Mercedes E320 OM642 Diesel Bluetec / CDI Thermostat REPAIR

This thermostat is in my 2007 E320. I used a 5/32 drill bit to clean it out.

[@arthurschwieger82]

I pulled my thermostat and gave this a try and it worked for now. I got heat for the first time in a few weeks which is nice as it has been below zero for several days. There was a bunch of white stuff in there that I was able to get out with a 5/32 drill bit. Cleaned up the post a little and it seems to be working great. Thank you for posting this.

[@GLPberg]

Good Tip My Engine runs to cool at about 65 Centigrade. Going to try this as well 👍🏼

[@jeffevans3005]

One thing I could add is I have had to repeat this again after 2 years but it was a quick job knowing how to do it and you really don’t loose that much coolant taking it apart as it’s on top of the engine.

[@andrewmccauley2807]

Hi Jeff, I'm going to give this a go. Just wondering what Torque settings you used to retighten the thermostat housing bolts? Thanks Andrew

[@jeffevans3005]

7 foot pounds.

[@tedpirsig154]

How were you able to get the thermostat off and back on to the housing? Mine seems to require a lot of compression, like a special tool would be needed.

[@jeffevans3005]

I used needle nose pliers to push it down and turn.

[@eivydaspiestinis9270]

you are god pal

[@zoomerzoomer-jn7rf]

my e350 cdi runs too cool according to the gauge just 60-75, but the engine is smooth , but i'm not sure if it really is running this cool till i get a diagnostic tool on it, if it that cool do you think my fuel mileage will be affected?

[@kristiandimitrov7762]

My coolant thermostat is shot on my S350 2012 Bluetec engine. A few questions. 1. How hard was it to take the thermostat off as one of the bolts appear to be behind many things. 2. I only ordered the inner part that you've taken out in the video without a new housing as it's 5 times the price if you order the housing too. How hard is it taking out the inner part from the old housing?

[@jeffevans3005]

I didn’t know you could buy the guts of the housing. Where did you find that? It wasn’t a big issue to remove the housing and I think if you had a pair of needle nose vise grips, you just compress the retaining piece of the thermostat and turn to remove. I would still clean the junk that may be in the hole before installing the new thermostat.

[@kristiandimitrov7762]

@@jeffevans3005 Not sure where you are based but in the UK the guts of the thermostat were the first thing that popped up when I googled for it. Ebay, Autodoc you can find the inner parts everywhere. By "clean the junk that may be in the hole before installing the new thermostat" do you mean clean the junk in the housing itself?

[@juian6]

hi how is your thermostat? did it continue to work and keep coolant temps around 87C? Does it stay closed until close to 87C? also what was the stuff u removed? did you perhaps remove the was that is inside it?

[@jeffevans3005]

Thermostat is still working well. The stuff that was making it stick looked like aluminum oxidization, just gritty.

[@mbut123]

I've got a 2012 S350 with a om642 engine with bluetec and stop/start. When warmed up, if stopped at lights it will switch the engine off. Well, it used to quite often, now hardly ever. Looking at the temperature gauge I think it may not be running at hot as it once did. I've a vague memory the temperature would be 85, now it looks like 80, and the scan tool I have reports 75! I've been googling to try and determine the normal operating temperature. It's not clear, but 85 seems an average figure. Whats your normal temperature?

[@bigheadbig5910]

mine is 70 C. Going to change in tomorrow. 9 ltr per 100km on highways is too much.

[@NamNguyen-ij1es]

I think the thermostat rating for this engine is 92 degrees C. So the operating temperature is around 90 degrees C. My engine is same type with your and it does the same thing. Scan tools shown only 70 degrees. Need to change the thermostat soon.