Gear Lube leak on Mercruiser Alpha Gen 2

[marco_0521]

I have a 4.3L alpha Gen II Mercruiser engine and drive. Last year, the boat was working OK. I took out the drive last winter and stored in my garage. Now, I disassembled the upper and lower part so that I could change the impeller for this year. Replaced the everything as per the manual. The parts seemed to be the same although the oil seal carrier was yellow (the one that was there was green I think. The oil seal carrier already had o-rings installed and had all the parts, o-rings that the one I took out had. It was exactly the same other than the color. The kit (mercruiser) had a bag with more o-rings, but I couldn't find where to put them.

I have the Mercruiser manual # 14 and followed the instructions, or so I thought. I filled the reservoir lube first (as per the manual) purging the air before installing the drive. Then, I placed the drive in the down position and filled the oil from the bottom up taking the air vent out and placing it back once it was full. Oil leaked from the propeller shaft. I placed the drive in the up position and oil leaked from a small hole on the lower unit on the starboard side.

After researching this forum, I decided to empty all of the lube, and pressure test the drive with compressor air. When I apply air, I can hear that air is coming "freely" (it does not seem to be a small leak but a large one) out from the inside of the propeller shaft. I tested the small hole on the startboard side of the lower unit, but no air pressure came from there, either because the leak on the propeller shaft is so big or because there is no leak in that hole.

I only replaced the water pump and didn't do anything else on the propeller shaft, it makes me believe that I made something very wrong when re-assembling the drive.

Questions,

1. Should I take the whole drive out or just the lower part and test it?

2. Is there anything that I missed completely on the water pump that could have caused this?

3. Any ideas on what else can I check.

Your help is appreciated. Thanks,

 

[Bt Doctur]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

can you show us what you changed,part #`s

 

[marco_0521]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

I couldn't see all the parts in that picture, but if you go to page 5 of this link,

http://www.boatfix.com/merc/Techbk/94/94hsc2.pdf

you can see the parts I replaced.

23 - gasket
17 - face plate
24 - gasket
27 - impeller
22 - water pump
25 - face seal
26 - the four screws
18 - Carrier
28 - Key (Little piece that forces the impeller and the drive shaft to rotate together)

The Carrier (#18) was the one that came in yellow. Thanks,

 

[tommays]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

I would bet you Missed the small black quad ring that seals the upper and lower

You supposed to hold it in the lower with a drop of bellows glue so it stays in place while you install the upper

 

[marco_0521]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

Seems worth giving it a try. I don't remember having installed that ring. I will be taking the drive out and will try to put it back. It might take me over the weekend but I will post the results as soon as I do it.

Thanks.

 

[marco_0521]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

Tommays,

Took the drive out, separated the upper and lower and put that seal. Put the drive back together and pressure tested it. Very tight! Put it back into the engine, and filled it with lube. Not a drop.

Thanks very much.

 

[Dakota47]

Re: Gear Lube leak on Mercruiser Alpha Gen 2

Good call Admiral..