How do I remove the Thermostat from the lower housing? I removed the 3 bolts and the top half of the housing. I pulled up hard on the thermostat with pliers, but it will not move.

I am afraid that I will damage something pulling so hard. I bought a new MB t-stat and o-ring. I in the middle of flushing the coolant and thought I would change the t-stat at this time.

Pleeeese help!

I do not know your model, but will offer this as your description sounds similar to my arrangement.

You removed 3 bolts and lifted off the upper housing cover. You're likely having a tough time pulling out the thermostat because of the thermostat gasket that runs around the circumference of the inner part of the lower housing. This gasket must first be removed. I use a sharply pointed object to gently dig it out. Once removed, the thermostat pulls out easily.

i had a similar problem on my 190e car.
the thermostat was stuck solid and could not shift it-but as i was replacing it as a preventative measure, and it was not particularly faulty-i left it alone-.now when i next tackle this job, iwill remove the gasket(o ring) as per mike's advice.
johne,do keep us posted of the final outcome

Mike, thanks for the advise.

I will dig the old gasket out as you suggest.

Question: Does the new gasket go in the lower housing first? or does the T-stat go in 1st with the gasket on top of it?

My guess is the gasket goes first then the t-stat when re-assembling.

Oh, the vehicle is an 1994 E320.

The gasket is slotted in the middle and suspends the thermo..

That's why you have to dig it out and use the new gasket...
A little wd helps on the new one...

Just replaced the t-stat. Thanks for the help!

Observations:
After you cut up the old o-ring, you can pull up on the t-stat to remove it. Use an exacto knife to cut across the O-ring.
Make sure the little bee bee hole is nearest the firewall.
The t-stat goes in the housing first then the O Ring goes on top of the t-stat.
Clean bolts threads with wire brush, they have a little build up on them.
Torque 3 bolts to 9NM or 7 ft lbs.