Blazer 97, overheating at idle.

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Ensenada, Mexico
Hi.

Lately I've been having issues with the temps in my blazer. A couple of weeks ago I changed the thermostat, antifreeze, and radiator cap with almost no improvement.

The temp rises quick to 210F and it stays there, until I get in stop and go traffic. Then it goes up to 235-240. Once I get to speed maybe it goes down to 220, but it never gets down to 210F.

Fan clutch seems to engage ok, but with the engine off and cold feels very stiff.

For replacement I can get a torflo severe duty (Autozone), and normal Napa one (seems to be made by Dorman).
Which one would be better?

Oh! And to top this overheating problem, I live in a very hot place. On average we get 110F in the shade, and has gone up to 120F. In direct sunlight it can get to 140F, so take that in consideration for your recomendation.

Thanks!
 
Be sure to clean out the radiator fins along with the A/C condensor fins as well. Its amazing how those can clog up and not let enough air flow to cool the coolant down. If that fails, after you replaced the thermostat, coolant and the radiator cap ( don't forget the cap. It holds pressure which allows the coolant to not boil at high temps.), then you will have to look into a head gasket problem.
 
I just had the coolant flush, thermostat (195F as spec'd) and cap (16 PSI) changed. No improvement.

There is no coolant loss, and the oil looks clean with no signs of contamination. Except by a small rear main seal oil leak, engine is strong and without issues.
 
Did you check the temp with a thermometer? You may have a bad gauge.

Quote:
Fan clutch seems to engage ok, but with the engine off and cold feels very stiff.


How does it feel hot? Is this a thermal clutch or centrifugal force?
 
Last edited:
Originally Posted By: Trav
Did you check the temp with a thermometer? You may have a bad gauge.


Good point. But until a couple of months (when temps were in the 90F range), the gauge showed a
Originally Posted By: Trav

How does it feel hot? Is this a thermal clutch or centrifugal force?


It's a thermal clutch. Still stiff.
I can hear it roar at start, then it quiets down. Once the temp reaches 210F it starts again and doesn't stop.
 
Originally Posted By: Trav
This makes me wonder about the radiator itself. Maybe partially clogged?


Yeah may have been too late. When was the coolant changed prior to this time?
 
Originally Posted By: favilac
Hi.

The temp rises quick to 210F and it stays there, until I get in stop and go traffic. Then it goes up to 235-240. Once I get to speed maybe it goes down to 220, but it never gets down to 210F.



That does seem to point to the fan not working up to par. The belt tension is good right?
 
Originally Posted By: mechanicx
Originally Posted By: favilac
Hi.

The temp rises quick to 210F and it stays there, until I get in stop and go traffic. Then it goes up to 235-240. Once I get to speed maybe it goes down to 220, but it never gets down to 210F.



That does seem to point to the fan not working up to par. The belt tension is good right?

Good point on belt tension. Given the age of this truck I would easily believe that the tensioner is weak and the idler pulleys need replacement.
 
I tend to agree with the clogged rad idea, or an ineffective water pump. How is the heat? Is it scalding hot? If you run the heat with the blower on max does it cool the engine down? If you stand by the driver's door hinge with it idling is the fan throwing lots of heat out below the fender?
 
If the fan clutch is good it should be pumping a whole lot more volume of air when hot than it does cold. If that's all good and the shroud appears to be intact and the fins of the radiator look good, my next suspect would be an eroded water pump impeller. This truck has a cap on the radiator itself, right? With the cap off, open the throttle enough to raise RPM just a hair above idle. The water level should drop noticeably. When you let the throttle go it should come right back up to where it was.
 
If you have to replace the fan clutch I would go with the torqflo. I have one on my 98 1 ton chevy truck with the 454 and it works great. Before I installed it, the temp gauge would be at the 210 mark all of the time. Now it stays a lot lower. I also had a GM mechanic recommend one of these if I didn't want to use OEM.

Wayne
 
Thanks for the input guys, but yes, it's the fan clutch. Had it checked this morning.

Now back to the first question. Which one? The torqflo severe duty from AZ, or what appear to be a dorman from Napa.

Given the heat here, I'm leaning to the torqflo but the reliability concerns me... as most things from AZ do
wink.gif
 
With an average of 110 deg F in the shade, you may want a heavy duty Flex fan with no clutch.
And it still may be hot when sitting still -not moving.
 
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