I pulled my thermostat to check and replace the gaskets and found that the gasket that seals the outer edge of the thermostat to the inner wall of the housing was badly deteriorated and, in fact, broken in one section. I pulled this piece off, photographed it, and set it aside, thinking it would be easy to find a replacement.





Realoem.com makes no mention of this part anywhere in the diagrams, and information on Google is sparse.  Some people were discussing somewhere that the thermostat itself can be replaced with one from a '94 Toyota Corolla though the overall length goes from something like 30mm to 35mm.  Diameter is the same.  A quick trip to my local Autozone got me a gasket for the Corolla thermostat (#35292) which fits the K100 thermostat like a charm.  The problem is that it is slightly thicker in all dimensions such that it will not seat properly inside the housing.

Does anyone know where a suitable replacement can be found?  Do I need to just cut this one down or compress it somehow?

Thanks!

there are 3 versions of the gasket that I have found , all varying in thickness and width ...still to try the thinnest wall version, as you say the overall thickness difference between the thermostat and outer wall of the housing is quite small ,,,maybe 2.5- 3.00mm overall

I would guess a slight cut in the external diameter would not overly affect the operation ,,,what could be important is the thickness (width ) of the seal to allow for good location of the mechanism behind the retention fitting of the cover without too much pressure and maintain a good seal around the front of the housing cover.

Hi there
During last year's bike maintenance, was time to replace the cooling mixture and check the system components, everything was ok but when reinstalling the thermostat found that the internal gasket (not the oring) had swelled and will not fit. The diameter had increased about 3mm, perhaps due to the cooling mixture components.
Searching on google found that by heating the rubber it would shrink, try with a heat gun and boiling water with no succes.
Finally baked it in the convection oven at 350ºF by around 30minutes (checking it every 5 not to burn it) and came out at original size without loosing flexibility nor distorted.
Hope this helps
Best regards
JA

@japuentes

That sounds like a sound solution in your case, but what I believe may have happened is that baking the gasket evaporated whatever solution worked its way into the rubber that caused it to swell.  The gasket that I purchased from Autozone is already at this increased size, and I'm not sure that baking it would reduce the size.  I can't imagine it would hurt though!

I see a o-ring seal on RealOEM. The part number is: 17111460718

There's a guy selling them on eBay.

http://www.ebay.com/itm/BMW-motorcycle-17111460718-Thermostat-housing-O-ring-Nos-K-models-47-29X2-62-/151161381142

I don't think this is a hard part to find.

Regards

I replaced my thermostat a few months ago. Cannot recall a gasket of the type you indicated. I am presuming the gasket you are referring to was on the radiator side of the thermostat. There was a o-ring that went on the cover. I will check my invoice to see if there was another gasket as the details are somewhat foggy.

@tgolden

It is my understanding that this part you're referencing is the o-ring that seals the housing cover, not the gasket that seals the edge of the thermostat.  The first image I posted above points to the part I'm referring to.

I don't see that there are two seals in the area of the thermostat. I checked RealOEM, a parts microfiche and the bound parts book.

It's interesting that there are no pictures of this "second" seal.

Did you have two seals when you disassembled it?

Call a BMW dealership and ask the parts guy about it.


Regards

tgolden wrote:I don't see that there are two seals in the area of the thermostat. I checked RealOEM, a parts microfiche and the bound parts book.

It's interesting that there are no pictures of this "second" seal.

Did you have two seals when you disassembled it?

Call a BMW dealership and ask the parts guy about it.


Regards

The other possibility is the thermostat has a gasket bonded to it rather than as a separate piece. When you blow up the picture on the microfiche it sort of looks like there is a raised gasket like edge. In which case, there wouldn't be a separate part #. Perhaps someone can get a picture of a replacement thermostat in-box and post it?

I see a picture of a seal that appears to mount on the thermostat's large disc or that it appears the large disc is fitted into an inside slot in this seal in the Haynes manual.

You may be able to make the one you got from an auto parts store fit if you adjust the dimensions with some abrasive paper. Perhaps you've got to buy a new thermostat to get that seal.

If you go back to the auto parts store, they may be able to find you one that fits better.

Apparently, this isn't an individual part in the BMW system. I think it should be.

Regards

I agree that it should be as well!

If you check this post, robmack's first image shows the o-ring on the housing cover and his second image shows the gasket that surrounds the thermostat itself.

Any place I've seen an OEM or aftermarket thermostat does not have this gasket.

I'd make the gasket for the Corolla fit. I'd also replace the o-ring for the cap.

Call a BMW parts store and ask for a solution.


Regards

Motorworks lists two seals for the thermostat. A coolant thermostat u-seal and coolant thermostat cover o-ring.

https://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=40&Ct=GA&SbCt=BA_15_40_GA_70

Order it from Motorworks.

Regards

@diesputnikdie

The Idea came to me from someone in the web who claimed to do it to resize oversized rubber gaskets. I think that is worth to try and let us know.
Best regards
JAP

Motobins list this

 as a WATER CAP INNER FLAT RUBBER INNER SEAL K`s (NOT K1200)
 and this

as THERMOSTAT K`s (NOT K1200)


Wondering if the first (WATER CAP INNER FLAT RUBBER INNER SEAL K`s (NOT K1200)) is the black ring clearly visible on the second?

Euro Port Parts list a thermostat u-seal that may fit.



Engine Coolant Thermostat Seal Part Number: 225 33099 071 Manufacturer: REINZ


The price is $1.06 which is better than Motorworks. It will be USA shipping as well.



http://www.europortparts.com/

Enter the part number in the website part # search box.



The dimensions aren't indicated, but I suspect it will fit. Contact them and inquire.


Regards

tgolden wrote:Euro Port Parts list a thermostat u-seal that may fit.

Engine Coolant Thermostat Seal Part Number: 225 33099 071 Manufacturer: REINZ

...

Nice find!  That looks like it's the one   

Ordering ASAP.

Let us know if it fits.

Regards

Victor Reinz is one of the largest automotive seal manufacturers. If this seal doesn't fit, then they likely make one that does. Find a store that has a Victor Reinz catalog that can look up the seal by its dimensions.

As you can see in post 15, there's a single gasket that seals both sides.  BMW part # 17111460718.  About $7 at Ride West.

#4:

I think BMW part # 17111460718 is the thermostat cap o-ring seal.

The seal that he needs is the thermostat u-seal that's not listed as an individual BMW part.

Motorworks sells this second seal in the UK. See post 13. We'll have to wait and see if the thermostat u-seal that Euro Port Parts sells fits.

Regards

klamityboy wrote:Motobins list this

 as a WATER CAP INNER FLAT RUBBER INNER SEAL K`s (NOT K1200)
 and this

as THERMOSTAT K`s (NOT K1200)


Wondering if the first (WATER CAP INNER FLAT RUBBER INNER SEAL K`s (NOT K1200)) is the black ring clearly visible on the second?

The rubber seal in the top picture is for the radiator cap, not the thermostat cover or thermostat.

Apparently, BMW doesn't sell the rubber seal you see on the second picture of the thermostat. There's no individual BMW part number for that seal that I can find.

Regards

I was curious so I opened up a K75 radiator I had lying around and the only two seals are the cover O-ring and the one that goes around the lip of the T-stat.  The second one probably comes with the t-stat which is why it's not a separate part.

I think a viable workaround would be to just put a rubber washer on each each side of the t-stat.

I know where you can get a good used one in Seattle for a sixpack of Heineken. 

You might be worrying too much. Some have drilled holes in the 'plate' to keep some circulation over the radiator. If it leaks a bit it doesn't matter too much, it'll just takes a (tiny??) bit longer for the bike to get to its normal operating temperature.

duck wrote:I think a viable workaround would be to just put a rubber washer on each each side of the t-stat.

I think the original seal stabilizes the position of the thermostat and protects the plastic radiator case from being cut, scraped, or otherwise damaged by the large thermostat flange due to vibration effects. If the Euro Port Parts thermostat seal is a good fit for only $1.06 plus shipping, then I think that's the best solution short of buying a new thermostat. A rubber washer on each side may not protect the plastic enclosure from the thermostat flange metal rim.

true rene ....it operates in bypass mode till it warms up any how

diesputnikdie wrote:

tgolden wrote:Euro Port Parts list a thermostat u-seal that may fit.

Engine Coolant Thermostat Seal Part Number: 225 33099 071 Manufacturer: REINZ

...

Nice find!  That looks like it's the one   

Ordering ASAP.

I checked the shipping charges and Euro Port Parts wants $11.67 for UPS Ground shipping. Total cost would be $12.73.

Motorworks (UK) wants £13.99 or about $23.32 in US Dollars for delivery to USA for the one they sell that they advertise as a direct fit for the K-bike.

Do a Google search for the 225 33099 071 part number. There are several places that sell it perhaps with reasonable shipping charges. There's a guy on eBay that's selling it for $4.95 w/ free shipping.


Some of the websites selling this thermostat seal list the application as a 1998 Mercedes E300. Check your local parts store to see if they have it under that vehicle listing. It would be better to check the fit before you buy.



Regards

If anybody knows the dimensions for this thermostat u-seal, please post them. The dimensions, preferably in mm, would be helpful to locate a suitable replacement.

Regards

I checked my invoice when I replaced the thermostat and it was definitely a single part for the thermostat with integrated gasket. The supplier is very anal about quantities of parts so if the single part number consisted of a thermostat and separate gasket it would have shown the part # and then # of pieces 2. I think I read in another post that someone, perhaps Robmac, had replaced their thermostat with one from a local auto supply store. They might have experience with a non-gasketed version being installed. If a non-gasketed version is used does the diameter need to be increased to stop the thermostat from moving and damaging the walls of the hose? Of course this begs the question, if the gasket originally enveloped the metal edge of the thermostat and deteriorated to the point of appearing as a gasket on only one side of the thermostat, will the deteriorated gasket material cause an issue in the radiator or water pump?

I wouldn't recommend replacing the original rubber u-sealed thermostat with a substitute non-rubber u-sealed version due to concern that vibration and the thermostat metal flange would cut into the plastic surroundings. Some substitute parts may work as well as OEM parts, but then again, some may not.

From everything I've read on the net, it's clear that BMW only supplies this u-seal in conjunction with a new thermostat. That's unfortunate, because the u-seal has a much shorter life than the thermostat. I've never replaced mine, but I suspect that if I open the cover, it would need new seals (o-ring & u-seal) due to age.

Any debris in the cooling system should be resolved as soon as it's detected. Yes, any debris could cause issues for the water/oil pump if not addressed soon enough. For thirty-year-old bricks, I think it's prudent to methodically replace all the seals, gaskets, and other organic parts before they cause an unpleasant surprise.

tgolden wrote:...

Do a Google search for the 225 33099 071 part number. There are several places that sell it perhaps with reasonable shipping charges. There's a guy on eBay that's selling it for $4.95 w/ free shipping.

...

That's the exact one I ended up getting after seeing the crazy shipping prices from epp.

Fri. Feb. 28 - Thu. Mar. 6 is estimated shipping date.  Will advise when it arrives.

diesputnikdie wrote:

tgolden wrote:...

Do a Google search for the 225 33099 071 part number. There are several places that sell it perhaps with reasonable shipping charges. There's a guy on eBay that's selling it for $4.95 w/ free shipping.

...

That's the exact one I ended up getting after seeing the crazy shipping prices from epp.

Fri. Feb. 28 - Thu. Mar. 6 is estimated shipping date.  Will advise when it arrives.

Since it hasn't shipped yet, I would go to a Mercedes dealership or Euro parts store to see if they have one in stock to confirm the fit. I've seen a few different thermostat seals that fit Mercedes applications and they all have different part numbers. It's a big SWAG that this part will fit.

I got this tip on the German flyingbrick forum.

Refill your cooling system with Bel-Ray Moto Chill Racing Coolant undiluted.

http://www.belray.com/bel-ray-moto-chill-racing-coolant

I was told that it prevents trouble for decades.

Regards

If someone would provide an accurate measurement of the inside diameter of the thermostat port and the diameter of the thermostat disc that mounts the u-seal, I think that the USA tech rep for Victor Reinz could provide the correct part number for a u-seal that would fit. Preferably, these measurements should be in mm and measured with a caliper. The thickness of he seal should be specified also.

Gasket:
2.5 mm thick
48 mm O.D.(49.2 when installed)

Thanks duck.

Did you measure he gasket or the gasket socket? Measuring a rubber gasket can be problematic.

Do you have a measurement for the thermostat disc diameter?

I think that when trying to source a rubber gasket, it's good to know the dimensions of the space the gasket fills, because there can be difficulty getting the nominal dimensions on a thin flexible rubber gasket.

Regards

Measuring the gasket wasn't problematic at all. It's 48 mm.

The t-stat is 47.7

Measuring a gasket is problematic in the sense that the measured values sometimes don't match the published nominal dimensions. At least that's been my experience.

So in summary we have:

Thermostat diameter: 47.7mm
Thermostat housing (port) inside diameter:
Thermostat U-seal outer diameter (unmounted): 48mm
Thermostat U-seal inner diameter (unmounted):
Thermostat U-seal outer diameter (mounted): 49.2mm
Thermostat U-seal width (longitudinal):
Thermostat U-seal width (radial):

I'm not sure what direction the 2.5mm thickness indicated.

The mounted diameter of the U-seal likely compresses for a snug fit in the thermostat housing. 

I think that if we can fill in the missing dimensions, it will be easier for the Victor Reinz support to suggest a replacement part number.

Regards

For Canadians, the gasket is Canadian Tire part number 17-4250-2:

robmack wrote:For Canadians, the gasket is Canadian Tire part number 17-4250-2:

It's a ROL Gasket WO8285-001. It comes up as a gasket for a Toyota application. It's likely available south of the Canadian border. However, I don't think it's a exact match for the OEM u-seal. I suspect the OEM is Victor Reinz for the BMW.


It's on Amazon.com as currently unavailable with the following indicated applications: ROL Gaskets WO8285-001 Thermostat Seal Chevrolet NOVA, GEO, 4, 98 (1.6l), 108 (1.8l), 7AFE Engine, 1985-97 Toyota 4, 3E Ser,, 3SGELC, 3YEC, 4AF, 5EFE, 5SFE, 7AFE Engine, 1983-99. I would think that if you went to an auto parts store seeking a thermostat seal for one of the applications above, you would get a very close fit. But, the OP indicated that a Toyota Corolla thermostat gasket was not a good fit.

There's a guy on eBay selling them, ROL WO8285-001 Thermostat Seal, out of Bridgeport, CT for $4.84 w/ free shipping.

It would be nice to see a comparison with the OEM u-seal.

local manufacturer

"tridon" does this

TT2014-180 Thermostat (High Flow)

[url=javascript:__doPostBack('ctl00$cph$fvDetails$lbZoom','')][/url]

CustomName	Thermostat (High Flow)
Features	Opening Temp: 82°C Flange Dia: 48mm Foot Dia: 27.7mm Height: 35mm Bypass style thermostat. High flow version of TT214 series.

as reported by ned  ..fits up just fine  for aussies the whole series of corolla "ae92" also lines up with the models nova and geo in the states ...possibly elsewhere  

the gasket ttg 47 ...looks as though it will fit


looks real close to a perfect fit  (but there are 3 different gaskets for the same series thermostat )
will give it a try tomorrow  and confirm

ok
have got the parts

heres the result
the ttg 47 gasket designed for the corolla at 50mm x 6.5mm is a roundish edge profile rather than a square edge external diameter.
probably to take up the thermostat housing on said corolla .
once fitted over the thermostat is diameter increases slightly (maybe another 1 mm or so )
and whilst you could fight with it and get it in maybe some soap to assist slide it in and down .....
I recon the thickness would be just a little too wide at 6mm resting


I opted for different part

a "ttg 26 " which is actually 47mm external diameter x 4.5mm , but with square edge external 
the sides look like they would compress to straight with the front face of the retaining body assembly
when assembled  a little better

the assembly with the ttg26 gasket fitted to the new thermostat .....(slight issue with the central groove of about .5mm being too wide and the slight stretch to fit around the larger 47mm thermostat )
slid down into the housing quite nicely

because of the slight wonkiness of the central groove care had to be taken in negotiating the ports feeding from the radiator core to the housing

so put that side in first
the rest just slid into place and all looked fine with a good seal achieved

the front assembly went on great with some compression of the thermostat gasket felt as it pushed home easily .
tightening felt good

I will look up the application of the ttg26 to see what it is made- compatible with so that others may benefit and ask for the right thing ....the first time ...

and be assured it fits first time

total time for trying this all out ...about 1/2 an hour

lucky I had a spare radiator handy ..
will apply this to "gerty  later today

as I have had a few issues just recently ...probably haven't bleed the system out  correctly and left air between the reservoir  and filler cap along the breather tube .

testing tomorrow

I have pics ....as soon as I can find the usb cable for the phone (prolly left it at work ....bugga !)

note # the high flow thermostat has about an extra 5 mm diameter on the opening port ..against the original bmw part ....the high flow part looks to me to be about 6 or 7mm wider in diameter than the standard part  you can buy for the Toyota as a replacement non oem part....might make some differences ...but probably not...and maybe not worth the extra $15 purchase price,  but that's just a heads up comment .

Good information. Are you fitting the replacement thermostat seal to the BMW OEM thermostat or to an aftermarket thermostat?

We should rank the fit for these different thermostat seals based on part number.

I think it's possible to find the OEM seal. It's just going to take a bit more effort. I sent an email to Victor Reinz, but haven't received a response. I didn't send any dimensions, only the BMW thermostat part number. I suspect they may want some dimensions if they can't find the specs on the thermostat.

BMW OEM - perfect fit (manufacturer & part no. TBD)
ttg26 - fits when used with Tridon High Flow Thermostat TT2014-180
ttg47 - not a good fit (too large)


Reinz 225 33099 071 - does not fit - too large 60mm diameter

I have a suspicion that there is only a few design differences that cover a hole swath of applications

meaning that there would be only several standard sizes ...
eg
38mm
47mm
55mm
etc

I would think that the real design differences are the fitting ports and retension gadget that are being used .
most are a bell type housing made out of aluminium with more than adequate spare surface area for a good clamp , stength and sealing properties

I guess it becomes quite a different proposition when size  (especially on a motor cycle ) can detract from the overall design - look of the vehicle ....exposed as it is, on our bikes

I think you are correct about standard sizes.

I've check the BMW K-series thermostat part number and the only application is bricks. It may be a non-standard size due to the application.

tgolden wrote:It's a ROL Gasket WO8285-001. ... It would be nice to see a comparison with the OEM u-seal.

As the fog clears from my brain now, I remember that this particular gasket DID NOT fit.  Its diameter when seated on the thermostat was too large for the K100/K75 housing.  It was about three years ago, I abandoned trying to make it work and resorted to finding a used OEM gasket.  Sorry to have mislead.

As for the Reinz 225 33099 071 from Ebay mentioned above, free shipping is offered only to US addresses.  International addresses (including Canada) will cost between $13 and $31 shipping; highway robbery, if you ask me.  I'll be checking Mercedes parts counters or aftermarket suppliers locally for the Reinz part.

As an aside, Ned published in another thread on this forum that the housing O-ring is a commonly available BS134.

Inside (mm)=47,30     Inside (“)=1.7/8"
Outside (mm)=53       Outside (“)=2.1/16"
Section (mm)=2.62     Section (“)=3/32”

If you want to test it I'd be happy to buy one (more?) and stick them in an envelope. This is a limited, time sensitive offer ;-)

duck wrote:http://www.ebay.com/itm/ROL-WO8285-001-Thermostat-Seal-/110667863963?pt=Motors_Car_Truck_Parts_Accessories&hash=item19c451979b&vxp=mtr

robmack indicates in post 47 that it's not a good fit. Perhaps we need a confirmation.

If anyone has bought a gasket that fits or doesn't fit, please indicate the complete maker and part number.

Regards

BMW OEM - perfect fit (manufacturer & part no. TBD)
ttg26 - fits when used with Tridon High Flow Thermostat TT2014-180
ttg47 - not a good fit (too large)
ROL Gasket WO8285-001 - does not fit

Reinz 225 33099 071 - does not fit - too large, 60mm diameter