Hi everyone,

I've got an '84 300TD that I've done a lot of work on over the last 4 years (the successes of which I largely owe to this forum, so thanks!) Anyway, it's got around 285k on it and is trucking along just fine. Lately though, the operating temp rarely seems to crack 60* celsius and I suspect that the thermostat is stuck open.

A couple years ago, I went through and replaced the radiator, fan clutch and waterpump. I replaced the thermostat at the same time with an 80* celsius Behr that I purchased locally. After following the procedures outlined by various members here for refilling the cooling system without creating air pockets, the car ran at 90-100* celsius whereas before it stayed around 80-85*. I replaced the thermostat with the old one, which returned the temps to their normal 80-85* range.

I understand that there was a problem for a while with new thermostats bumping up operating temps a bit, which brings me to my current situation. Is this still an issue? Are the Behr and Wahler 80* thermostats keeping operating temperatures within the 80-85 range these days, or am I going to end up running closer to 90-95 again? It gets pretty hot here in the summer, and I'm planning to repair the A/C, so I'd like to keep the temps in the range that I (and the car) are used to. Anyone using the 75* thermostat for the W116 V8 powered cars?

Thanks in advance!

Search for my post on this. My 1984 300D was running at 60 C. The thermostat appeared OK on cursory look, but more careful data showed not. With a new T-stat, runs at 82 C (as my 1985). I gave PN's, plus checked the temp sensor.

Found it, thanks Bill! I'll grab a Wahler.