Location of freshwater exit for Mercruiser Alpha 1 Gen when on muffs

[mk160]

Just replaced my impeller and on a test run on muffs water was coming out of the propeller area and not in the exhaust where I thought it normally did. When I put the stern drive up about 45 degrees the water exits with the exhaust where I'm used to seeing it. Is there an issue here? Appreciate any feedback.

 

[Scott Danforth]

on the hard at idle, it should be coming out the idle relief ports as well as a bit out the prop hub

 

[GA_Boater]

On muffs, cooling water can exit the motor anyplace through any exhaust port. Why? Because out of the water there is no back pressure.

 

[mk160]

Thanks. I modified my original post before reading your feedback. When I raised the drive to about 45 degrees the water was exiting at the muffler where I'm used to seeing it. I think that makes sense with your feedback?

 

[mk160]

And the idle relief ports are vicinity the exhaust?

 

[Scott Danforth]

Transom shield

 

[dubs283]

Thanks. I modified my original post before reading your feedback. When I raised the drive to about 45 degrees the water was exiting at the muffler where I'm used to seeing it. I think that makes sense with your feedback?

mercruiser sterndrives do not have mufflers, there should be an exhaust bellows attached to the gimbal housing exhaust flange and the bell housing exhaust flange. it's possible someone installed the bravo style exhaust tube?

in any case, running the engine with the drive at a 45 degree angle is not recommended, damage to the u joints and other components can occur hence the trim limit switch

the idle relief ports are located at the bottom of the gimbal housing on both sides, roughly 1" holes. if you are not seeing water exit through either holes it may be one or two broken flapper pieces are blocking them

 

[mk160]

I'm learning a lot, thanks. Since my last post I pulled off the lower unit again on a hunch. I had my wife help me put it back on and she caught that the guide tube missed the target, which I think, would explain the water coming out of the propeller and not the exhaust. So with her help I realigned everything. After a successful muff run I took it to the lake. Unfortunately, at 3k rpm it went up to almost 200 degrees (100 degree weather) but cooled back down to 160 when idling with the engine cover up. Tomorrow morning I'm going to back it into the lake with the hose from the impeller disconnected just to verify I'm getting good pressure. If that's good I'm thinking maybe I need to inspect the heat transfer unit (4") to ensure its not plugged.

 

[wshekar]

I initially thought the high rev was on the muffs (big no-no) but I see it was at the lake. 200 seems high for lake water even with hot weather.

 

[mk160]

I agree, way to high. Seems like it should have been closer to 160+. After I verify the impeller pressure I think the heat exchanger will be my next focus.

 

[mk160]

Went out early to the lake this morning to check impeller output (see video). I believe this is adequate flow? Little rough and exhausty as I just started the engine.