Mercruiser Upper leaking oil

[jackmperk]

Hey all, I have a 1993 Bayliner with a 3.0 mercruiser. All last summer I was getting water in the lower unit gear lube, so I was replacing the lube after every weekend. I thought the issue was going to be with the seals on the lower so I separated the lower today to have it repaired. However, I forgot to drain the lube before splitting the lower from the upper and lube started coming out of this spot right above the shift linkage on the upper (see picture).

Is this hole supposed to be here? I'm also assuming this is how I'm getting water in the lower unit? I also don't understand why I haven't seen oil leaking from this before, unless somehow I broke it when I was splitting the lower from the upper.

I'm guessing the previous owner of the boat didn't change the lube and there was some water in it and it froze and broke one winter.

Is my only option to replace the upper with a new or used one?

 

[Bt Doctur]

For oil to leak from there most likely is the upper carrier input shaft seal
Remove the upper to see if there is oil in the bellow

 

[jackmperk]

Thanks for your quick response! So that hole is supposed to be there?

 

[Bt Doctur]

When you remove the upper it will become clear on how the shift system works

 

[Rick Stephens]

Splitting the cases with them full of oil dumps oil everywhere. There is a oil passageway between the two cases that then is open and the drive shaft that comes up from the lower leaves a 1 inch hole for oil to drain out of as well. Once you get things back together, and ALL the oil out, do a pressure test of the assembled drive. Only way to really tell where any leaks are.

The Adults Only section has tips on building your own pressure tester, and the Mercruiser Service manual is an essential guide to what you are looking for.

 

[XJessen89]

I have this exact same issue on mine. I did not disconnect the speedometer hose quick connect when I removed my lower unit, and now my drive oil continuously leaks. I wonder if I tore/split the hose inside the bellows, or if I have another separate issue as it appears here. Same symptom though.

Rick/BT - does that hose continue through the bellows? Or is there a separate enclosed system that holds drive oil in the upper part of the drive, with the hose coming down to the lower unit and another hose running back to the drive oil reservoir?

 

[Rick Stephens]

I have this exact same issue on mine. I did not disconnect the speedometer hose quick connect when I removed my lower unit, and now my drive oil continuously leaks. I wonder if I tore/split the hose inside the bellows, or if I have another separate issue as it appears here. Same symptom though.

Rick/BT - does that hose continue through the bellows? Or is there a separate enclosed system that holds drive oil in the upper part of the drive, with the hose coming down to the lower unit and another hose running back to the drive oil reservoir?

You should probably start your own thread.... however, a couple answers to your questions:

The connection between upper and lower is a small (<1/4") passageway with a small o-ring sealing it.

The speedometer hose when disconnected does nothing at all and will not leak any oil or water.

There are no rubber hoses connecting upper and lower.

The oil line to the oil reservoir is independent of everything else.

 

[ktownman96]

The oil line to the reservoir is leaking on my boat. I’m trying to trace the oil line to locate the leak. It leaks into the bilge area. I can see the oil on the ground from the bilge drain. Any ideas on where the leak might be?