water temp sensor removal, 300E
 

I can`t get a wrench on this....very tight space. The outer edge of the valve cover is in the way.....is removal of the valve cover the only way to R and R this sensor ?? Many thanks Guys

When I did minbe on 260E 1988 I had to release the valve cover a little bit.
may be thare are thin tools to do it

When I did mine on 260E 1988 I had to release the valve cover a little bit.
may be there are thin tools to do it, but I don't know

If it is one of the temp sensors at the rear, drivers side of the head I don't understand why there is a problem. I use a deep socket, extension and ratchet and change one in less than five minutes. You need to have the new one all ready to go in so that you don't risk losing coolant.

I had a hard time with these too, I ended up loosening the rear engine hoist eye, rotating it down, and using a crow's foot + breaker bar to loosen the sensor, then unscrewed by hand. Make sure the new one is handy to pop in fast.

This one is too fat to get a deep socket over and down to the head.

If your replacing it you can just use a vise-grip and crush the sensor... then hand tighten as best you can should be fine... I did this and it hasn't leaked.

I think the proper tool is a very thin right angled crescent... but this is one of those jobs that makes you question the usually praisworthy Mercedes engineers.

I had to loosen the vavle cover. Simple as that.

From my experience I have learned the following lesson.

If I would have to remove again the cover I would insert a tool on the temp sensor on the back and the temp valve on front before tightening the cover in order to have enough space for the tool in case of later change of sensors.

On my engine, the head gasket was changed for the first time at 200000km (12 years ago!!!) and I believe the mecanics did not take care of that. That is why I had to release the cover.