The good old radiator

Phil, I agree that in many, many instances, the OEM part is the best. I belong to a car forum for AC Cobra replica owners, and again and again, I see problems pop up from guys using aftermarket items. OEM may cost more, but I believe you get what you pay for. Nowadays unfortunately, you have to be aware of even dealers selling aftermarket parts. Ask them if they have both OEM and aftermarket, before buying the item. Now with that said, there are times where an aftermarket part works wonderful, and can save you serious money. Some parts are made for the OEM, but are repackaged and sold aftermarket as well..roll of the dice..

Curious flyfisherman, as to the ratio of anti-freeze you are running? Anti-freeze also works as a coolant, so if your ratio is off, that could make a difference.
Some of the fellows running high performance vehicles highly recommend adding a product called "Water Wetter" for better cooling. Might be worth looking into..

If it's the original 92 rad..the cores may be plugged up, so ultimately a new rad may be the only solution.

Can you determine visually with the cap off or with a temp gun, or any other way if coolant is actually running thru the radiator?

Most common radiator failure is coolant leaking to the floor...
Next is fins packed with crud...
If the fins are clean, coolant is flowing, the radiator pretty much has to cool.

If you can look into the top with the cap off, you'll see the coolant moving when the thermostat opens.
Or this far into it just remove the thermostat and check for flow without it.

Check temp top and bottom with a temp gun.

Use a "third party gauge". I've been known to put my wifes oven thermometer into the top of the radiator to verify the temperature.

Not sure on your chevy, the F53's "look" like they have a temp gauge in the dash, but it's driven by the computer, and only has 3 positions, cold. normal. and really hot. never anything in between

Phils wrote:
When I worked at an auto parts store, we had a similar Chevy with overheating problems. The owner was a very qualified mechanic (and a supervisor of many). He'd tried everything, like you.

I'll keep this short, rather than the two pages I COULD write detailing all the things he tried and the results of each.

Bottom line: when he replaced the fan clutch WITH A FACTORY OEM PART, his overheating problem was fixed. (He'd had at least four new aftermarket fan clutches from different brands).

Phil

Same is true for Dodge trucks, the aftermarket just doesn't work right.

X 2 on the cheap clutch fans.

When I worked at an auto parts store, we had a similar Chevy with overheating problems. The owner was a very qualified mechanic (and a supervisor of many). He'd tried everything, like you.

I'll keep this short, rather than the two pages I COULD write detailing all the things he tried and the results of each.

Bottom line: when he replaced the fan clutch WITH A FACTORY OEM PART, his overheating problem was fixed. (He'd had at least four new aftermarket fan clutches from different brands).

Phil

Temp sending unit is pretty cheap, maybe you should just swap it out.

Before I did anything, I would first break out temp gun and see if your gauge is right. I would hate to do everything your talking about and find out gauge or wiring to gauge is bad.

does it boil over when the gauge shows in the red? have you checked the temp with an independant gauge?
BTC