4.3L cooling system
 

i was just wondering if anybody would know what would cause a rad to not take fluid from the res? had engine at operating temp, turned it off let it cool down and the rad was low but the res fluid level did not change. Has new rad cap, rad hoses and t-stat. Put dye in the system and could not see a leak anywhere on block, exhaust or in the oil. could a water pump wear out and not flow properly? could the rad be blocked? Also the lower rad hose is cold when at operating temp. Any sugestions? Need input. Thanks in advanced.

RE: 4.3L cooling system
 

If the lower rad hose is cold and the upper is hot, I would suspect a plugged rad.
Take the rad cap off and run the engine to temp and CAREFULLY look into the rad and see if you can see coolant flowing.

RE: 4.3L cooling system
 

A leak in the system would cause the fluid to not be drawn back into the radiator from the res. A bad radiator cap would also cause this to happen as would a plugged transfer line between the rad and the res.

Depending on the outside temperature, the lower hose could be cold while the upper hose it hot. That is the function of the radiator after all...

I would start by replacing the radiator cap with a Stant safety cap.

RE: 4.3L cooling system
 

O.K. I will try another new rad cap. I took out the res and flushed it and then installed a new hose from the res to the rad. The biggest mystery to me is where did that loss of fluid go. It ran for a couple of hours yesterday with dye in the system and could not see a leak anywhere with a UV light. could the water pump get weak and not leak? P.S. this will be the third rad cap I have tried. The vehicle has about 150K on in with original water pump and rad, and about two weeks ago there was a cooling system flush done at a shop. If I have to I will replace the rad and thew water pump if it will fix the problem. I'm at the end of the idea rope here guys! anything else you could give me would be appreciated. Thanks

RE: 4.3L cooling system
 

how is the heat in the cab of the truck?

RE: 4.3L cooling system
 

the heat on the interior is hot! it has not worked that good in years. Plus I flushed the heater core three times now.

RE: 4.3L cooling system
 

I just sentchu an email...

RE: 4.3L cooling system
 

I did not receive your e-mail i hope my stupid AOL did not block it. thanks 2002XTREME

RE: 4.3L cooling system
 

I think I just set it up so no e-mails will be blocked. try it again 2002XTREME. thanks again

RE: 4.3L cooling system
 

You may have a blown head gasket and the missing coolant is going out your exhaust. Something you might want to look at if you have no coolant in your oil. If left alone this can warp a head.

RE: 4.3L cooling system
 

I think you may be right about the head gasket. So on a whim I went to Autozone and bought a bottle of this stuff called "Blue Devil" it was $60 it says that no mater what type of coolant leak you have it will fix it guaranteed or your money back. A last resort before tearing the hole motor down. I will right back to let you guys know if it works.

RE: 4.3L cooling system
 

Whats your oil pressure at?? Is it higher then normal?? If your losing coolant that badly I would check the oil dipstick tube to see if its a milky brown!! If so it could be your intake manifold gaskets that went out its one of the more common problems with our engines!!

RE: 4.3L cooling system
 

The oil pressure is about 40 psi at idle. I put that "Blue Devil" in about a week ago and have not lost a drop of coolant since then. I will keep my fingers crossed. So far it is a damn good product.

RE: 4.3L cooling system
 

Hope it works out for you!