Idle Relief

[quicktach]

What is the purpose of the idle relief holes on a Mercury 25 HP (1987) ? Is water ever supposed to come out of the holes when the engine is running and water is also coming out of the "pee" tube ? The faster the motor runs, the more water comes out. I just pulled the lower unit and put it back together - since water is coming out the "pee" tube, I assumed I got the copper tube in the grommet/neoprene tube under the power head.

 

[Texasmark]

Re: Idle Relief

Idle relief is a method of relieving the back pressure on an engine when at rest. With the exhaust coming out of the prop, at rest it is a good way below the surface and it takes pressure to force gasses out. Engines don't like this so exhaust holes were installed above the water line to allow the engine to breathe. Cooling water is ejected from the engine with exhaust gasses for one thing to help to keep the exhaust plumbing cool; unlike the exhaust on an engine that is run in the air.

Find something else to worry about sir! Grin.

Mark

 

[quicktach]

Re: Idle Relief

Thanks. Never noticed it before either ...