93, 4.3 runs hot

Purchased a 93-S10 used with 195,000 miles. runs fine, but hot.
Temp gauge didn't work, replaced temp sending unit in head, gauge read hot. Replaced sender again from GM dealer this time... same hot reading.
Replaced 195 thermostat with 180, better but still reads hot, 200 to 220 to 240. I replaced the fan clutch, due to exccessive play in shaft, no change in temp reading... Borrowed IR Temp gun, thermo outlet reads 180, temp sending unit in head reads 240.... The aluminum rad has been replaced as well. Ideas? Water pump ? Wrong head gasket - blocked water paseage? Help

I would try back flushing, prestone makes a kit you splice in the heater lines to back flush your system...worked great for me... good luck

make sure you are using the correct mix and that there are no air bubbles in the system. more coolant than water can cause this. i would flush the system completely. also your gauge could be off as well.

Thanks, I did verify the correct 50-50 mix when I replaced the thermostat. Someone has worked on the engine, but to what extent, I don't know...

Also, replace your rad cap and go and get a professional complete reverse flush at a shop.

You will be amazed at seeing the gunk that comes out.

This usually causes the problem.

Check EGR valve.Non functioning EGR can cause engine to run hot

If an EGR is faulty, it will usualy throw a check engine light.

All - Thanks for the ideas, Flushed the system, no change, Checked the EGR, the valve itself was good, the comp controlled valve that controls it, bad. Replaced it, Truck runs better, more power, smoth idle cold and hot, but still ran hot. Replaced the Water Pump, problem fixed. Now I need to change the thermostat back to 195 for more heat..... Thanks again.

Make aure you replace the rad cap as well, the stock unit is prone to leaking air into the system.

It is cheap.

How much was that computer controlled valve for the EGR?

Should be around US$150 but you can get them cheper off of ebay.

The part was 64 dollars at my local parts store, it has 2 vacume hoses, and a 4 wire connector plugged into it. its bolted to a metal bracket next to the throtle body, passenger side.

Oh, you have the diaphram EGR valve.

Yup, looks like the old original type, vacume operated....lucky for me...