Changed my radiator and thermostat and have since been having a cooling issue. When I have the a/c on, the temp gauge reaches between 100 and 120 degrees, about in the middle. What is the temp the car should be running at? It's hotter than heck out and humid here in Miami. When I removed and re-installed the new themostat (Behr), it came with two rubber gaskets. I only used one, the round one with the hole. I couldn't figure out what the other one was for because I didn't have to remove one. Don't know if that has anything to do with it. Also, I have opened the reservoir a couple times and air has been coming out. The last time I opened it, I couldn't hear any air popping out.

When I changed the radiator, I did not flush the block and there are tiny pieces of orange floating in the reservoir. Is there a problem with the thermostat or could it be the water pump? I'm not a mechanic and don't understand how everything interacts. I am planning on having the whole system flushed but am wondering what the issue is.

Where would you recommend I start, if anywhere? I think that is too hot for a motor to be running regularly. I probably shouldn't have replaced the thermostat. If it ain't broken, don't fix it! Thanks, Lance

That does sound too hot, my 300D (with a new radiator stays between 85-95C in 90-100F temperatures with the AC running. It will only reach 100+C if I climb a very long steep hill at highway speeds, then it cools down immediately on the downhill drive.

I don't know what the "tiny pieces of orange" are but it does sound like you need a cooling system flush. You may also have some air trapped in the system. Some times disconnecting the upper radiator hose and filling through there helps. Also, try running the heat for a little while to remove any air from the heater core. It will probably be easier to flush it first, them worry about the air when you refill the system. Don't worry about the "extra" gasket, it's probably for another application. If none of this helps, you can try reinstalling the old thermostat.

run car @ 2000 rpms with defrost heat on high until you see a dramatic reduction in temp reading should just take a few minutes, to bleed air out of system. if it got up around 120 i would be getting cautious. this is per mercedes mechanic who has all the certificates and he said this is what is recommended

i had replaced a bunch of parts and found out it was a bad temp gauge.

__________________
Brian

82 300d turbo 164k - passed on
83 sd - passed on
04 civic hybrid - DD
06 GTO for sale - passed on
84 VW Rabbit Diesel 4dr.- passed on
94 S350D - DD
94 S320 - soon to be DD

Will try the heater and adding through the upper hose. When I removed the old t-stat, it was a bit rusty in there or the water was a bit on the orange/rusty side. Of course, I threw out the old t-stat and garbage was picked up today. I will let you know if those things change the situation. I know some guy suggested that I boil the t-stat first to make sure it functioned properly and I didn't do that. Don't know if that's it or not, but will try this other stuff first and post results. Thanks! Lance

Well, if the coolant looked rusty that's an indication you should flush the system too. I'm assuming you gauge was reading OK before? BTW, did you install an OEM thermostat?

The gauge was reading fine before. And the thermostat was a Behr, exactly like the one I replaced. I just spoke to my neighbor who said it was unnecessary to replace that part. Who knew?

After having been home for about an hour and a half, 2 hours, I opened the reservoir again and more air came out, like opening a soda.

Where is this air going to escape from if I leave the reservoir cap on?

The reservoir is the high point of the system and should be half full of air, when the engine heats up the air should be pressurized up to the pressure rating of the cap. If there is excess air in the system it should eventually find it's way to the reservoir, resulting in a lower level. If the system stays pressurized overnight, you need to start considering a head gasket problem.

SOLVED: I think it really was the arrow issue (Special thanks to Douglas Sherida). I had it pointing east, not north, took it apart again and repositioned and refilled fluid from the upper hose, connected, ran heat until 60C and just drove (incredibly hot out right now in Miami) and it is keeping the temp perfectly!!!!

Thanks again to all of you who helped me resolve this issue! Appreciate it! Isn't the internet great? - Lance

Awesome!

Congratulations Lance.

Wow,
What a story
least it has a happy ending...