cooling question
 

I have a new radiator (nissens), a fairly new thermostat from my mb dealership and a new cap. I have been running a little warm at stoplights, warmer than I am used to with my behr rad. I have noticed that the metal piece that the cap attaches to on the expansion tank is loose and seems to be leaking gradually. Is this what is causing the higher temps. It seems to be getting just above 100 degrees Celsius. When I am driving the engine temp is normal just above the 80 degree mark..

Thanks,

Check the viscous fan clutch.

review the entire system for proper:

>aux fan operation: incl fuses and relays, cut in's are according to spec
>cap should secure snug on the overflow tank
>ensure MB coolant and proper mix is used
>ensure all hoses are no leaking and in good order
>pressure test system
>ensure belts/tensioning are healthy and operating properly
>already mentioned: fan clutch
>review H20 pump condition
>ensure that the entire rad mounting and gen area is free of accumulated debris and dirt
>etc.

this is a good start- good luck and let us know what turns out
-fad

good news.....when I went to refill the tank it appeared that the aftermarket cap (stant) was not seated properly. After refill and proper cap replacement every thing is cool :cool: :D Sitting at the drivethru just a little while ago with the a/c on the temp was steady reading about 87 degrees celsius. Thanks for the help guys

You said the metal piece on the exp. tank that the cap attaches to is loose. If it's still loose, you're system will lose pressure. Been there. Not sure how the cap resolved the loose neck on the exp. tank?

Once I had my coolant changed on my S420 at dealer. My car used to hit 100 but after a couple of months, the temp has now settled to 80C. My best reasoning is 1. air bubbles 2. coolant not homogeniously mixed completely 3. too much coolant. 4. Additives in coolant.

Sometimes, engine overheating has nothing to do w/ the cooling system but the oil pump. Oil is also recirculating throughout your engine causing cooling. If the pump is bad, the engine will heat up.