I did a 460 swap recently and am having trouble getting the temp to stay normal. What happens is when driving around keeping a steady speed the temp is fine. When idling it's fine. Under hard acceleration and towing, fine. But, when I am slowing down, say, getting off the interstate, the temp goes through the roof. I have seen temps as high as 240 within 45 seconds of slowing down. If I rev it up a little the temp drops back to normal. I have tried 2 themostats, had the rad cleaned out, changed the fans out. What are your thoughts? Is it possible the water pump is cavitating? Bad pump? Bad timing cover? Any help is appreciated...

 

how's your fan clutch?

 

Solid fan on it right now, no clutch.

 

Could be a worn impeller on the water pump or wrong size pulley.

 

Hopefully you upgraded the radiator along with the 460 and you aren't using a 240/300 6 cylinder radiator with it.

Josh

 

Sure sounds like a water pump problem.

 

Seems weird though, the temp is fine under load, and yet while SLOWING down the temp climbs.

Need more info on the 460. Did you rebuild it? Is it a newer engine that used a serpentine belt? Where are you installing the temp sensor?

Josh