Author Topic: Thermostat Housing 6.9 brocken  (Read 497 times)

Punker

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Thermostat Housing 6.9 brocken
« on: 21 March 2020, 10:14 AM »
Hallo Guys,

As announced, I tried to replace the cooling water and change the thermostat today. The difficulty started with the fact that the two screws on the motor housing could not be loosened, and access to the screws was also very difficult. So I only opened the screw on the radiator. About 15 liters of coolant came out.

The cover of the thermostat housing when I loosened the cover from the thermostat housing I came across a screw that was completely damaged, so I had to use some tricks to loosen the screw. However, when all four screws were removed from the thermostat cover, the cover did not come off. With a little heat and small hammer blows I tried to loosen the lid, which was also not possible. I obviously damaged the thermostat housing on the flange. I then completely dismantled the thermostat housing. You can see the damage in the pictures. The lid of the thermostat housing is glued to the housing, probably in the absence of the thermostat seal (earring). All in all, a pretty bad bankruptcy today.

Now my questions to you:
- is it possible to weld the thermostat housing? It seems to be cast aluminum
- who has any idea where I could get a replacement thermostat housing.

See also the pictures. Yesterday I exchanged the exhaust system (stainless steel) stew and everything went like clockwork. That's what it's like to tinker with classic cars, just like in life, a constant up and down.

Thank you for your support and best regards

Thanks for support and greetings
Björn

1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3

raueda1

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Re: Thermostat Housing 6.9 brocken
« Reply #1 on: 21 March 2020, 10:58 AM »
If it's P/N 100 203 0 274 (top section) and 1002030573 (bottom) you may be in luck.  It's from a USA car but I think it's the same.  PM me.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Punker

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Re: Thermostat Housing 6.9 brocken
« Reply #2 on: 21 March 2020, 01:28 PM »
Hy Dave,

thanks. As I am pretty new here: what means PM me. Sorry.
Björn
1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3

Punker

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Re: Thermostat Housing 6.9 brocken
« Reply #3 on: 21 March 2020, 02:18 PM »
ok clear , Personal Message
Björn
1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3

UTn_boy

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Re: Thermostat Housing 6.9 brocken
« Reply #4 on: 21 March 2020, 02:30 PM »
If the used one from Dave doesn't work out the top thermostat covers are still available new from mercedes for around 70 Euros. It's the same part number Dave mentioned....100-203-02-74.

About a year ago the whole thermostat housing was still available, too, but had a high price of around 300 Euros.....but came with everything, even a new thermostat.  That part number is 100-200-06-15. Maybe you can research that part number is see if someone has a new old stock lying around somewhere. 

PM is an abbreviation for Private Message.  Dave essentially asked you to send him an email through this forum. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

daantjie

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Re: Thermostat Housing 6.9 brocken
« Reply #5 on: 21 March 2020, 02:31 PM »
Bjorn sorry to see this painful experience but indeed it is part of the "fun" ;D
Can you maybe post a pic of the short hose which runs from the housing to the engine?  I think it's 42mm inside diametre.
I have a non spec hose on mine I think but not sure so maybe yours is original to the car still.
Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

UTn_boy

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Re: Thermostat Housing 6.9 brocken
« Reply #6 on: 21 March 2020, 02:41 PM »
Bjorn sorry to see this painful experience but indeed it is part of the "fun" ;D
Can you maybe post a pic of the short hose which runs from the housing to the engine?  I think it's 42mm inside diametre.
I have a non spec hose on mine I think but not sure so maybe yours is original to the car still.
Cheers


This picture may or may not help, but yes, it is a 42mm ID hose.  The picture below shows the part number and the length needed, which is 75mm.  Sadly, you have to buy a whole meter, as that's the only way it is sold.  And it's costly at $40-$50 per meter.  Definitely worth it though.  The hardest part is cutting a 75mm piece straight. It's tough to cut through.  And if you need the two clamps that go around it they're available, too.  Part number 006-997-06-90.  Around $2.00-$3.00 each.  I believe the other end of this hose connects to the intake manifold, not to the engine itself. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

TJ 450

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Re: Thermostat Housing 6.9 brocken
« Reply #7 on: 21 March 2020, 11:26 PM »
Sorry to see this. Many 6.9 / M100 owners will have experienced the same thing as they are very fragile.

In hindsight, the best thing to do would be to remove the whole housing then attempt to remove the cover.

They can be repaired by welding. I would go to a machine shop and ask about having it welded and the surface faced.

Alternatively they are available new as a whole assembly. Not cheap though but a very nice looking part when new.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

daantjie

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Re: Thermostat Housing 6.9 brocken
« Reply #8 on: 22 March 2020, 10:17 AM »
Uhm...well this wasn't in the script...I stand embarrassingly corrected gentlemen, look at what I found when I pulled the thermostat last night, oh boy:

Daniel
1977 450 SEL 6.9 - Astralsilber

UTn_boy

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Re: Thermostat Housing 6.9 brocken
« Reply #9 on: 22 March 2020, 10:44 AM »
Sorry to see this. Many 6.9 / M100 owners will have experienced the same thing as they are very fragile.

In hindsight, the best thing to do would be to remove the whole housing then attempt to remove the cover.

They can be repaired by welding. I would go to a machine shop and ask about having it welded and the surface faced.

Alternatively they are available new as a whole assembly. Not cheap though but a very nice looking part when new.

Tim

As of last year the whole assembly became no longer available. 

Daantjie, I'm glad you found the problem, but It looks like things have snowballed quite badly, haha
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

Punker

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Re: Thermostat Housing 6.9 brocken
« Reply #10 on: 22 March 2020, 10:49 AM »
Hy guys,

thanks a lot for your suggestions, recommendations and support. Things looking much brighter now. In the meantime a German colleagues from a different forum offered a spare housing to a resonable price. See the pictures. I am a bit wondering about the huge temperature sensor as mine is much smaller. But does not matter, the housing is important. Thanks again to all.
Björn

1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3

daantjie

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Re: Thermostat Housing 6.9 brocken
« Reply #11 on: 22 March 2020, 10:49 AM »




Daantjie, I'm glad you found the problem, but It looks like things have snowballed quite badly, haha
[/quote]

I know right ;D holy cow I never thought a thermostat could actually break like that!
Daniel
1977 450 SEL 6.9 - Astralsilber

revilla

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Re: Thermostat Housing 6.9 brocken
« Reply #12 on: 22 March 2020, 12:08 PM »
Uhm...well this wasn't in the script...I stand embarrassingly corrected gentlemen, look at what I found when I pulled the thermostat last night, oh boy:

Hi Daniel,

Wow, Never seen that type of failure mode before!

At least that explains why your engine was taking so long to warm up (thermostat fully open and unable to close).

There’s always a bright side though   : )

Plus, they’re still available at reasonable price. Remember there are several types with different op temp specs. You’re in cold Vancouver I think with cold/long winters, a factor to consider when buy a new one.  One of the experts can detail...
Good luck 
Robert
W116 1977 280SEL & 1979 280SE

TJ 450

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Re: Thermostat Housing 6.9 brocken
« Reply #13 on: 23 March 2020, 12:25 AM »
The part being NLA doesn't surprise me to be honest. What I can say though is that the version for the 6.3 was still available as of the beginning of this year. The only difference is that the hole for the aux fan sensor is not drilled and tapped. It carries a different part number.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

daantjie

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Re: Thermostat Housing 6.9 brocken
« Reply #14 on: 25 March 2020, 04:24 PM »
One good thing about the 42mm ID hose I recently found is that you can buy it from the Classis Centre by the decimeter (10cm) lengths.  I paid $12 net after discount per length.  Not bad if you just need 75mm of it, a good option.
Daniel
1977 450 SEL 6.9 - Astralsilber