Thermostat going bad?

[190D22]

My engine temperature has been at 100C lately, and it usually is around 85-90 range. I do city driving mostly. Even when I turn the heat on all the way it really doesn't come down too much from 100. Is it just the weather or what? I have a brand new radiator, fresh coolant, and a new aux coolant pump. Is this nothing to worry about?? Thanks in advance.

[engatwork]

Go to one of the discount auto parts dealers and purchase one of those devices that will tell you the %age of coolant/water. What kind of condition is your thermostat and water pump in?

[190D22]

The water pumps are fine. I don't know if the thermostat is working, that's why I asked. Mercedes put my coolant in so I am sure it is the correct mixture. Since the thermostat is only 12 bucks I think I will get one. How hard is it to install? Thanks.

[Jim Anderson]

The hardest thing is you have to partially drain the radiator. Mine started doing that and I just went ahead and changed the thermostat and it looked like my temp gage broke, like it got stuck at 82 deg, before it had moved around. I guess my old one was getting old and the new one acted very different.

[190D22]

I was hoping I didn't have to drain the coolant... Well I guess I will though. Any special tips on doing a thermostat replacement? Hard or easy to do? By the way, how do I get it so my electric fan and my belt driven fan come on at once? I've heard of people doing this to keep their engine much cooler. Thanks for the replies so far!

[190D22]

Oh yeah you saying the gauge was bad reminds me... My temp gauge flops around on occaision as does my fuel needle. I looked down at the temp gauge and it was bouncing around, and I was at a red light. The fuel gauge doesn't bother me, just as long as it's approximate. Does anyone else have this going on as well? Diagnosis? Solutions? Comments? Any input greatly appreciated, thanks!

[190D22]

Anyone? I'd like to know what's up with the temp going up to 100 all of the sudden.