92 Mercruiser Alpha 1 w/350 Mag water intake issue

[tarheelebbtide]

I have a 1992 350 Mag Mercruiser with Alpha 1 drive unit. I had the engine rebuilt last year and somehow the mechanic "lost" my Alpha 1 unit. He replaced it with a newly rebuilt unit that is a 96 model Alpha 1. The unit seems to be working fine with one exception...I cannot run the boat trailered because all of the water from the flush muffs simply streams out the hub of the prop. I'm doing the exact same things I did with the old unit in place, but all of the water comes out of the prop hub and none through the bellows.

It might also be worth noting that my boat was modified to put the exhaust thru hull above the waterline before I purchased it. I don't know if that makes a difference or not.

I have placed a large tub down and trimmed the drive down into it and it picks up water fine using this procedure and water flows from the bellows. It also does fine in the water. Should I be concerned here?

 

[jerryjerry05]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

If it's not overheating I wouldn't worry.Jerry

 

[dgopetactical]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

If it's not overheating I wouldn't worry.Jerry

I agree with Jerry, as long as your temps are good your fine.

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

Thanks guys. That's pretty much what I was thinking as well, but it never hurts to have a second (and third) opinion! My temps are just fine when running at 1000 RPM or better, but it does tend to warm a little when just idling. I know my impeller is good as I replaced it at the end of the season last year.

 

[wca_tim]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

I don't know... I would worry. That would seem like something is installed incorrectly or cracked / broken.

The water pump housing, or perhaps the tubing that runs between the lower and upper units is cracked or missing.

At the very least it's inconvenient, otherwise, a minor detail, but you're likely running at with the drive exhaust cavity filled with water... a good bit of added weight while the boat is on plane and also putting a lot of the already heated water back through the engine. You also need to be able to flush the engine and do routine maintenance tasks while it's on the trailer. If nothing else, you might want to be able to fire it up and make suer everything is running well before a day when you've got plans.

I would want that particular mechanic to buy me a NEW replacement drive (SEI / aftermarket would be acceptable, but definitely not someone else's cobbled together mess), and if that's not going to happen, I would want to have someone(else), probably myself, split the drive and see what's wrong... it could be a quick easy fix, but it could be something that would create a bigger problem down the road...

To be real frank, I would be finding a different mechanic as well... lost drive? not able to run on muffs? That's nuts!

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

Trust me, it's never going to any of these yahoos around here ever again. I'll just work on it myself from now on.

 

[Don S]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

It might also be worth noting that my boat was modified to put the exhaust thru hull above the waterline before I purchased it.

If you have thru hull exhaust, you better have water coming out the exhust thru hull with the exhaust. Otherwise, you have something hooked up wrong and the exhaust would be getting extreamly hot inside the boat.

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

The water is coming out of the thru hull. Like I said, the boat appears to be operating as normal, but I just can't for the life of me figure out why the water from the flush muffs runs back out the prop hub.

 

[fishmen111]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

You need to trace the water intake and discharge routes or take it back to the yahoos. Something doesn't sound right. Do you have selectable exhaust or purely thru hull? When you say the muff water exits from the prop, is this after circulation or immediately? When you say no water through the bellows, are you refering to the standard exhaust bellows or a portion of the thru-hull?

 

[CharlieB]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

It should NOT run warm at an idle.

You have a potentially serious problem with leaking water at the water pump transfer tube, not fitting correctly or the wrong transfer tube for your model water pump.

Either way it MUST BE LOOKED AT before you damage your engine.

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

It's not recirculated water coming out of the hub. It's the water straight from the muffs as it does it without the engine running as well. There is no circulated water coming out my prop hub as the exhaust is completely thru hull. Again, this is only an issue when using it with the flush muffs. If it's in the water, it picks up fine and has water coming out of the above water pipes as it should. It doesn't run hot at idle, just a bit on the warm side and there is not much water coming out of the pipes at idle (though there is water coming out). I don't think it's a transfer tube issue or it wouldn't be happening on the flush muffs even with the engine shut off. It's like the aperature that allows water to enter the lower unit for the impeller to pick up is open directly to the prop hub somehow. Again, in the water, everything is fine....normal water flow and good temps though just a bit warmer at idle.

 

[wca_tim]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

I just noticed the "tarheel". Where are you located?

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

I live in Raleigh, work in Chapel Hill, and play at Lake Gaston!

 

[CharlieB]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

If the water pump upper OR lower housing is warped then water pressure
of the garden hose will cause your 'leak', OK fine as long as the pump remains submerged, HOWEVER, once one plane and the water pump is 'uncovered' then the impeller begins to suck AIR, reducing water flow to the motor.

Now do you see the problem that is developing?

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

So Charlie, your thinking is that one of either the water pump or the lower housing is warped?

 

[wca_tim]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

You've got a leak somewhere in there...

We were on Jordan on the 4th... I'm further East these days but used to live in Durham and Chapel Hill.I've still got some friends in the area there and if you like can ask who they're using for boat mechanics these days and whether they would recommend them...

 

[tarheelebbtide]

Re: 92 Mercruiser Alpha 1 w/350 Mag water intake issue

Where down east? I grew up in Tarboro. The boat is up at Gaston full time.