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Discussion Starter · #1 · (Edited)
Over the last year and a half, I've replaced gaskets on my 2010 535i xDrive for the OFH/OC, VC (VC itself was also replaced) and oil pan. Gold star for me and my pristine N54, right? Wrong! For whatever reason, the oil just goes looking for the next place to escape from... the oil cooler thermostat cover.

Now, this should be the easiest, cheapest fix on the N54 - two torx bolts that are easily accessible without removing anything else and pop in a new gasket. Another gold star! Nope. It seems that the gasket is not sold separately. A billet cover with gasket is available or you can replace the whole thermostat housing. I would prefer not shell out for either of those solutions - just on principle!

Somebody on one of the 3 series forums found a third option - a m3x37 o-ring fits just perfectly! Looks like viton o-rings are easy to source on the internet, but I'm in Canada and something about paying $40 US ($1,000 CDN approx.) In shipping for a $2 item doesn't feel right - again, it's the principle!

My question(s): has anybody used another solution to successfully cure seepage at the OC thermostat cover? Or, does anyone know of a retail source for viton o-rings in Canada?

Thanks in advance!
 

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Discussion Starter · #3 ·
Sorry, I should have been clearer... I already replaced that gasket (i.e., between the OFH and the OC thermostat housing), which I identified on realoem and ordered from fcp. ;)

The gasket I need is the one behind the plate at the left (looking from the front of the car) of the thermostat housing. It is octoganal-ish (or a square with cut corners?) in shape and is not listed on realoem...

See here:
4 F1 C06 B0 1 AC4 4041 96 CD 916538 F5 E92 D — Postimages
 

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Discussion Starter · #6 ·
If I were the sensitive type, I might think you are questioning my Google-fu, but i choose to assume positive intent. As I mentioned in my original post, I am aware of the billet options and the o-ring solution from the 3 series guys. I don't want to spend half the cost of a new housing on the billet cover. (Plus, I would like to maintain OEM look.) My preference is to use an o-ring, but with shipping to Canada, it costs the same as a billet cover...

Does anyone know of a retail source for viton o-rings (specifically m3x37) in Canada?
 

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If I were the sensitive type, I might think you are questioning my Google-fu, but i choose to assume positive intent. As I mentioned in my original post, I am aware of the billet options and the o-ring solution from the 3 series guys. I don't want to spend half the cost of a new housing on the billet cover. (Plus, I would like to maintain OEM look.) My preference is to use an o-ring, but with shipping to Canada, it costs the same as a billet cover...

Does anyone know of a retail source for viton o-rings (specifically m3x37) in Canada?
Could you share what you ended up doing for this thermostat cover leak issue? I tried 3x37 o-ring which didnt stop it. Not sure what I am doing it wrong. Maybe I am tightening it down too much that its becoming flat.
 

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Discussion Starter · #8 ·
I haven't addressed it yet. It is just barely seeping, so I am content to leave it for now while I attend to the Princess' more pressing needs: condensation sensor, rear window rubber seal, VANOS solenoids, new plugs, hood release cable, headlight restoration...

I will update when I get around to addressing the gasket on the oil thermostat cover. In the meantime, I am open to suggestions...
 

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I haven't addressed it yet. It is just barely seeping, so I am content to leave it for now while I attend to the Princess' more pressing needs: condensation sensor, rear window rubber seal, VANOS solenoids, new plugs, hood release cable, headlight restoration...

I will update when I get around to addressing the gasket on the oil thermostat cover. In the meantime, I am open to suggestions...
Hello, fellow Canadian here, did you ever solve the gasket sourcing issue? I’m getting a used oil thermostat housing and I’d love to be able to replace the gasket if I need to!
 

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Here is the part # for the oil line o-rings and also size:
Rectangle Font Circle Brand Logo

I got this from realoem.com

You can find about any part # you need - you need the last 7 characters of your VIN
 

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Sorry, I was referring to the o-ring for the oil cooler thermostat where the thermostat is housed. There is no part number for it on real oem as they don’t sell replacements for them as far as I know. There’s someone in Australia selling home made ones but the shipping is quite high. There are some people who found a generic o-ring that works for some and not for others so I’m hoping to find out if anyone in Canada has figured out where to source these yet. Thanks!
 

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Sorry, I was referring to the o-ring for the oil cooler thermostat where the thermostat is housed. There is no part number for it on real oem as they don’t sell replacements for them as far as I know. There’s someone in Australia selling home made ones but the shipping is quite high. There are some people who found a generic o-ring that works for some and not for others so I’m hoping to find out if anyone in Canada has figured out where to source these yet. Thanks!
Well, I'm stumped. I didn't know there was an engine oil cooler thermostat. I've learned something, I guess. Where is it, on the oil filter housing or at the actual oil cooler?
 

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Motor vehicle Automotive tire Automotive design Vehicle Automotive exterior

this is the gasket I’m looking for, it’s where the oil thermostat is housed. It’s in front of the oil filter housing. The automatic N54s came with it and the manuals didn’t unless you spec’d it. I think they still use this design on N55 and S55 bmw engines. The bottom lines run to the actual cooler thats in the passenger side wheel well on LHD cars.
 

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I had no idea that was there! A long time ago when we needed an odd gasket we'd buy a sheet of gasket material and trace the old one. That probably wouldn't work here, tho.
Question:
Is there any reason a flat sheet of gasket material couldn't be cut square to cover the entire opening to seal it? I suppose the cover protrudes into the housing...
 

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I had no idea that was there! A long time ago when we needed an odd gasket we'd buy a sheet of gasket material and trace the old one. That probably wouldn't work here, tho.
Question:
Is there any reason a flat sheet of gasket material couldn't be cut square to cover the entire opening to seal it? I suppose the cover protrudes into the housing...
yeah I make most of my gaskets out of gasket material but this one has to be resilient to extreme temperatures and not be affected by oil. I just wanted to know if a few other people have tried the generic o-ring replacement with any success. But thanks for the input!
 

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The gasket in the link from post 5 works for those who have tried. The gasket corners are soft enough that a round gasket will be fine.
Thank you, this is the answer I was looking for. I wanted a second opinion to make sure it did work. Other people haven’t updated other forums so the info is somewhat old. Good to know!
 

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Discussion Starter · #18 ·
Thank you, this is the answer I was looking for. I wanted a second opinion to make sure it did work. Other people haven’t updated other forums so the info is somewhat old. Good to know!
Sorry for the late reply. Mine seems to be only weeping ever so slightly, so I have deferred replacement until I can source a solution at a reasonable cost. I was looking for a Viton o-ring for the job but haven't had any luck finding a retail source in Canada. Let me know what you come up with.
 

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Sorry for the late reply. Mine seems to be only weeping ever so slightly, so I have deferred replacement until I can source a solution at a reasonable cost. I was looking for a Viton o-ring for the job but haven't had any luck finding a retail source in Canada. Let me know what you come up with.
All good, ah gotcha. Yeah I’m struggling to find much in Canada... I’m going to try that 43 diameter x 3 thickness gasket for now, my current oem gasket is really flat, I wouldn’t be surprised if it would leak as is. I’ll keep you posted as soon as I find a reliable solution within Canada. I can easily hop the boarder and get some in the states but with everything going on now it’s hard to cross for no reason.
 

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I admittedly just skimmed this topic. Sorry if it's been covered.

There are three main seals on the oil filter housing that tend to leak:
1) engine to oil filter gasket
2) oil filtee housing to oil cooler gasket
3) the two o rings that connect to the oil lines coming from the fan/radiator assembly.

For 1 and 2, there are updated part numbers. They are made in japan, that's how you can tell. I think they are only sold under BMW.

For 3, you can replace the o rings with a new equivalent gasket but it's unlikely to fix the issue. Either use thicker gaskets, or use some rtv silicone. You can remove the two top plugs to give you plenty of access to clean the area with brake cleaner or equivalent to get the oil off. Then gasket, rtv, let ot dry, reassemble, and you should be good to go.
 
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