Hey guys and gals,

​​​​​I have been dealing with a overheating issue that had my indi stumped for a while that id like to with you in case you encounter the same issue, as our cars age we are now seeing new failure types that create a big dent in your pocket. I do a lot of stuff on my car my self but when I don't have time I take it to a great garage in Bakersfield California, European Performance Automotive, Mark the owner is a great mechanic and very knowledgeable about most German imports especially Mercedes which he trained on for many yrs. Any way I digress the issue I was experiencing was the vehicle would over heat, the first thing checked was the head all good there, then water pump, blower fan all seamed good and working at low speed driving. MArk found one of the two speed blower fan relays wasn't always coming on, not a big issue or repair cost $17 or so but the car still would over heat. So I had him put my spare radiator in the vehicle but still no changes to this frustrating over heating issue. Mark checks the car under load and monitoring the coolant pressurization and finds the coolant expansion tank cap was failing when the vehicle was under load for a while. He replaced the coolant cap and all is fixed now. Had I of taken my vehicle anywhere else it would have cost a fortune in diagnosis charges and repair. He didn't charge me for finally narrowing the issue down and fixing it. I really appreciate his dedication and fantastic customer service, will be taking my car back for a lot more work doing in the new year, new suspension control arms/bushes, wheel bearing all round and dropping the ride hight with my new springs and then my last project install a killer chiller. It gets really hot in the summer in the valley and we all know about heat soak issues with our cars so this will help a lot.

Cheers all.

christmas blessing and wishing you all a better new year than the past one.

 

Glad you figured out the issue. I replaced the tank cap on mine recently as it was leaking/seeping slightly. Thankfully it never over heated.

 

be sure you bleed your coolant system and get the air bubbles out of the circuit...for months i had high IAT's even with upgraded PLM heat exchanger and Speedriven intercooler only to realize that i had air bubbles in the line since it wasnt bled properly when those were installed. once bled out properly my IATs were dropped and were consistent at about 25-30 deg Farenheit above ambient even with repeated hard acceleration.

check this out from other member post:

https://mbworld.org/forums/c32-amg-c...ed-system.html