Hello everyone. I have a 98 Dodge Ram 1500 with the 5.9L V8. I have had a motor swap to a newer one with less miles and on the new engine I have done the following repairs.

Plenum Gasket Kit, bypass the heater core , timing chain & gears, water pump , & and all these with good feel pro gaskets.

My radiator is good no issues and good flow, however I’m still losing coolant somewhere . Truck runs amazing so I doubt it’s a head gasket as my oil is clean and I get no hissing or steam when it does overheat. I want thinking maybe freeze plugs somewhere. Anyone have insight?

 

Do you see any coolant on the ground where you park?

IS the engine overheating? That is one of the signs of a blown headgasket.......

 

no coolant on the ground at any point even when overheating or overnight.

 

Double check the bypass tube from the water pump. If it isn't installed properly it will weep out of there and burn off before dripping down. And the aluminum water pump doesn't show green. Took me a year to figure that one out.

 

If it's overheating, need to find out why.

 

The bypass hose was done in a effort to stop the overheating because I found out I had a bad heater core (passenger floor board wet) and I’ve still had issues since doing the bypass hose

 

my only comment on why I don’t believe it’s a blown head gasket is because the truck runs beautifully , just drove it 8 hours to pick up a 98 V10 and no issues until this morning when I went to go to work. My oil in the V8 is pure and clean as can be. No milky color and I don’t get any hissing or steam. It can only be head gasket if it blew outwards away from a water jacket which is typically not a common issue. I plan to get a extenda-mirror and check all my freeze plugs for leaks

 

I didn't mention bypass hose. I wrote bypass TUBE. Where it installs on the water pump is a common leak point. The metal tube needs to be properly mounted and sealed with RTV into the pump or it will leak and you'll never see it.

Also, the pump itself can leak and evaporate causing little to no evidence. But if the truck runs great and it just burns a little water, I would just keep an eye on it and eventually it will give more symptoms/leak evidence.

 

Do you have a air pocket in the intake? Does the t stat have a jiggle valve or hole in the t stat to let the air out? And when does it start to overheat? Will it still overheat traveling at 60? The coolant loss may be causing the overheating if you don't fill it up again. Take a flashlight and look underneath the motor and look for signs of leaking.

 

Get a UV test kit and a bottle of water based dye. Add it to your cooling system and drive a bit. Then USE the safety glasses and black light penlight from the kit and look for a greenish yellow trace of dye. I'll bet it's either the weep hole under the water pump, or as another poster said, the bypass tube. If it's the weep hole, your water pump is on it's way south for the winter. You can also grab the fan and try to wiggle it. Any play in the pump shaft and your pump needs replacement.