Ok, so I switched out my old leaky radiator which did not overheat for a brand new one from rock auto.....and now I overheat! The coolant is not circulating through the system. Motor heats / overheats yet heater does not blow hot. I know coolant is not circulating because there is no coolant in upper hose when I take it off the engine. I have tried to bleed the system but llevel does not go down when I fill radiator and I know the system is not full because I drained about 1.5 gallons of coolant before I took the old one out and the new one will only take about 1/2 gal. I have replaced several radiators on gl /beats and never had this problem.

 

Suggestions?

 

I should have let the old bugger alone.

Sounds like you're having some sort of clog between the radiator and the water pump.....kinked hose? something stuck in the tstat?

No on the hose. Cant imagine a clog, will tear apart and find out.

I've seen this on lifted EJ swaps before - the radiator being a lot higher than the engine causes problems with getting the fluid in them. It takes some effort to get all the air out. If you don't have one of these they are really useful:

 

http://www.amazon.com/Lisle-24610-Spill-Free-Funnel/dp/B001A4EAV0

 

It allows you to create a reservoir of coolant above the filler neck and then massage the air out by pumping the hoses. Works quite well for Subaru's in general.

 

Also make sure you have an OEM thermostat with a proper jiggle pin in it. Otherwise air will be trapped till the thermostat opens and since EJ's use cold-side control that never happens as the engine heat rises and the thermostat stays cold even when the engine is overheating.

 

GD

Otherwise air will be trapped till the thermostat opens and since EJ's use cold-side control that never happens as the engine heat rises and the thermostat stays cold even when the engine is overheating.

 

GD

 

This is my thought. If there's fluid in the radiator, but it's not circulating through the engine/heater core at all, it sounds like the tstat and pump are still in air, which means it isn't getting from the rad to the engine.

 

 

 

 

Also, a clean gear oil bottle with the bottom cut out works great for bleeding out air in the same way.

Had one new radiator that the casting flash on the hose inlet had never been cut out. Stupid possibility I know, but check your holes.

This is my thought. If there's fluid in the radiator, but it's not circulating through the engine/heater core at all, it sounds like the tstat and pump are still in air, which means it isn't getting from the rad to the engine.

 

Right - with no jiggle pin there's no way for the coolant to flow from the radiator into the engine except through the upper radiator hose. The thermostat effectively caps off the lower hose which turns the radiator into a dead-end. At that point the only way it's going to get into the engine is by flowing down the upper radiator hose and that's at the opposite end of the radiator as the filler neck on the EA81's. Very slow process for air to get back through the radiator and out the filler neck and for coolant to run back in and take it's place.

 

GD

Simple fix: Fill the engine through the upper hose before attaching it to the radiator.

 

Have never had an issue with overheating after a coolant change using that method.

You guys nailed it.......if only I had read your solutions in time.

 

Replaced thermostat, same situation. Took off upper hose and dry as bone. So decided to fill from upper hose......worked perfectly.

 

Never had to do that before.

 

Thanks for the tips.