91 b2200 starts to over heat after running for 20 min,replaced thermastat , radiator looks fine no leaks it is orginal.it smokes blue is when i fire it up but goes away should be valve guide seals...dont think its the head gasket? Should i replace s\the water pump before the radiator i think its cheaper, Any thoughts?

 

Check to make sure your water pump actually works before you change it, turn on the heater and see if your getting heat, if you have heat then your water pump is working, if not the pump is dead. When does it overheat? Idle, driving, stop and go e.t.c.

 

Is it an electric radiator fan, or mechanical?

 

Does the clutch for the fan work? When does it overheat? Is the radiator boiling over or is it just the gauge that says hot?

 

Well if its overheating when you get on the freeway its not the fan. Are you using any coolant? You can test the fan to be sure by spinning it by hand WITH THE ENGINE OFF when the engine is hot, the heat makes the silicone in the clutch get more viscous transferring more power (speed) to the fan, when the clutch is bad the fan is VERY easy to turn all the time. Is your radiator cap in good shape? If its original it might be time to replace it, I prefer the ones with the lever on them to release pressure.

 

Since you seem to have a clutch fan, without it running, can you turn it by hand?

 

Yes i can turn the fan when its turned off ,it turns fairly easy with some resestance,i'm really getting frusterated checked the oil for water and did not see any indication of water

 

You can always get this NAPA AUTO PARTS it checks for exhaust gases in the coolant, if it stays blue your good if it turns yellow you have a popped gasket. Or you could borrow a pressure tester and pressurize the cooling system overnight then with the spark plugs out crank it over and see if water flies out of the cylinders.

 

Hey guys so my damn truck is still overheating i have checked everything,the truck still is over heating after about 20 min of run time it has the original radiator i flushed it out real good and put new antifreeze in ,how do i know if it is getting enough flow? water pump is good ,thermostate is new, head gasket seems fine ,no white smoke ,no antifreeze in the oil,I would like to know if the Radiator is working before i go get a new one deu to a limited buget. Any help or words of wisdom?

 

You can unhook both radiator hoses (save your new coolant!) and pour water in one side and see how much comes out the other side, if you fill up one side of it and not alot is coming out the other that means its plugged. Also when its hot and the fan is on the air being blown out should be hot too, if not plugged radiator. You can put your hand on the front if you can get your hand there and feel the actual core of the radiator, plugged tubes should be cool compared to the rest of the radiator, working tubes should be hot at one end and cooler (but not cold) at the other as they lose their heat. Some radiator shops will do a flow test for cheap and tell you if its bad. Did you try the block tester or do a pressure test?