454 over heating

The P 30 engine, (Chevy 454) in my 1996 motorhome has started to over heat as soon as I stop for a light. The temp gauge will go up to the red and stay there until I pull away. As soon as I up the RPM's the temp will go back to normal. I have noticed a very slight increase in temp when running but not much. I have 80K miles on the engine. I had it flushed a couple years ago but it didnt seem to help.

I do not seem to notice any temp increase at highway speeds or under loads, like pulling a steep hill.

I hate to pay money to have some one guess and throw parts at it. Suggestions please.

Ed, in Pittsburgh, PA

Reply to
Ed
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A competent mechanic / technican won't guess, he or she will diagnose the problem and then repair / replace things.

We can sit back and guess.

  1. Water pump failing, not moving water at low rpm's.

  1. Clogged or partially clogged radiator.

  2. Basic air flow - is the air path to the radiator clear? Is the outside of the radiator clogged with debris?

  1. Collapsed hose - have the hoses been replaced? All, upper. lower, and heater core hoses?

  1. Is there any coolant loss? If so where's it going?

  1. Has the coolant been changed? You said a flush several years ago. Depending on how much it sits, the climate, etc, your usage may require more frequent changes than the manual would suggest.

Just a few things.

Reply to
Miller

Here is a quick check you can do fairly easily. With the engine hot, pull the dog house and see if the fan will turn easily. If so then the fan clutch may be bad. Regards, JR

Reply to
JR

a marine would tongue test the fan

Reply to
samstone

Reply to
None4U

One of the several things I do for a living is refrigeration. A condensor (does same thing as a radiator on a vehicle) can look clean, but be retaining heat. Refrigeration guys use chemicals to clean the condensors on refrigeration equipment.

A couple days ago, I was fixing a refrigerated case. The condensor was dusty, so I rinsed it out with water. The temps were still high, so I used coil cleaner lilquid, and more water. And, then, the temps went down.

It is very possible that your radiator has some grease and oil and road dust on it, and is retaining heat. I've never heard a garage guy mention chemical cleaning of the outside of a radiator. But, it may make a difference.

Reply to
Stormin Mormon

It sounds like you're low on coolant....... you may have a leaky intake manifold gasket, or worse. My truck used to do that..... although at a much higher mileage.

Reply to
Chad Fernandez

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