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Discussion Starter #1 (Edited)
This part has undergone an instream revision recently.
It opens @ 79 Deg C as previous.
This "new, revised " unit services other BMW vehicles & Volvo.

I am personally unhappy with the design change & have recorded my
concerns with BMW techinical.
Despite providing dimensional evidence & fitment data in the S38 B36/ B38
that confirms its unsuitability for use in this range of vehicles due
coolant bypass when cold & leakage from the thermostat housing & cover
assemby, the received reply from BMW UK Technical was :

"We sell 56 a year with no problems reported since the change to the original
part number.
We cannot investigate a part because it looks different "

"There is also the possiblility that you will need to replace the housing with a
later version when undertaking the thermostat change."


(That 56 quantity cover the other BMW vehicle variants inc S62 engine that does not remotely
resemble our application)

So we are clear.
The original part is made by Behr Thompson.
It sealing ring is an integrated moulding with the metal thermostat spider.

The "updated revised" part is made "an other".
The sealing ring is not integrated, it is a simple lip seal that does not
seal radially or under compression adequately in our vehicle application.

The sealing ring that the body of the thermostat locates into has not
been changed.
So, that leaves a 0.125mm radially discrepancy between sealing ring & body.

I have fitted this part in its current configuration from an aftermarket supplier
in a quest avoid the massive cost of BMW thermostats.
In two vehicles including my own, both have leaked.
I have also tried other similar units from Gates & Valeo that open @ 79 Deg C
& both have similar dimensional discrepancies despite assurance from the
suppliers that they will work.

Since the above, I have gone back to BMW for these parts due to their
suitability to our vehicle application.

If this is BMW's answer to a valid techinical concern, it certainly mirrors their
general lack of concern for keeping supply of parts available & at sensible cost.

Hope this helps when you buy a stat & find it leaks.
You will end up gunging the cover & housing faces with sealant
which was supposed to metal to metal.
But you won't prevent the internal leak path around the thermostat internally.

Farrell
 

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Is it possible to split the housing/seal and fit the new inner to the old outer - or am I over-simplifying?
 

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Discussion Starter #3 (Edited)
Yes, it is Tony
If you look at the thumbnail attachment, after testing the thermostats side
by side to check opening temp & rate of opening, I started to dissassemble
the new part & use the core components to service the older stat.

However, this takes time & is hardly ideal as the sealing ring may not always be
serviceable but it can work & did so for the Customer who was happy
with my solution.

Cheers
Farrell
 

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Will post another ball ache in a few weeks as new eccentric bolts for the rear trailing arms are NLA. E39 M5 parts can be modified to fit, will post details and pics once mine are mounted and found to be within alignment specs.

Parts situation is bad as far as availability until the cars reach reach MT age, but prices will soar once we do.....

BTW 1.5 y.o. steeringbox is pissing fluid all over the floor through the top shaft seal. No way I'm buying another new one!

Thanks Steve.;)
But...just another ball ache for us all:sad3:
 

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so is it the actual diameter that is different from the OE thermostat? I recently replaced mine, got the parts from my dealer and yes, the s38 and s62 now spec the same thermostat pn (i did both cars), and sealing rings in the housing. I've had no issues with leaks, and my temp gauge is now acting appropriately (previously, it was not warming up properly).

The 'stat that came out of my s38 looked identical to the new one i installed, but i did not make any measurements.
 

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Discussion Starter #8
If stat removed is identical to that installed, you have last of old stk with
encapsulated sealing ring as per my pic showing pictorial difference as well
as many, many dimensional differences.

The install in S62 is no problem as I have replaced water pump & thermostats
in this engine quite recently.
 

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Thanks for the heads up Darren...

Is there a part number change or is the new unit under the same
old number ?
Would be nice to track down an old style one.

I HATE changes like this..:grrrr:

Reminds me of my old days at Rover when nobody paid the bills
and suppliers where changed constantly !
 

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Good work!

(and nice shimming diagram as a tablecloth:thumbsup:. Do we know N236 THO?)

Woo hoo, I'm famous!!!!!!

I am the proud owner of N236 THO. I thought I recognised the photo! Before I saw it, I was going to post it.

when Farrell explained it to me, although I am not overly technical, "A Ball Ache" is a polite way of desribing it.

Cheers

Phill

Edit : @Stevie, what do you mean by MT age?:dunno:
 

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That Farell is such a drama queen :hihi:
 
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Hello Darren,

That is scary and makes me glad I kept my old one that still works OK. I do not understand why an angineering department aproves such a change. I doubt that it has been tested properly.

Such parts issues make for a nice article in Edition Weiss Blau for that matter.

Maybe I should switch to MB that does a whole better job with their 'Classic Centre' :mad:
 

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Discussion Starter #13
Cheers fellas
Hope it helps.
I am very disapointed.

More tales of silliness to follow on another thread on S38 camshafts once I have consulted
with the Customer in question.

Farrell
 

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Just bought a new thermostat

Farrell,
If I'm looking at your pictures I'm pretty sure I've got the newone. Oldone still in the car. Got the same problem as mottati. Engine not getting on required temp.

If I understand correctly from your post. The rubber ring on the old thermostat is different then the newone. The only thing I can see now is that the new ring can flipped off easily from the thermostat.
Do I need to do that and then fit the old ruber ring on to the new housing?
Or should I only use the new thermostat internals (cupper colored including the springs) and put them into the old housing?

Don't want leaking **** of course and I hate to replace something making it worse then before:)

This what realoem says:
<table border="0" cellspacing="0"><tbody><tr><th id="r0">No.</th><th id="r1">Description</th><th id="r0">Supplement </th><th id="r1">Qty</th><th id="r0"> From </th><th id="r1" nowrap="nowrap"> Up To </th><th id="r0" nowrap="nowrap">Part Number </th><th id="r1" nowrap="nowrap">Price</th><th id="r0">Notes</th></tr> <tr><td id="r00">01</td><td id="r01">THERMOSTAT HOUSING</td><td id="r00" class="p1">
</td><td id="r01">1</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">11531315275</td><td id="r01" align="right" nowrap="nowrap">$214.27</td><td id="r00">
</td></tr> <tr><td id="r10">02</td><td id="r11">GASKET RING</td><td id="r10" class="p1">
</td><td id="r11">1</td><td id="r10">
</td><td id="r11">
</td><td id="r10" nowrap="nowrap">11531312287</td><td id="r11" align="right" nowrap="nowrap">$46.87</td><td id="r10">
</td></tr> <tr><td id="r00">03</td><td id="r01">THERMOSTAT</td><td id="r00" class="p1">79CEL</td><td id="r01">1</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">11531315063</td><td id="r01" align="right" nowrap="nowrap">
</td><td id="r00">ENDED</td></tr> <tr><td id="r10">03</td><td id="r11">THERMOSTAT</td><td id="r10" class="p1">79CEL</td><td id="r11">1</td><td id="r10">
</td><td id="r11">
</td><td id="r10" nowrap="nowrap">11537835558</td><td id="r11" align="right" nowrap="nowrap">$130.57</td><td id="r10">
</td></tr> <tr><td id="r00">05</td><td id="r01">HEX BOLT WITH WASHER</td><td id="r00" class="p1">M6X70-Z3</td><td id="r01">5</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">07119912288</td><td id="r01" align="right" nowrap="nowrap">$1.23</td><td id="r00">
</td></tr> <tr><td id="r10">06</td><td id="r11">RADIATOR LINE</td><td id="r10" class="p1">
</td><td id="r11">1</td><td id="r10">
</td><td id="r11">
</td><td id="r10" nowrap="nowrap">11531312626</td><td id="r11" align="right" nowrap="nowrap">$474.30</td><td id="r10">
</td></tr> <tr><td id="r00">08</td><td id="r01">HEX NUT WITH PLATE</td><td id="r00" class="p1">AM6-ZNS</td><td id="r01">1</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">07129900681</td><td id="r01" align="right" nowrap="nowrap">
</td><td id="r00">
</td></tr> <tr><td id="r10">08</td><td id="r11">HEX NUT WITH PLATE</td><td id="r10" class="p1">AM6-8-ZNNIV SI</td><td id="r11">1</td><td id="r10">
</td><td id="r11">
</td><td id="r10" nowrap="nowrap">07129904553</td><td id="r11" align="right" nowrap="nowrap">
</td><td id="r10">
</td></tr> <tr><td id="r00">09</td><td id="r01">SPACER</td><td id="r00" class="p1">
</td><td id="r01">1</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">11531312951</td><td id="r01" align="right" nowrap="nowrap">$9.37</td><td id="r00">
</td></tr> <tr><td id="r10">10</td><td id="r11">ENGINE COOLANT TEMP SENSOR</td><td id="r10" class="p1">2-POL</td><td id="r11">1</td><td id="r10">
</td><td id="r11">
</td><td id="r10" nowrap="nowrap">12621747281</td><td id="r11" align="right" nowrap="nowrap">$41.29</td><td id="r10">
</td></tr> <tr><td id="r00">11</td><td id="r01">GASKET RING</td><td id="r00" class="p1">A14X18-AL</td><td id="r01">1</td><td id="r00">
</td><td id="r01">
</td><td id="r00" nowrap="nowrap">07119963200</td><td id="r01" align="right" nowrap="nowrap">$0.22</td><td id="r00">
</td></tr></tbody></table>

Willem
 

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Discussion Starter #16
Hi
Strip both Thermostats.
Re use old sealing ring & main body.

Use all core components from new unit including :
Stat element.
Both springs (as old units fatigue & cause premature rate of opening.)

Make sure the old sealing ring has no deformation & is clean.

Farrell
 

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though i'm not that sure of what i got, my parts guy said the 'stat was superceeded and is now the same unit for both my s62 and s38. I did get 2 of the same unit, and sealing rings. Went in fine, no leaks, car gets up to temp quickly and runs in the normal range on the gauge.

I will admit i didnt compare the new and old that carefully, looked similar to me, i figured the difference in the seal on the thermostat was new rubber vs 17 year old compressed rubber, making the seal on the oe unit look larger and flatter. At any rate, i've got about a month on mine with no issues, and it is the s62 thermostat.

odd, both of my cars thermostats required replacement at the same time.
 

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Discussion Starter #18 (Edited)
Cool Mike.
I won't fit them in any of my customers cars.
You can't see whats its doing inside the housing.
Dimensionally, the parts do not conform.
The separate sealing ring located inside has not changed to take account
of the stat body & are 0.3mm different so will not seal internally.

Farrell
 

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i don't want to come across as argumentative, i'm my no means well experienced in this stuff!
in my case, they also gave me the s62 sealing ring, (i was essentially given two of the same thermostats and two of the rings), i'm not sure if there is a difference, or if perhaps the rubber is thicker on the s62 ring to compensate for the difference in the 'stat?
 

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Dissemble stat, rebuild old housing with new internals

Farrell et all,

How do I disseble the old stat en reuild the old housing with the new internals?
Dismantleing the big spring is not that difficult but then what? Can't see any bolts or anything like that. To be honest I'm a little worried to replace the old thermostat although I know it has to happen....:1zhelp:
 
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