Put new radiator in, now wants to overheat

[schwarze_crewcab]

As the title says, I just put a new radiator in my truck. Let it sit outside to let it get up to temp and make sure all is good. Went out after a few minutes and it was almost to the red. The radiator didn't feel particularly warm to the touch. And I have no heat. Everything was fine until this point, other than the leaking coolant that precipitated the radiator change. I also had to replace the coolant fitting going into the intake, and it came out in lots of little pieces.

Any ideas?

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[95z71performer]

Maybe try a thermostat and new temp sensors that would be my first try is to go after the cheaper things to save some money

 

[TylerZ281500]

did you bleed the radiator? i usually let the truck idle with the cap off and heat on hi inside the vehicle. if you get an air bubble or a few it will overheat and act funny.

 

[phule]

No heat and cold rad. Start with a tstat

Adam

 

[92GMC]

Sounds like you have an air pocket.

 

[poncho62]

Yep...air in the system. Drain it and add coolant slowly with the engine running and warm.

 

[schwarze_crewcab]

Thanks guys, nothing quite so dramatic. When the tstat opened it sucked it down to where there hardly wasn't any water in the radiator. Everything I'm around drops the level down a little bit, not nearly as much as this thing does. Another thing different about gm I guess.

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[woody31]

to keep that from happening in the future.take a new thermostat and drill 2 or 3
5/16 holes in the flat surface install as usual and when you fill the radiator it will push the trapped air out the holes back thru the top radiator hose,,hope this helps...cheers...

 

[Scrufdog]

Anytime I do coolant work on a vehicle without an air bleeder built into the system I do the following, always works.

Remove the thermostat housing and thermostat, as well as the radiator cap. Fill coolant resevoir halfway in between hot and cold lines. Fill the engine through the themrostat hole until just about full. Then top off the thermostat hole by slowly pouring coolant into the radiator. This eliminates air in the engine. Reinstall thermostat and housing, then fill radiator. Leave radiator cap off and start engine, turn heat onto high. Coolant level will likely drop, so keep it full. Idle the engine for about 5 minutes then reinstall the radiator cap, engine still running. Sit in the drivers seat and if the gauge gets above your normal running temp, rev the engine to 1500-2000 RPM and hold it for about 5 seconds. This pushes coolant up to the thermostat if more air has made its way into the engine. Watch the gauge until you see the thermostat open, revving about every 20 seconds, the gauge will drop about 30 degrees or so during a cold start. When the gauge drops rev the engine engine. Let it idle about a minute more, then shut off the engine. Wait a few minutes and remove the radiator cap, careful it will be hot and under pressure, do it slowly. Top off coolant if needed. If it seems like you are adding an awful lot of coolant at this point, you may need to repeat the 'engine running, rev, watch gauge' thing again.

It sounds like a lot to do, but its quite simple and the 20 or so minutes of doing this keeps you from having problems later.

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