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Hi guys,

So our 2007 5.7 with 225k is overheating. It’s noticed mostly when towing our 22’ trailer, but temp will climb when not towing, if going up a grade.

When towing, If I keep it in drive, even on a completely flat surface the temp will climb about 3/4 or more. Up any sort of hill it will be pegged in the red. At this point it is not possible to tow anymore with the truck. Toyota dealer replaced the radiator once (old one looked fine) and thermostat twice. And gave the truck a good bill of health, apparently they can’t replicate the problem without a trailer attached and I’m tired of dealing with the stealership.

Im really thinking at this point it’s gotta be a blown head gasket. However, I did a radiator leak down and everything looked good. No oil in the coolant etc. I also did one of the Napa color changing fluid tests to check for exhaust gasses in the coolant. All looked ok.

I’ve noticed if I keep the rpm’s way up the temp will come down, not sure if that helps anyone. My buddy has an old square body Chevy with a confirmed blown head gasket and that’s his trick to get the temp to come down too.

I’m at a loss right now. Help is appreciated. Thanks
 

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Thanks for the reply. I have checked by hand and all seems ok, assumed the dealer also checked this but probably shouldn’t make assumptions. I was under the impression it doesn’t do a whole lot a freeway speeds?
They likely just saw it was spinning and called it good. The fan clutch is supposed to lock up more when temps climb, like towing or plowing.

I have seen more than a few fan clutches cause issues and get passed off as good. I would try to replace it, see if it changes anything. Also the water pump itself may be bad, not as likely since it's probably been replaced before at the miles you stated. But still possible, since I have actually seen where the impellor more or less corrodes away.
 

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I got beat to it, water pump and clutch fan. The clutch fan is an easy repair even if you are not mechanical you can probably replace it. Then if that does not solve the over heating replacing the water pump would be in order. I would also assume it has been replaced at least once with 225,000 miles on it but you did not mention that.
 

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I agree with the above. Fan clutch, water pump, thermostat. And you might get one of those infrared laser thermometers and shoot the engine when it shows hot to see how hot it really is (in case you are getting a bad temperature reading from the temp sensor). You can get them at Walmart for under $20, and now is the time to make the investment while you can convince the wife you need this fancy tool! Ha.

The only thing I would add is don't drive it hot. You will ruin the engine doing that. You have to shut if off and let it cool down. If you are in the red, you need to stop now and shut it off. Watch that gauge and don't run it hot.

The engineers have made some warning lights red, and some yellow for a reason. Red means you have to stop. Yellow means you can continue with care.
 

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In addition to the above you should consider installing the oil cooler from a Sequoia. Initially, they were installed on the Tundra but a cost saving measure was implemented. Every vehicle could benefit from an oil cooler. While it may not fix the problem you are currently having it can add longevity to your engine.
 

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little late, but being on 07, worth while checking the rad cap if its still original, been seeing a few of the recovery valves breaking off on the cap, and it falls into the coolant manifold and restricts coolant flow, causing an overheat when loaded
 

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I think the radiator cap should be replaced like every five years or so along with your hoses. Maybe the stealerships use that as an excuse for more business living here in hot Phoenix.

Also, your fan works hard when towing! Pulled a 7000 lb travel trailer up a 20 mile grade when it was 115 degrees outside. Stretch of I-8 out of the Imperial Valley to San Diego. About halfway up the fan was making more noise than the engine with the volume of air it was pulling through. We had the a/c on also.
 
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