Again. Thermostat help

[milarsky]

Happy New Year all.

I still cannot procure the proper thermostat for my M5. even Bluntech cannot answer what the problem is. I can say for sure that each of the thermostats I ordered and received from Pelican, Autohauz, FCP, were all incorrect. Can anyone shed some light on this complicated, vet seemingly simple answer?

best,
Jeff

[austin8753]

the aftermarket catalogues all list the incorrect thermostats. ask me how i know. bite the bullet and get one from the dealer; it's the only way i was able to get the correct unit.

[milarsky]

Thanks Austin! It seems like all dealers list it as back ordered with no ETA.

thanks,
jeff

[john r.]

Just looked at one of my old parts books.
Shows part number 11 53 1 307 737 for thermostat.
Just checked the dealer on the thermostat number.
This is today 01/05/21
Dealer said 1 in stock in my facing warehouse (Stockton, CA).
I'm in Northern CA.
They also said a couple more thermostats in other warehouses around the country.
Makes me think of my old M5 checking these numbers.
Hope this helps. When we used to stock these thermostats I remember we always had to get from BMW, every other euro brand was incorrect.
John R.

[austin8753]

Just looked at one of my old parts books.
Shows part number 11 53 1 307 737 for thermostat.
Just checked the dealer on the thermostat number.
This is today 01/05/21
Dealer said 1 in stock in my facing warehouse (Stockton, CA).
I'm in Northern CA.
They also said a couple more thermostats in other warehouses around the country.
Makes me think of my old M5 checking these numbers.
Hope this helps. When we used to stock these thermostats I remember we always had to get from BMW, every other euro brand was incorrect.
John R.

that's the correct part number. my local OE warehouse supplier seems to think the M30 thermostat interchanges ("TH1528.80J"), but no matter how many times i call and inform them "NO, IT DOES NOT", they refuse to take it out of the catalogue...

Jeff, i'd advise calling your local dealer. when i bought mine in May, 2019, there were quite a few in Stockton (as John mentioned above), so i wouldn't be surprised if there were still some there.

best of luck. make sure to order the o-ring for the overflow/recirculation valve, as well (upper most part of the thermostat housing cap)

A

[john r.]

If I remember correctly, the M5 thermostat from the dealer did not come with the o-ring.
Original number for thermostat o-ring was 11 53 1 304 202.
Dealer says that number is NLA; superseded number they say is 07 11 9 906 322, in BMW warehouses.

As Austin wrote, you'll also need the small o-ring.
part number 07 11 9 906 328.
Good luck. John

[milarsky]

Today, 1/6/21: Called Stockton CA BMW, and he said specifically there are NONE in the USA. BMW has 44 of them on backorder, and not listed as NLA.

Thoughts?

best,
Jeff

[austin8753]

i also called my local dealer this morning - nothing :/

maybe you will get lucky and find somebody who happens to have one on a shelf, somewhere...

[S62ninja]

Schmiedmann is backordered until mid February, this may have something to do with Covid. I've been searching for a few months too and went with a NOS off ebay...don't think it's working correctly though.

[cgraff]

Given the current BMW OE part number is on back order You have two options.

1. Get the M1 part, which cross references to the early M30. I forgot the exact PN, but I ordered one and it fits. The difference between it and the M88/3 and S38 is the diameter of the block off plate side (35mm vs 30mm). This means the flow around it when the tstat is open is slightly more constrained, meaning faster warm up time.

2. Source a alternative manufacturer that cross references to the Behr/BMW part. I did some PN research and actually found the original Behr part number (NLA), not the current one that is incorrect and actually bought a Verdet (will confirm later) that cross references. The problem with this one is that I think the block off plate starting position (when open) is too far out (ie too “closed”).

Personally I’d go with option 1 if you’re in a pinch. Then wait until the backorder comes through.

-Chris

[milarsky]

Thanks all! Great responses. I ordered two from Schmiedmann and will report back as soon as they arrive.

best,
Jeff

[cgraff]

Summary of issue:

BMW has three types of thermostats from a physical dimension point of view:
1. Early M30 (also used on E26 M1); PN ending in 251 041 or 254 065.
2. Late M30; PN ending in 953
3. M88/S38; PN ending in 737

The late M30 style thermostat does not physically fit in the M88/S38. The Early M30 style can fit M88/S38, but it is not ideal b/c of the diameter difference of the block off plate.

Block off plate of the early M30 is 35mm vs. 30mm of the M88/S38.

Now Mahle has cross referenced a TX27 for the late M30 (which is correct). But they cross reference a TX21 for the M88/S38 which *does not match the dimensional requirements*.

Mahle catalog for TX21:
https://catalog.mahle-aftermarket.com/n ... 74#divider
You'll see TX27 is close:
https://catalog.mahle-aftermarket.com/n ... 85#divider

The early style M30 cross references to a Wahler 4231.80.
Here's a catalog pic and dimensions:
https://www.auto-doc.fr/wahler/1719119

You'll see the big difference in the location and shape of the outer flange relative to the block off plate.
However, the block off plate may actually be 35mm diameter (I ordered one and measured it as such), vs what's shown as 30mm diameter.

It is possible again to use the 4231.80 in the M88/S38 (and if you get the block off at 30mm diameter, it's ideal). It is also possible to use the early M30 (ending in 041/065) in a M88/S38 (it was used in the M1). But not ideal.

So there is NO MAHLE part that fits the S38/M88.

-Chris

P.S. I have cross referenced the dimensions above against internal drawings.

P.P.S. Schmiedmann has contacted me on 2/9 with the lack of OE, and offer on Mahle. I told them exactly the issue above.

[austin8753]

Summary of issue:

BMW has three types of thermostats from a physical dimension point of view:
1. Early M30 (also used on E26 M1); PN ending in 251 041 or 254 065.
2. Late M30; PN ending in 953
3. M88/S38; PN ending in 737

The late M30 style thermostat does not physically fit in the M88/S38. The Early M30 style can fit M88/S38, but it is not ideal b/c of the diameter difference of the block off plate.

Block off plate of the early M30 is 35mm vs. 30mm of the M88/S38.

Now Mahle has cross referenced a TX27 for the late M30 (which is correct). But they cross reference a TX21 for the M88/S38 which *does not match the dimensional requirements*.

Mahle catalog for TX21:
https://catalog.mahle-aftermarket.com/n ... 74#divider
You'll see TX27 is close:
https://catalog.mahle-aftermarket.com/n ... 85#divider

The early style M30 cross references to a Wahler 4231.80.
Here's a catalog pic and dimensions:
https://www.auto-doc.fr/wahler/1719119

You'll see the big difference in the location and shape of the outer flange relative to the block off plate.
However, the block off plate may actually be 35mm diameter (I ordered one and measured it as such), vs what's shown as 30mm diameter.

It is possible again to use the 4231.80 in the M88/S38 (and if you get the block off at 30mm diameter, it's ideal). It is also possible to use the early M30 (ending in 041/065) in a M88/S38 (it was used in the M1). But not ideal.

So there is NO MAHLE part that fits the S38/M88.

-Chris

P.S. I have cross referenced the dimensions above against internal drawings.

P.P.S. Schmiedmann has contacted me on 2/9 with the lack of OE, and offer on Mahle. I told them exactly the issue above.

very good information here - thanks!

[Ken H.]

So what's the next step, Chris?
I tend to suspect this is a manufacturing issue @ Wahler; from their and BMW's view, the demand simply isn't large enough to justify setting up the tooling.

FWIW, I am running a -065 t-stat in Lucifer's Hammer (4-liter S38). Have been for several years; Paul B. used this p/n as part of the build. It has functioned with, apparently, no operating issues. Not sure if the installed unit is Mahle or Wahler.

Out of an abundance of caution, have been trying to locate a -737 part. No Joy. I've had one on b/o @ Schmiedmann since before there was dirt. Ditto ECS. They tell me the part is coming, but keep sending me emails pushing the ship date out. Started with an order in early December; we are now being told about sometime in mid-Feb. Believe it when I see it.

Tim at Autohausaz advised me that the TX21 Meyle unit is cross-referenced to the -737. While Autohausaz's website shows this cross-reference, we know this isn't the case. So we are at square zero as far as "source information" is concerned.

[cgraff]

Until BMW decides to find a supplier to manufacture another batch of the -737, there is no OE or OEM available t-stat that matches the dimensions of the -737 exactly.

Of course when BMW gets a batch manufactured, it will jack up the price 3x, per the usual.

In the meantime, you have two choices:

1. you can use the OE BMW "early M30" part (065), which the only consideration may be a slightly faster warm up time due to the 35mm diameter vs. 30mm dimension on block off plate. Functionally the temp is still the same 80 deg C. And again, same part as used on the E26 M1.

2. You can find a Wahler 4231.XX which is dimensionally the same as above. I believe Wahler has the standard 4231.80 which is 80deg C. They may also have other temp options.

-Chris

[bigwave]

Thanks Chris, those at least sound like some options. Schmeidmann just got back to me today on the backorder, they are suggesting the Mahle part. There is one letter difference at the end of the part#, but it's still a TX 21, which I'm guessing will not work. May just replace hoses for now without opening the t-stat housing. Here is what they sent me:

"Unfortunately the original thermostat are in backorder with no delivery date.
Can you please let me know what is the issue with other brands?
I have found an alternative on the same number from MAHLE that we are able to get. TX 21 80D that is a replacement on the 11531307737 number."

[cgraff]

@bigwave

Yes, that's what Schmeidmann emailed me as well this morning 2/9/21. They are getting info from Mahle, which is incorrect.

I for one actually ordered the TX21 last year from Pelican (based on the Mahle xref), and when I did my service I obviously found it didn't fit when I opened everything up. Luckily Pelican accepted the return. But I had to put in the original back in.

I then started cross referencing the dimensions.

In meantime I checked my parts stash and was lucky to find a OE -737 I must have bought a decade ago when I had my other M5. So I have a replacement in hand myself. But I also ordered a -065 to have just in case and to compare side by side. I have personally physically compared them and dimensionally they are same, except for that block off plate diameter.

-Chris

[cgraff]

I was in touch with Schmiedmann, who seems to have identified an alternative supplier.

They found (and will likely sell you) the following:

VEMO/VAICO V20-99-1256

Based on the photos Schmiedmann sent of the actual part and the dimensions from VEMO, it ought to fit perfectly for S38/M88 series motors.

Here's the contact info at Schmiedmann:

Chris Lykkegaard
SCHMIEDMANN ODENSE A/S
Herluf Trolles Vej 15
5220 Odense SØ
Tlf. +45 65 94 15 45
E-Mail chris.l@schmiedmann.com
Web www.schmiedmann.dk



-Chris

[bigwave]

Arrived yesterday, though car is in storage for another month before I can try to see if it fits. Just figured I would share what comes in the box as different suppliers tend to leave some gaskets out. Fingers crossed that it fits.

[milarsky]

I received mine, the same as above. I do not think this is the correct part, unfortunately.

[bigwave]

I received mine, the same as above. I do not think this is the correct part, unfortunately

Just curious, any thoughts on why you think it isn't correct? I'm asking since Schmeidmann has an 8 day time limit on their return policy and I can't try it on the car for at least a couple weeks. According to Chris L. from Schmeidmann the measurements match the NLA part exactly. He had investigated deeper after receiving messages from many of us that the cross refrenced Mahle part isn't correct.

[e24mpwr]

Howdy folks - I recently went through this ordeal with my M635 and my shop (West German Garage) found this, and said it was an exact visual match:


It's only been a couple weeks, but the new t-stat is working great! Only $20 or so, too.

[milarsky]

Sorry folks, it is NOT an exact match. The M5 thermostat is not available, no matter what vendors tell you it is correct. Not available from BMW, manufacturers, or vendors.

[e24mpwr]

Sorry folks, it is NOT an exact match. The M5 thermostat is not available, no matter what vendors tell you it is correct. Not available from BMW, manufacturers, or vendors.

My shop initially ran into the substitution issue, so he was looking for the physical match, and said he compared the Vernet to the original (Wahler - "Made in W. Germany") before installing.

My M635 has been running great with it installed for the last couple weeks...

Is M88 different than S38? (my understanding is they're the same across E24 M6/M635 and E28 M5)

[e24mpwr]

As an update/follow-up, I've accumulated quite a collection of thermostats!

Despite the differences in some dimensions, I believe all of these would work (they're all listed as compatible with M5/M6):




The Vernet is what is running in my M635 and the cooling system is functioning perfectly so far, including a group-drive that involved a bit of spirited driving as well as more than one very-slow "sitting there" situation as we were parking at stop-offs/etc.

My calipers are cheap ones, and don't have quite the depth or span to get good measurements of the outer diameter of the big plate or the height of the spring assembly, so I don't want to pass those along, though it appears that the "height" from the mounting plate to the bottom plate is taller by approximately 1.4mm of the BMW part for the QH and Vernet parts (they're very close). I can't speak to the impact of that, though the Vernet is working perfectly as far as I can tell in my car. The Vernet has the identical diameter bottom plate of the original that come out of my car.