Water entering ujoint bellows while on muffs

[TomCz]

Our 1987 3.0L Alpha One has served me well for 27 years. Last summer we noticed greasy water in the bilge. Investigation disclosed that the water was entering from the u-joint bellows vent into the transom and bilge - and it was happening when on muffs in the driveway as well as in the water. I disassembled the outdrive last fall and am preparing to reassemble with various new parts - bellows, shift cable, water pump impeller - when I came across some internet comments and a diagram that claimed a faulty "oil seal in bell housing", specifically the seal on the shift assembly, the vertical shaft at that goes through the exhaust port in the bell housing, can cause water ti enter the ujoint bellows. Could this possibly be correct? If so, that could be my leak - BUT how can water enter the ujoint bellows though the vertical shift rod from the exhaust port???? How can there be water in the exhaust system? Thanks!

 

[wrench 3]

A leaking shift shaft seal will leak water into the cavity were the shift cable enters the bell housing. If it then leaks past the large square cut "o" ring that goes into the bell housing ahead of the drive it would get into the drive shaft bellows.
The cooling water mixes with the exhaust as it leaves the exhaust manifolds but on the muffs I wouldn't expect the percentage of water in the exhaust or the back pressure to be high enough to force water into the bellows. A more likely source would be the "o" ring on the water passage between the drive and the bell housing.
Another thought is that you have a bellows leak, water is staying in the bellows when the boat is removed from the water and it doesn't leak into the boat unless the motor is running. The bearing is rotating or the "U" joints are splashing it up.

 

[Bt Doctur]

BUT how can water enter the ujoint bellows though the vertical shift rod from the exhaust port????

It usually dosent enter that way.

How can there be water in the exhaust system? Thanks!

Water enters the exaust stream from the riser/elbow. This is what cools the exaust so the rubber components dont burn.

Water enters the bellows from a missing or dislodged water inlet O ring

 

[harleyman1975]

Yeah like BT Doc says the exhaust manifolds are cooled with water and the water mixes with exhaust gases and passes out through the gimble assy and the prop hub. Hope this helps.

 

[Bondo]

Water enters the bellows from a missing or dislodged water inlet O ring

Ayuh,.... That's where I'd start lookin',.......

 

[TomCz]

Thanks, guys! I pulled the lower unit last fall and, after receiving your comments went back to recheck some of the parts. I found a few things that probably contributed to water in the bellows: 1) a small (1/4") tear in the bellows - I missed that - probably because my mindset was thinking it couldn't be the bellows if I was getting water while on muffs...)2) some corrosion in the shift cable. As wrench 3 suggested, perhaps the rotating u-joints was somehow forcing the water through the transom vent while the boat is running on muffs. The water inlet O ring is still in place and flexible, so that's unlikely to be the issue. I seem to be missing an O ring at the top of the lower unit vertical drive shaft, Not sure if it just dislodged when removed and lost - or never replaced when the impeller was replace some years ago.

Anyway, I'll be replacing the bell housing gaskets & O rings, shift cable, u-joint, exhaust and cable bellows. I'll replace the oil seal in the bell housing exhaust with the upgraded version as well as replacing the water pump and various seals and gaskets in that area.

When I removed the water pump base yesterday to install the new one I found a piece of metal under the base - round cylinder, appx 1/2" long X 1/8" dia. See picture - its just sitting there at the 6 o'clock position (below) where I found it. Can anyone venture to say what that is? I bought the boat new and I don't believe the base was ever removed to replace the impeller, and I can't see where it broke off anything or where came from:


Thanks again!

 

[Bt Doctur]

could be one of the locating pins in the water pump base.

 

[TomCz]

Yup. I see from the exploded diagrams that the water pump has a single alignment pin - which is still attached to the base. Where this one came from I have no idea. I bought the boat new and for some years the dealer did all the servicing - perhaps decades ago the pump was replaced and a pin was accidentally dropped and not retrieved? . Oh well... on to other matters. Thanks for the reply.

 

[Rick Stephens]

The o-ring cut into the top of the shaft coming up out of the lower unit through the waterpump is no longer used. It does more seal damage than good. So normally just left off.

Rick

 

[Fishermark]

The o-ring cut into the top of the shaft coming up out of the lower unit through the waterpump is no longer used. It does more seal damage than good. So normally just left off.

Rick

Yep. As Rick says, don't put the o ring back on the drive shaft.

 

[TomCz]

Thanks Fishmark & Rick. My Mercruiser Service Manual #6 (1992) shows the old (with groove) and new (without groove) drive shaft designs. Manual states to check that the drive shaft O ring is in place during reassembly. My Seloc Manual (1991) describes the shaft seal as "very important" but I half remember a long time ago seeing or hearing someone say to leave it off. I guess I should buy new manuals every ten years. Thanks for the reminder & heads up.

Is it suggested to replace the water pocket cover gasket and seal while I have the unit apart, given the age of the unit and my issue with water?

Thanks again!

 

[Fishermark]

There is a service bulletin from Mercruiser somewhere - it noted that more often than not the o ring would get caught up in the upper seal and cause a leak - the opposite of what it is supposed to do!

Is it suggested to replace the water pocket cover gasket and seal while I have the unit apart, given the age of the unit and my issue with water?

I would leave that alone. You can take a look at it and see if it is deformed by heat. Otherwise, the chances are good you will break the bolts off holding it on, and then you are in trouble.

 

[TomCz]

Thanks. During lower disassembly 1) a screw holding a trim sensor broke, 2) it took time to get another bolt to budge and, 3) finally, I had to drill out and remove piece by piece the shift cable to bell housing fitting. Nice thatI have the time to do this, but I'm not looking to create more trouble, particularly in an inaccessible spot. All in all, the boat looks good and has problem free, compared to what other seem to experience. I just want to do what I need to keep it running well enough so we can enjoy it on our local lake 10-15 afternoons a summer. No heavy lifting, like pulling skiers for hours on end like we did when we were younger! Just easy cruising and floating!

 

[Rick Stephens]

Agree with Fishermark, if the water pocket isn't melted leave it be. Water on both sides of the gasket anyway.

Ric