farrell

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

Attached Thumbnails

 

Mmm-Five

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

__________________
"If you're not producing skidmarks you're not trying hard enough"

2006 e86 Z4MC (überkart)
1990 e34 536i (ex-überbarge-zwei)
1994 e34 538i (ex-überbarge-eins)
http://mmm-five.net/

farrell

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

Stevie

Good work!

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

farrell

Thanks Steve.
But...just another ball ache for us all

Yes, table cloth is a little alternative.
Owner is a member here.

Stevie

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!

mottati

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.

__________________
Mike

91 M5 Alpine White II, Silver Gray 3/90 production
17x8/17x9 M system with PS2, 20mm touring roll bar; Ground Control Coilovers; EAT Chip, CD43; bmw/nardi blackline steering wheel, 3.8 Cam Gears

08 535i / 6 speed
Space Gray; Gray; Sport/Premium/Nav

00 M5 Ti Silver; Imola/black sportiv --Sold
Engine:
Supersprint Headers, Dinan CAI kit and MAFS, Throttle Bodies, Cams, Ported heads, Exhaust, Custom dinan software, Evosport Pullies, Dinan clutch and lightened flywheel; Ignition solutions plasma coils
Suspension:
Dinan Stage 3 with front and rear Strut Tower Braces, Beastpower Sway bar brackets, Dinan Wheels with 275/285 PilotSport, X5 Thrust arm bushings, Stoptech 355mm 4 piston front, 355mm 2 piston rear brake kit, Dinan 3.45 diff
Interior/Misc:
Eurodash, updated steering wheel, Bluetooth retrofit, Sirius Retrofit, hardwired V1, Widescreen Mk4 nav, M audio retrofit, Ice Link, BSW Stage 1 speaker upgrade, bmw towbar

farrell

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.

Alan Archer

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..

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

__________________
///M5 the only substitute for capacity is even greater capacity...

Teamsreth

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?

__________________
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Phill C

Its not quite what I was looking for......
Its what I have always wanted!!!