First its a 99 Ram 1500, Reg cab 4X4 360/5.9L Alittle back ground, Its my father in-laws truck that he says is his but the wife drives it to work everyday, Anyways i told him to get rid of the truck because every year it has a problem with the cooling system but in the past year it has blown 3 radiators and ruined 2 water pumps now when i say blow a radiator i mean it even blew the plastic tank apart with a loud boom as it was siting shut off in a parking lot after it was driven 20+miles. Now if it was just blowing the radiators i would think head gasket leaking into the cooling system causing enough pressure to blow the radiator apart but for it to also be going through water pumps it has to be something else right? Anyone else ever go through this before?

 

Sounds like you have a badly blown head gasket/cracked cylinder head on that truck. I'd connect a radiator pressure tester to the radiator, start the truck up and see if the pressure quickly rises once the truck starts. If so, a blown head gasket/cracked head is the main cause. The radiators on those trucks aren't the greatest, since they have plastic tanks on them that are prone to cracking. If you plan to keep the truck, install an all-aluminum radiator - CSF 2969 after fixing the head issue.

 

Agreed. The stock casting on the heads on these trucks are pretty weak from the factory.

 

Shouldn't the radiator cap be relieving excess pressure?

 

It should, however, if the pressure is really excessive, it likely can't bleed it off fast enough - also, there could be a case of stop-leak in the mix, causing some issues, too.

 

Pressure in the cooling system only hits around 15lbs from the test that was done, I am just lost on this one because from what i can tell there is no reason for it to be doing this, The truck runs great plenty of power, never over heated (That i know of like i said his wife drives it and she doesn't know jack about cars.) There is no stop-leak in the system its been flushed so many times,

 

If system pressure is only 15psi, and your new radiators are failing (bursting), that should be a warranty claim.

And I don't see how 15psi would harm a new water pump (even the cheapest version).

 

I know thats why i am so confused with this, I really never seen one blow the plastic tank apart before this thing, i think it was in this order for the last 3 rads, First one the plasic tank blew a nice hole where the top hose connects, second one the tank started leaking where it connected to the core along with the water pump, 3rd one a vain came apart in the core and also the water pump, All that was in the past 1-2years. I could understand one being defective but two along with the water pumps.

 

Were they both the same radiator from the same place?
What is the failure mode of the water pump?

Either they're grossly substandard parts, or you're well over 15psi... pick one.

 

I'm really confused as well because the plastic tank has an open tube at the top to release coolant if it gets too full. It doesn't even hold pressure at all.