Water leaking into the boat through the engine coupler area, Still!

Jsand

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Jul 31, 2015
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1994 Mercruiser 5.0 L, Alpha 1, Gen 2 outboard. I have pulled the engine thinking that maybe the frost plugs had popped out on the backside of the motor. No, they look brand new. I replaced driveline bellows, exhaust bellows, shift cable boot, and the suction water line hose, o-ring, gasket, gimble bearing, etc. Put it all back together, and took it to the river to test it. I backed it into the river and got up their and looked. WATER is pouring in from the drive line coupler area, and i didn't even start the dang motor.
I am lost!
Where is this water getting in at?
Could there be a way that it is coming out of the top of the upper unit and following the drive line through the bulwark and exiting at the coupler?
How would the water get past the gimble bearing?
We are talking a darn good flow of water.
What else am i missing here!
I double checked all the hose connections around there, everything checks out.
Boat shops around here don't have a clue or i am not important enough for them to care. I bet they would care if i offered them the business to figure it out and fix it.
Anyhow i guess i am done for the year, kids start school next week, and i will have until next summer to figure it out.
 

Bt Doctur

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Aug 29, 2004
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did you use adhesive when you installed the bellows? If it is coming from the coupler/flywheel area you have a cracked block
 
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biggjimm

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Jul 15, 2015
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If you're sure It's coming from the transom side of the coupler area, & not the engine side, I'd say It either has to be coming in thru the u-joint bellows or perhaps the gimbal housing is not sealed against the transom & letting it in there??? I too would not think it would flow that fast thru the gimbal bearing itself, but I don't know?? The intake water hose going from the transom to the engine is not leaking?
 

brokerancher

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Aug 14, 2015
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I bought a used boat and had a problem with water coming in also. Found a hole in the bellows and thought that would fix it but didn't. Turned out to be the depth finder had a thru hull transducer that was installed at the factory and became loose. It would start leaking as soon as you put the boat in the water.
 

Jsand

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I know it is coming from the transom side and i know that it has a good flow even when the engine isn't running. The pump that is in the lower unit, does it allow water to flow through without having to run? I think my next step will be to pull the outboard unit off again and stick a hose into the suction or water inlet and see what that does.
 

Rick Stephens

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Aug 13, 2013
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The pump normally will not allow any water through unless it is turning. Even putting a pressurized hose on it won't get water to the engine.

You have to have an outright hold like a slipped off cable bellows or the gasket and bolts loose on the hydraulic manifold.

Rick
 

Bt Doctur

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re-reading your post could the water be coming in from the Y pipe? Would be visable looking at the area where the trim lines come thru but not visable looking down from the top of the housing.
 

Jsand

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re-reading your post could the water be coming in from the Y pipe? Would be visable looking at the area where the trim lines come thru but not visable looking down from the top of the housing.

I thought to look there, but i can't get past that the water is coming out of the area where the coupler bolts to the flywheel.
 

Rick Stephens

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I thought to look there, but i can't get past that the water is coming out of the area where the coupler bolts to the flywheel.

Only two things there - cracked block or a bad core plug. Problem with that - should only leak from either when the engine is running.
 
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Jsand

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Only two things there - cracked block or a bad core plug.

Pulled the engine and had it inspected. Nothing there. Motor doesn't even have to run for water to pour out there. I backed it into the river yesterday to test it and as soon as the back end was in the water, it just started to run right through there. I dint even get a chance to start it. It hasn't ran since the engine was pulled.
 

Rick Stephens

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Yeah.... I got you. I think you should take your mirror, cell camera, back it in and fire it up. Get wet. Figure it out. I'd be crazy after pulling the motor and not finding it.
 

Bt Doctur

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Remove the inlet hose from the therm housing or ps cooler and put the garden hose there.
turn the water on and see if the engine leaks ,if not see below.
The very worst case:
pull the drive
pull the engine
cap the Y pipe openings
reinstall drive
put in water
 
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Jsand

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Jul 31, 2015
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Remove the inlet hose from the therm housing or ps cooler and put the garden hose there.
turn the water on and see if the engine leaks ,if not see below.
The very worst case:
pull the drive
pull the engine
cap the Y pipe openings
reinstall drive
put in water

I didn't think about attaching water hose to there. That will be my next test. I also thought about covering up the water inlet suction holes on the lower unit and sticking it in the water to see if water comes in then .
 

Watermann

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Yeah there's not a route for water to pour in from the location your indicating without the motor running. Considering all the bellows are in good shape then for water to pour in then it's either the Y pip has a hole rotted in the bottom or as mentioned, the hydraulic line manifold has an issue. To just back the rear of the boat in the water and have it pour in makes me think there's a big hole back there somewhere. Try having someone flooding outside transom assembly with a garden hose while you watch inside to see where it comes in. Also try running the boat on muffs but I would stay clear of lakes or rivers until you get it repaired.
 
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smokeonthewater

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The swivel pin I mentioned is directly over the coupler area.

Could easily be your problem.... Pull the motor and back the boat into the water. Then you should be able to find your leak easily.
 

thumpar

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Try putting the tongue of the boat way up and filling the bilge with water to see where the water comes out at.
 

smokeonthewater

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No never do that....
First the starter will be underwater long before you find a leak and second you will force water into any holes in stringers, floor, and transom.
 
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