Overheating, replaced radiator and thermostat. Please help!!!

[PineappleRanger503]

Hello everyone,

My truck is overheating and I am having some difficulty trying to pinpoint the problem. Hoping I can get some help and ideas on what may be the problem and/or what I may be doing wrong or incorrectly.

I had a pretty noticeable cracked radiator which I have replaced with a brand new one. I also changed the thermostat with a new one and am 99% sure I put it in the correct way (just because that is one question I have been asked).

I bled the old coolant, flushed it, and replaced it.

While burping out the radiator after filling it with new coolant, the truck is fine. It gets to normal operating temperature and doesn't get any hotter. However, when I drive, after a few blocks the temperature slowly spikes up to high?!

A few buddies and friends of mechanics still think I have air trapped in the cooling system. I have burped it out multiple times for long durations, and it still seems to overheat once it starts to drive.

I've done a block test to rule out any issues with the gasket, and haven't seen and/or detected any leaks from the water pump, any other place under the hood, or in the vehicle.

Any help, advice, and even more questions that some of my friends haven't yet asked would be most appreciative!

 

[adsm08]

Water pump is shot. The 3.0 is good for rotting the fins off the impeller. It will be OK at idle, but the reduced flow shows up when you start revving the engine up.

 

[PineappleRanger503]

Thank you adsm08!

I'll give that a look and fix. Hoping it will be the answer to this.

 

[McCormack]

A few buddies and friends of mechanics still think I have air trapped in the cooling system. I have burped it out multiple times for long durations, and it still seems to overheat once it starts to drive.

Not likely to have air trapped. Everything on the output side of the 3.0 coolant system runs uphill towards the top of the radiator and there's no where for air to get trapped, so any air in the system will work it's way out on it's own.

Just throwing out ideas = 3.0's are notorious for blown head gaskets/cracked heads, so even though you did a block test I wouldn't completely rule out a blown head gasket as the cause of your overheating problems.

 

[55trucker]

Just curious,

what did you use to pressurize the cylinders to be sure that there is no seepage into the coolant system......

do you have a coolant system pressure tester as well to check the coolant system..

 

[timd]

Lower radiator hose could be collapsing when at road speed/rpm. Feel if it is easy to compress.