c-man405

I swapped a 5.3 into a 69 c10 and I'm having an issue of It wanting to run hot sometimes. I have changed the thermostat, water pump and have pumped water through everything(radiator, block, heater core) to make sure it all flows through. My upper radiator hose gets hot and stiff as can be while the lower radiator hose is cool and soft. The radiator is warm on the drivers side and cool over on the passenger side. The weather is in the 20's-40's. around here so it's not hot outside. I'm running the radiator and expansion tank from the 2000 suburban that the engine came out of. Any ideas would be helpful
Thanks Carter

gagliano7

Sounds like you have air in the system.

Project GatTagO

iTrader: (7)

If the lower hose is not getting hot it means the thermostat is not opening. First cause of that is air in the system. I've had really good luck back filling the block through the steam crossover tube. It's a bit tedious, but it works like a charm. Get a small funnel, take your time, and you'll be amazed how much water you'll add to the system.

Andrew

c-man405

I've been filling it up through the upper radiator hose to fill the block and then filling up the radiator but I will try that.
Thanks

Project GatTagO

iTrader: (7)

The upper radiator hose attaching point on the water pump is not the highest point in a LS cooling system, the steam vent is the highest point on the engine. This is why I put a long hose on the steam crossover and make sure that it is well above the radiator when I back fill.

You can also jack up the front of the car so that all air bubbles will tend to move forward and up, but this is usually not necessary.

Andrew