While in the shop this week, my mechanic saw a small leak from the plastic thermostat cover. Went to my local parts store to get the replacement. They gave me a metal (aluminum?) one with a hole on top perhaps for a sensor. When I said the plastic one didn't have a hole on top, they gave me a plug bolt to insert. They didn't have the copper crush washer bot will have one for me on Monday.

Is this the correct thermostat cover? Was the replacement for the plastic made as a one-size-fits-all? I don't believe having a plugged hole will cause any problems.

--Craig

Yes, that is the correct and improved cover.

The plastic cover breaks (good MB engineering) and the Aluminum one will not break.

The hole on the top is a breeder hole when you fill coolant.

Thanks Bo,

I am going to replace the weeping plastic cover today.

--Craig

I replaced the covers on both of my 300Es when the improved one came out. I think they were like $15 each.

With the sealed plastic cover, I had to remove one of the breeder nuts on top of the engine when filling coolant through the expansion tank. Now with the metal cover, I just loosen the nut on top of the cover and fill coolant through the expansion tank.

If I park next to a 450SL what would I get?
--Craig

Craig:

You then get a SLK450 AMG by parking next to a 450SL through breeding.

Sorry, bleeder hole.

I jacked up the front end so I wouldn't lose too much coolant and removed the plastic cover. While I was replacing the cover, I went ahead and replaced the thermostat too. The bleeder hole came in handy when refilling. What will these engineers think of next?

Figure I'll hang on to old one as an emergency spare.

Now I'll have to cruise down to Newport Beach to see if I can find a sexy, new MB to try out the breeder hole.

--Craig