Will Coolant Help This Hot Engine?

Dear Car Talk

Dear Car Talk | Jul 20, 2012

Dear Tom and Ray:

I am a rural mail carrier and have a question about engine coolants. As a mail carrier, I spend a tremendous amount of time on hot asphalt at very slow speeds, and often sitting still. Are there any engine coolants that are capable of making an engine run cooler?

My engine runs a little hotter than I am comfortable with. It doesn't overheat, but it reaches higher temps than it does when traveling down the road at 55 mph. If no such coolant exists, are there any "tricks" that could be applied to get the desired result?

-- Josh

TOM: There's really nothing you can put in there to make it run cooler, Josh -- unless you want to pack the radiator with blocks of dry ice.

RAY: It's more likely that your radiator has seen better days. So the first thing I'd suggest is having your radiator inspected and flow-tested. Make sure it's not corroded and that you're moving plenty of coolant through it.

TOM: You can have someone check your thermostat, too, to make sure it's opening correctly and isn't sticking. A sticky thermostat can make a car run hot in stop-and-go driving. So can a non-functioning cooling fan.

RAY: If all of that stuff checks out OK, your one other option is to install an auxiliary cooling fan.

TOM: Basically, that's an extra electric fan that mounts on the front side of the radiator (your regular cooling fan is on the back side). An auxiliary fan will give you a little extra cooling in stop-and-go driving, which is where you need it.

RAY: But other than that, there's no magic potion, Josh. Except maybe the acid bath they're going to use to clean out your corroded radiator. Good luck.

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