Heater not that hot

[freeheel4life]

Congratulations, and nice work. Always nice when an experiment pans out.

[duffymahoney]

Crazy to think that a 3/16 hole was all that was needed for my heater to work like 10x better.

[JohnnieMo]

Could you post a picture of where you drilled the hole? I'm not following this at all. I would love heat at idle.

[duffymahoney]

If you have the low idle Y fitting, then on the 5/8 side, just drill the tiny hole out to 3/16. I don't think new boats have the low idle Y. Basically with this setup hot water from the intake goes through the heater core and goes back to raw water intake just before the pump. The small hole is meant to suck water through the core by increasing pressure at idle. I just think it was too restrictive for my large core or?

[talltigeguy]

Am I messed up to think that mine was wide open on the small side?

[duffymahoney]

Am I messed up to think that mine was wide open on the small side?

Yep. Not wide open. Tiny hole in the 5/8 fitting side. They admitted that for some reason it doesn't work on all boats. The engineer thought maybe chevy based 350 motors have less pressure water pumps. Which makes it not work.