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She is a 1995 with a 5.0. I have no pressure in my upper radiator hose, not even light pressure. The hose gets very hot but when squeezed I can feel no water flowing through it. Replaced the thermostat and ran it for 20 minutes and still nothing. Not really sure where to go from here=(
The truck is at my shop so I wont be able to look into suggestions until morning but id like to know what im looking for when I get there.
Im not sure if its the cap. I drove it after replacing the thermostat, the engine temperature was approaching the red zone but the radiator cap was cool to the touch. I opened it and cool water came shooting out. So it seemed it was holding pressure back.
Last edited by Machinist; 09-29-2010 at 06:49 PM.
Okay, you have replaced the thermostat, we can eliminate that.
With the cold engine idling and the radiator full of water with the cap off,
after a several minutes, when the thermostat opens, you should see water start to come out the top of the radiator, that is if everything is working as designed.
As dr bowtie said; it could be calcium & rust has buildup inside your radiator and the water cannot get through it, down to the bottom to start the cycle over again.
As you know the Water Pump pulls the water from the bottom of the radiator,
then pushes the water through the bottom of the engine and out the top through the thermostat into the top hose and back in the radiator.
Have you replaced the Bottom Radiator Hose recently?
The reason I'm asking is there is a spiral spring inside the bottom hose to keep it from collapsing and if the old spring was not put in the new bottom hose, the water pump will not be able get enough water volume.
A Water Pump will always pump if it can get enough water to the impeller.
It may leak water out the weep hole, but it will still pump. The impeller is turning when the engine is running.
I just picked the truck up yesterday for dirt cheap so I have no idea about the bottom hose but I will defiantly check for collapse and deposits in the morning. If its neither of the two would it be safe to assume the water pump is shot?
It will be a fun toy once I get it operating correctly. I need to hunt down all the vacuum leaks and see if that fixes the CEL.
If you do not see a new bottom radiator hose on this truck,
that's probably not the problem.
I'm leaning toward a plugged radiator unless you can tell it is fairly new.
It doesn't sound like the water pump is causing your problem,
even if it was leaking, it's still pumping!
The impeller would have to come-off inside the water pump housing for it NOT
to pump plenty of water and you would hear noises if that had happened.
I've never heard of an impeller coming off; not saying it can't happen though...