance some enterprising soul in the aftermarket has come up with a viable solution here?

How many miles has your car done?

Mine has done 180k miles on the original thermostat housing. Perhaps yours got damaged or had a manufacturing defect.

[SoloTSi97]

Sorry to revive an old thread but any idea if there's a solution to this? The seal in my housing is shot and no longer seals against the thermostat. Turns out, that's probably been the cause of my "implausible temperature" codes for a while now. But, the housing itself is NLA ... dealer confirmed that there are zero in the US & zero in Germany. Of course, I can source a used one but that's going to be a bit of a gamble (that's only going to get worse as these cars continue to age).

Any chance some enterprising soul in the aftermarket has come up with a viable solution here?

[chris719]

So is the housing worth replacing at 100k due to this seal or is it just a waste of time?

[stephen]

Well this sucks. I had one on order at my local dealership since reading this thread in September. Now appears to be NLA.

[George Hill]

The thermostat drags against this seal as it opens in the s54, it’s an interesting design. When you remove an old thermostat, you should see witness marks from where the seal rides.

You are absolutely correct, bad memory on my part, thanks for correcting me.

[Bry5on]

The thermostat drags against this seal as it opens in the s54, it’s an interesting design. When you remove an old thermostat, you should see witness marks from where the seal rides. Interesting that most thermostats I’ve seen now didn’t open completely straight, based on the witness marks.

If one fell out, that would be a time to replace with a new one! Good call there, that would be hard to debug.

[George Hill]

It appears to be a carbon impregnated PTFE (Teflon) wiper seal. I wouldn’t expect much if any wear, although ... As long as there’s no debris in your cooling system, this should last the life of the engine.

The thermostat doesn't move against the seal except for when it is installed so I wouldn't think it would wear at all? My biggest concern is that it would loose its tension against the thermostat housing. I don't know if that is a realistic concern but I have seen the seal fall out (and it was not reinstalled whether on purpose or accident and boy did that create a huge headache to figure out). I've also seen (2) cars have coolant temp plausibility faults until the seal/housing was replaced.

...I did replace my tstat housing at 180k miles to rule this out as a failure mode. Pressing a thermostat into a new housing should feel noticeably more difficult than a used housing as the teflon is permanently deformed...

I along with you generally prescribe to replacing parts as a preventative rather than because it has failed.

[Bry5on]

It appears to be a carbon impregnated PTFE (Teflon) wiper seal. I wouldn’t expect much if any wear, although I did replace my tstat housing at 180k miles to rule this out as a failure mode. Pressing a thermostat into a new housing should feel noticeably more difficult than a used housing as the teflon is permanently deformed. As long as there’s no debris in your cooling system, this should last the life of the engine.

[ac427]

Its not a o-ring, its a lip seal like a crank seal. BMW doesn't list the S54 separately.

This is a for an S62, same idea, maybe its the same part, IDK off the top of my head: 11531312287

Thanks for the part number George.

https://www.realoem.com/bmw/en/showparts?id=EJ11-EUR-12_1998_E52_BMW_Z8&diagId=11_5265#11531312287

It could be the same seal but the housing is definitely different.

[George Hill]

Its not a o-ring, its a lip seal like a crank seal. BMW doesn't list the S54 separately.

This is a for an S62, same idea, maybe its the same part, IDK off the top of my head: 11531312287

[jayjaya29]

Is there actually an oring in there?

[ac427]

Really, I never knew that; to be fair, I rarely ever from ecs/fcp; I buy all my parts via Worldpac and get them the same or the next day , which is super nice since the m3 is my daily.

If you really need a thermostat housing gasket, I have one right now that I thought I would need since I had dried coolant all over the bay (I pressumed I had a coolant leak and was going to replace all the gaskets b/c that's what I usually do lol), which turned out to be my rad having a hole in it.

That's very kind of you. I'm going to do some more research first but i may take you up on the offer.