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Q: Unusal high coolant temperature on 2003 Chevrolet Express 3500

Enthusiast 01be16a5a93688912f14755221fb15211b518d9a788cf01b455e03cc1bd585ac
In a hot summer day the coolant temperature is above normal over 210F even running on highways, it will not drop to mid range. You could feel the transmission slowly giving up because it is so hot and slips. Mechanic changed the themostat but still the same. Why?

Engine temperature is controlled in a few places - most notably - how is the fan working for you? Does it blow at all at a high speed when the temperature of the engine is high?

Also, make sure after the thermostat was installed that all the air was bled out of the cooling system.

You could have a radiator flow issue. You could have a water pump circulation issue. You could have a base engine problem at the cylinder heads.

So - some testing is in order to figure out what's going on. Good luck,
Thank for your reply. This van had only one cooling fan and is driven by the engine. I did suspect a bad fan clutch but the mechanic said it was fine. The other three issues you mentioned was not tested. Because it is a working van, I dont want to leave it at the garage for hours to get it tested. I was hoping someone had a simple or direct solution to this problem. But for your info the van works pretty fine when temperature was cooler. Houston has been hitting triple digits everyday this summer, and the problem evolved. I might think of adding an aftermarket electric cooling fan to redeme the situation if the mechanic dont find a problem to it.
Your fan clutch may indeed be a problem. Do you have more of a problem around town or on at highway speeds?
It stays hot at noon time and never really wants to drop, driving around at traffic lights makes it worse sometimes
Just trying to narrow down the symptom. If it's around town, your engine depends on the fan a whole lot more. Check out the fan clutch for real - you can do it yourself by making sure it's both not stiff to turn nor spinning freely with the engine off. Either way would be a negative.
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