Just to show what can happen when normal maintenance is not kept up + cheap parts. Car was running very cold even at highway speeds, approaching winter weather I knew I had to turn the heat on soon in the mornings- need the car to be at operating temps. Now it warms up in about 4 minutes of driving. New Behr thermostat fixes this perfectly-

Happy Motoring

Wahler is supposed to be a reputable brand..
But it seems Wahler and Behr has have their share of faulty thermostats brand new out of the box. Which is why you should pot boil test any thermostat with a thermometer before you install them.


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1983 123.133 California
- GreaseCar Veg System

Are we looking at a picture which shows a non alignment caused by the corrosion and letting go of one side's clamp arm ? Can't tell for sure....
If that is the case... then the type of coolant , the ratio to water, and the change interval would be the next questions to examine.....MB says that electrolytic corrosion can occur if the coolant ratio and change interval are not monitored.... you may need to be concerned about the inside of your cabin heater core.... there is a test using an ohm meter to determine if corrosion by electrolytic action is occurring .

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

The pinch weld on one side supporting the thermostat broke, it was a cheap design that relies on thin metal to be held together. The difference in the behr brand is there is no thru-pinch-weld, just supported by the same-side clip. Just thought I would share the differences and failure.

There is little-no corrosion anywhere in the cooling system, I examined it while doing the job. Nice to see a clean system for once!

Wahler is OE near as I can tell so no need to blame the maker without basis. Parts wear out and fail at some point. Most thermostats the world over are made like this, it is a crimped joint not a weld.

Given the amount of corrosion on various parts, I'd say this stat is very old. Metal fatigues from physical movement and eventually cracks. There is a chance that the crimp was not tight enough but this isn't an aerospace quality part. If it was you would be paying many X more.

In the 40 years of being in an around the auto repair business I don't recall this design having an epidemic failure rate and can't recall having one break this way. I did have fatigue failure of a bridge center a few years ago on my 97 C280 but that stat looked to have 161 K miles. See my post 5 1995 e320 running hot