I've been seeing a little spot of coolant on the driveway and traced it to the T-stat housing where I found the bolt on the bottom to be wet. It's a torx-head bolt so I have to get a socket for it but am wondering if anyone's had any luck just tightening these or is a leak an indication of a bad gasket/o-ring? Either way I need the socket but if I need the gasket too I will pick one up at the dealer before I start. Anyone had a leak at the thermostat housing in the OM 606 or 603 before?

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I had this kind of leak on my OM603 and tightening didn't help. Replacing the thermostat seal did the trick. I replaced the thermostat too while I was at it.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I've used a regular metric socket to unscrew the housing.

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#dieselFLEET
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'97 E300
'99 E300

When checking the EPC I found they have come out with a new housing which I am not sure I have on mine so I ordered one as it was only $20 and also ordered a new T-Stat to boot. So, for about $40 total I will eliminate that darn leak and get a brand new thermostat to boot!

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I tried the seal on mine that didnt work , so I replaced the housing and that solved the problem.

Thanks for the responses. I'm glad now I ordered the new housing. It's amazing that it was only $20...I was prepared to spend at least 2-3X that for that part alone but to get both the housing and t-stat for under $45 seemed quite the deal.

I'm sure the dealer would have charged $300 to repair the leak and simply replace those two parts anyway. I'll take the opportunity to replace the coolant at the same time and I should be all set for another 2-3 years.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

and it wouldn't be a bad idea to use Permatex blue on both sides of the gasket. I've used it for years on all cooling system gasket applications and never a failure...

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2001 E320
1991 350SD 265,000 - SOLD
2000 VW Beetle 1.8Turbo - restored
1997 E320 - SOLD
1988 190E - SOLD
1969 Mustang - SOLD

Finshed the job today changing the coolant, t-stat w/seal and housing, along with a new serpentine belt, low oil level sensor and oil change/filter.

I wouldn't use any sealant on that housing. It's designed for the rubber seal around the t-stat to seal it so I don't think it would be improved by using an extra sealant. If anything the blue stuff might prevent the parts from contacting each other to let the rubber gasket do its job. On mine I could see that the rubber seal had failed at the top and was allowing coolant to escape, probably very slowly as I never ever had to add any to it...just noticed a small spot under the car after it was parked on extra cold nights and traced it back to the housing.

Anyway, it's your car and you can do what you want...mine lasted 9 years the first time with no extra sealant and I'll be happy to get another 9 out of this seal.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Where did you guys get your thermostat housing from? I was resealing mine this weekend in an effort to stop a leak but discovered that rust had eaten the edges of where it connect to the block. I fixed it temporarily, but want to replace the unit ASAP. Fastlane didnt have it.

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1983 300SD White with Grey interior

Dealership...they had to order it but it came in after only a day or two.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Torque spec for this housing on a 97 606 engine??

Bill

I don't like to apply more than around 10 foot pounds when torquing steel bolts into aluminum.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900