back from the shop
 

Well, my 1990 300e that had blown a headgasket with 215000 miles on it just came back from the shop. We were going to sell her but decided to hold on to it a while longer(I hope). The job included reworking the head, new timing chain and tensioner, new thermostat, waterpump and radiator. The question is it seems to run a little warm. My wife drove it home with the a/c on open highway and the temp was on the bar bt. 80 and 120, I would think, logically that would be around 100 degrees. Is that correct? I have read posts that indicate the temp should be around 90. Should I be concerned?

If I'm not mistaken, your MB has the single cam 103 motor.

Mine runs just over 80 on the highway in a very warm climate with a/oc on.

If you are running over 90 on the highway(a/c or not), I would start looking for the reason why. Could be things unrelated to the head work..ie..t-stat/old radiator/debris on condensor/radiator/etc.

The real question here is interpreting the analogue gauge on the dash. Does the bar bt. 80 and 120 represent 100? It would seem to be logical that it would, only thing is that the bar on the gauge is not exactly half way bt. 80 and 100.

I have always assumed that it represented 100dC and if yours is running there I would start nosing around. See what the temp rating of the thermostat that they installed is.

Okay, after reading through many more threads I found one that indicated that the third tick would indicate 100 degrees. Can any one confirm this? The same thread said that the temp with air on should be around 95 degrees and w/o the air on it shouild be around 87 degrees, any confirmation on that?
Looks like I should have gone ahead and done the fan clutch too while everytng was off the engine! Have not had a chance to test it yet but it probably woud have been a good thing to do as a p.m. measure. Daarn I hate to learn this way!!

If the fan clutch is bad the temp will rise when it is sitting at a red light or idling for a period of time. Elevated temp while going down the road at 50 mph + is something else.

Had the same problem after I changed my waterpump. About a week later, things went back to normal.

the above
 

post may have had air trapped in the system.

do check the stat temp rating. there are different ones out there, but prob none rated for 100 deg. actually could be though, my dodge runs at 190. that is close enough to read as 100 on your stat.

tom w