Engine gets hot at idle

[Dannyboy1966]

Originally Posted by tucsonjwt

Is the water pump actually pumping coolant? Do you see evidence of a water leak (rusty water trail) at the weep hole on the bottom of the water pump?

If you need a fan clutch, I would stick with AC/Delco factory part. I have not had good luck with flex fans. From the symptoms you describe, it sounds more like a bad fan clutch to me. When the engine is overheating and you pop the hood to check the engine, do you see the fan moving?

If ll else fails, a rare but possible coolant passage obstruction in the engine block could be the cause. A power flush might help that. You would have a shop with a power flush machine do that, along with a cleaning agent.

Tucsonjwt, The water pump is doing it's thing, I've had the Rad, cap off, and see movement (Though not as much as i can remember looking at other vehicles), but movement none the less. No water leaking out the weep hole, that was the first thing I checked while I was laying on the ground replacing a fuel line to the pump. (hard for me to get up and down off the ground so killed two birds with one stone).
I've found the fan clutch is grabbing like it should, and the blades are pitched in the right direction. It's never overheated fully, but yes the fan is moving. I can shut the truck off and go into a station to pay for gas, and after i'm done, start the truck up, and you can hear the fan roar for a few seconds moving air, then it slowly levels out.
I back flushed the system last fall, when I had it all open replacing hoses, and the thermostat (now it wasn't opening when I replaced it, but works now), only thing I didn't get flushed was the radiator.
As I said on a previous post, I think the previous owner replaced the Rad. with a single core when he swapped the Diesel out and put in the 350. Maybe he damaged the original during the swap. I found this out when I went to the GM Heritage web site, and downloaded my trucks build information. It's suppose to have the HD radiator, and clutch fan in it. Thats a great site by the way.