I bought new 350 190hp engine from Summit. Engine heats up after idling for a 3 min or so. Test driving the engine runs at 190* but when I stop for 3 or 4 min the temp starts going up fairly fast. It cools back down once I am rolling again . I had new radiator installed with engine. My truck has AC and it has a 3 speed automatic trans. I found out they "advance auto" sold me a radiator for my truck with no AC and it had a 1 1/4 thick core. They replaced that radiator with one for my truck with AC and it had a 2 3/8 core. Both radiators were aluminum . When I got the 2 3/8 core radiator home I found it was way to thick to work on my truck with the original mounting brackets and insulators. I assumed the thickness of new radiator was making up for the AC condenser blocking air flow. I also have a small trans. cooler in front of the condenser. "Autozone" has a rad. for my truck with AC but it looks exactly like the one from "advance auto"that is for vehicle with no AC. Both of the radiators from both stores match the width,height & thickness of my stock radiator. My stock radiator has always worked fine, it is copper and brass, not aluminum and plastic like the new ones. It was damaged during removal and is not usable. Where do I go from here? Please send me thoughts or suggestions. I cant afford a $500 OEM radiator. Thanks for your help. Big Nick

What kind of fan setup do you have on the radiator?

It has stock fan with stock fan clutch.

My first suggestion would be to check it to make sure the shrouds are put back together like they belong, and also check the fan clutch to make sure it is locking up at temperatures above 210. You should be able to hear the fan like crazy when it is locked up, and it will move with engine speed. Also it would be good just to double check the condenser to make sure there is not an excessive amount of bent fins.

It'* sounding like there is just not enough air flow through the radiator at idle, and the fan should be keeping that under control if it'* working properly. Also make sure that all of the air is bled out of the cooling system as well.

All the condenser fins and the transmission cooler fins are straight and clean. I notice when I crank it up with hood open I can feel and hear the fan blowing real hard then it tapers off and quietens down. When it overheats the fan doesn't ever blow or sound like it does when I first crank it up. How can I test the fan clutch. My neighbor said to safely hold it still when I crank engine and when I rev it up I should feel the fan trying to pull out of my grip. What do you think about the radiator situation I mentioned? Should I try AutoZone'* aluminum radiator for my truck with AC? All air is bled out of system.

This looks rather interesting, and may be worth a read: Part 1 -BAD Fan Clutch Troubleshooting Case Study (GM 4.8L, 5.3L, 6.0L)

I think I will go buy the radiator I mentioned and maybe a fan clutch since I have it torn down this far. I may decide to test the fan like mentioned in that article you sent . It will be late tomorrow before I find out anything. Thanks for your help, I will return and post my findings. If you think of anything else, let me know. BigNick

Just got threw testing and my problem is solved!!! I put a new fan clutch on it and man what a difference in the air flow. I used the heavy duty model and so far I cant make it get over 185*. I did also put the new radiator on it but I feel sure it was the fan. Thanks for all your help! BigNick