Too much exhaust from Idle Relief Holes?

[cdenkers]

Good Afternoon,
I have a 1984 MerCruiser 305 with an Alpha Outdrive. I was on the lake the other day and noticed that there was an excess amount of exhaust coming out of the Idle Relief Holes on the Transom Plate when in idle. When I put it in drive, the exhaust starting coming out of the prop which is normal. Is there maybe something blocking the exhaust going out of the prop? I cant really notice an amount coming out of the Idle Relief Holes when we are moving.

Any help would be much appreciated. Thanks in advance!

 

[bruceb58]

Re: Too much exhaust from Idle Relief Holes?

Sounds normal to me. You having a problem?

 

[cdenkers]

Re: Too much exhaust from Idle Relief Holes?

We just bought the boat a couple weeks ago and I never really noticed it before. There is just a lot of exhaust coming up next to the transom plate when its in idle. I just want to make sure that there isnt something wrong or something blocking the normal exhaust passages.

 

[jtmarten]

Re: Too much exhaust from Idle Relief Holes?

Normal for both of mine.

 

[cdenkers]

Re: Too much exhaust from Idle Relief Holes?

Thanks guys!

 

[ziggy]

Re: Too much exhaust from Idle Relief Holes?

sounds normal to me too. they are relief holes. the water that can't exit the prop leaves through the idle relief holes. water could be pretty restricting when at rest...

that said. if your exhaust shutters fail and fall off (usually from an overheat condition), they can make it to bell housing and get hung up on the shift shaft and that could be and exhaust restriction. or they can blow all the way through too. it just depends on your luck if they fail.

a pic of mine while running.

i was surprised to see water exiting the relief holes at speed. but i don't think there's anything wrong with my rig. i just never looked before...

 

[Simoniz]

Re: Too much exhaust from Idle Relief Holes?

Yeah - All normal.

The clue is in the name of the holes, "Idle relief ports, ie they relieve the exhaust gases of having to go all the way down to the prop when the engine is at idle.

When my boat is running at speed, water comes out of the ports as well. I wouldn't worry about it.

 

[cdenkers]

Re: Too much exhaust from Idle Relief Holes?

How would I know if my exhaust shutters have failed or fallen off? Is there some way to test to see if they are still there? What would the consiquences be for them not being there, really bad?