M112 Thermostat

[loubapache]

I just drove home a 2003 E320 Wagon 4Matic. I think the thermostat is partially stuck in the open position because the coolant temperature was just a tad below 80 degrees Celsius and the highway mileage was only 23 MPG.

This has happened to my two 300E's and the 97 E320. It seems these thermostats would last somewhere around 60k miles before the spring gets a little fatigued. Immedaitely after replacing the thermostats, the temp would go to 87 degrees and gas mileage improves afterwards.

I took a brief look at the thermostat housing in the car and I have a few questions for those who have done it and the experts. Thank you in advance.

I have dome searches for thermostat but could not find the right answers.

1) The bolts are torx, right? The 1997 E320 thermostat housing use torx bolts that I have done before. However, the ones on the M112 look just a bit different because they appear to have the spiral grooves on them.

2) The new thermostat will come with the housing. It looks all these aluminum parts are corroded together. After I remove the top hose, do I just yank it out? It looks like it takes a big pull, LOL.

3) The engine plastic cover. I tried to remove it by simply pulling it. The left rear corner won't come out. Any trick here?

Just before delivery, the dealer ran the car through a carwash and a few letters of the "4Matic" emblem came off in the cold MI winter. What is the best adhesive remover that will not damage the paint finish.

Thanks,

[lkchris]

re: engine plastic cover: pull harder