diesel engine thermostats

[p100]

I have tried 2 brand new brand name 80 degree C rated thermostats in my '83 300DT. The car consistently runs at 95 degrees C. Even after I put in a new temperature sending unit. The original thermostat that the car came with when I bought it a few months back, makes the car run at 80-85 degrees. I replaced it only because it evidently was sticking open a bit as it took a long time for the car to warm up. Now I put it back in the car. It runs steady at 80 degrees and never goes beyond 85. The only penalty is that the car takes much longer to warm up.

I replaced the thermostat in my 300SD about three years ago. The car steadily runs at 85 degrees C and warms up pretty quick.

What I have concluded is that at some point all these new 80 degree rated thermostats have been calibrated to actually open at about 90 degrees C. For what reason I have no idea - maybe hotter running diesel has less harmful emissions? At any rate, I really believe that there is nothing wrong with my car or its cooling system, except I cannot find a new 80 degree thermostat! because they evidently do not make them anymore, despite stamping 80 degrees on them.

I hear similar complaints from other people. In fact, there is a long article on the same subject on dieselgiant.com Has anybody put one of these new thermostats in water to see at what temperature it opens? If anybody knows of any new thermostat that actually opens at 80 degrees that fits these cars, let me know. I am getting really tired of this. Now I have a brand new radiator sitting in a box, which will evidently do nothing, because it will run again at 95 degrees with one of these stupid new thermostats!

[79Mercy]

I guess this is a 80C t-stat: Your Parts Search Returned 1 Part(s)

[108Benz]

I have read somewhere here on these forums that the 80 C t-stats are made to open up at 87 C so you are close with your 90 C est.

[p100]

Originally Posted by 79Mercy

I guess this is a 80C t-stat: Your Parts Search Returned 1 Part(s)

Thanks, but I already tried theirs and it is NOT an 80 degree thermostat!

[79Mercy]

What about this one: Sunvalley New Mercedes Parts

[p100]

Originally Posted by 79Mercy

What about this one: Sunvalley New Mercedes Parts

Thanks. I may have to buy something else too because shipping is $ 10.70, almost as much as the T stat itself!

[79Mercy]

I bought one from these people a while back and it is a 80C t-stat.

[p100]

Originally Posted by 79Mercy

I bought one from these people a while back and it is a 80C t-stat.

That's just it. A while back (about 3 years ago) I bought one for my other car and it too was an 80 degree one. So they must have modified these recently to open at higher temperature. Is this annoying, or what! I never realized that a thermostat could be such a pain in the neck!

[79Mercy]

where did you buy the one for your other car?

[p100]

Originally Posted by 79Mercy

where did you buy the one for your other car?

I got it from thebenzbin.com. I do not remember what brand it was , I believe it was either a Behr or a Wahler.