96 Dodge Truck Radiator

96 Dodge Pickup Radiator

Several weeks ago I had to have a new water pump installed on my 96 Dodge Pickup. All has been fine until cold weather arrived and I noticed my heater was not putting out the amount of heat it used to. After checking a few things under the hood this is what I have discovered that has me puzzled – the bottom radiator hose does not get hot. The hoses do not pressurize nor does the whole system. You can take the cap off any time with out any pressure being on the system. This is a new cap also and I also had a new thermastat installed. I guess my question is do I have a problem with my radiator not pressurizing and the bottom hose being cold and soft. The top hose gets hot but is soft due to no pressure. What’s going on here? bcarll

How’s the coolant level in the radiator? It could be a bad thermostat. Can you undo the upper radiator hose and see the thermostat? You may need to remove the thermostat housing. Even new ones can break. It cannot be the water pump if the truck is not overheating. I had a water pump completely freeze up on me once, and the engine temperature shot up like a rocket.

Pressure builds as temperature goes up. But, if it cannot heat up properly, it will not build pressure. The thermostat holds the coolant in the engine block to regulate the temperature of the engine. The heater circulates this coolant stored in the engine block. But, if the thermostat lets the coolant out at too low a temperature, then neither the engine or the heater can get warmed up right. And if there is not heat, then there is no pressure.

Your lower hose will not be as hot as the upper. That is where the cooled water from the radiator goes into the engine. Your system must be full to be pressurized. If you have a radiator cap that is right on the radiator, it won’t pressurize unless the coolant is full right to the top. It has to get some flow through it or it won’t.