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Anyone tried an outlet thermostat on an EJ?
GeorgeL - June 16th, 2006 at 03:28 PM

Considering the problems that some have with making their EJ engines cool properly with the stock coolent inlet thermostat, I was wondering if anyone has simply removed the inlet thermostat and installed a thermostat in the more conventional location at the coolant outlet?

I've been talking to a fellow whose problem is undercooling due to his generous front-mounted radiator introducing a gulp of cold water to the engine when the thermostat opens on a cold day, starting a pattern of thermal cycling. We thought that an outlet thermostat might moderate the cycling. Anyone have experience with this?

George

klashniv - June 16th, 2006 at 03:58 PM

George,

I have read about drilling a small hole in the original thermostat so that there is some flow even with the thermostat closed, therefore, reducing the temperature difference when it opens.

Have also read that this might help with bleeding air out of the system too.

helbus - June 16th, 2006 at 07:10 PM

I drilled a 6mm hole in our thermostat to allow the lower thermostat to operate in a satisfactory manner.

shaihulud - June 16th, 2006 at 08:09 PM

Well I'll be blowed. I have assumed that the thermostat on my EJ20 is an outlet model. Now I'll have to reverse my planned plumbing design. Thanks for this thread.

GeorgeL - June 17th, 2006 at 06:10 AM

Quote:
Originally posted by shaihulud
Well I'll be blowed. I have assumed that the thermostat on my EJ20 is an outlet model. Now I'll have to reverse my planned plumbing design. Thanks for this thread.


Ah, unintended benefits! Good!

I'd heard of the enlarged bleed hole to moderate the temperature in the radiator. The theory is sound, but for those of us who might travel in subfreezing temperatures it might result in long warmup and perhaps even overcooling.

Even with an outlet thermostat you need to have a little bleed hole to move warm water from the engine to the thermostat so the thermostat can sense the temperature. I wonder if Subaru's intent was to create a design where the radiator flow could be zero until the engine reached operating temperature?

George