Lately, I've noticed that my truck will run hot (by gauge) if I floor it It will immediately heat up and then cool back down shortly after I back off. I've already replaced the thermostat. Any ideas? It's got 45K miles, and the fluid doesn't appear to be real dirty. BTW, it was doing this before making any modifications.

thanks,

Chris


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96 F 150 SC 4x4, 5.0, All Black, Custom Cat Back 3 Chamber Flowmaster with dual outs and 3.5" tips, Superchip.

 

This is a *long shot*, but how strong is your coolant mixture? Anything more than a 50% mixture can make your truck run too hot. 1/2 coolant and 1/2 water (about -34°F) is perfect.

Coolant is great for raising your boiling point, but it *holds in* the heat MUCH longer than water.

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-=[ Tuxedo Mask ]=-

1998 Nascar Truck

Superchip JET Power Pulleys AIRAID DynoMax Super Turbo with Roush tip Royal Purple performance synthetic 5w30 3.73 performance axle SVO 9mm wires

 

Sounds like your lower radiator hose might be collapsing. It's supposed to have a spring (coil of wire) in it to keep it from collapsing under suction of the water pump. Squeeze the hose to see if you can feel the spring inside the hose. If it's missing or corroded, get a new bottom hose with the spring in it.