Testing shift shaft seal in gimbal assembly

KHE

Member
Feb 28, 2012
238
West Michigan
Boat Info
1997 Sea Ray 240 Sundancer
Engines
Mercruiser 5.7L EFI alpha 1 Gen 2 drive
I thought it would be best to start a new thread - I have an inconsistent gear oil leak to the ground on my alpha 1, gen 2 drive. I removed the drive last fall prior to putting my boat in storage. Recently, I drained the gear oil and there was no evidence of water in the drive. I pressure tested the drive and it passed.

I inspected the shift shaft seal in the bell housing and there is 1/32" of slop in the brass bushing at the lower/bottom of the bell housing and there doesn't appear to be any seal there. Brake cleaner ran right through which means water can get into the exhaust cavity area.

I then sprayed the upper seal where the shift shaft lever is and the cleaner did not run through so i think that seal is good. There is no water in the u-joint bellows area and the gear oil that was drained did not have any water in it.

I don't see a breakdown of the shift shaft seals in the Mercury Marine parts diagram under the bell housing. Is the slop normal in the lower section of the bell housing brass bushing? It seems as if there should be a seal to keep water out of the exhaust cavity but there appears not to be one in my unit.

I checked the hose from the reservoir and it is dry - no oil residue. Where could the leak be coming from?
 
small o ring that seals gear oil from drive to bell housing, may have shifted or fell out when reinstalling drive. just a thought
 
small o ring that seals gear oil from drive to bell housing, may have shifted or fell out when reinstalling drive. just a thought
Are you referring to the seal that is pressed into the drive that mates up with the check valve on the gimble housing?
 
It looks OK to me - I don't see any damage to it. When the drive is installed, the gasket surrounds that check valve area.
 
I looked at the seal on the outdrive again under some decent lighting and there are some nicks on it but it doesn't seal against the face. It is a double lip seal that seals on the inside diameter. It is approximately 1/32" recessed into the face of the drive. I inspected the check valve on the gimble housing and it was recessed into the gimble housing approximately 1/32". A picture of the seal is attached.

Does this seal just pry out? I may just replace it.
 

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I didn't like the nicks/gouges that were in the seal. The local marina had one in stock so I bought it and will change it out in the next day or two. It came with a new spring and ball. Then it's time to install the drive. If it leaks again, hopefully, I can trace the leak path. Hopefully, the new seal fixes the issue.
 
I replaced the check valve seal in the outdrive. It's been one week since I installed the outdrive and so far, no leaks.

If the wind would calm down, I could actually use the boat. It seems like March lasts for 2-1/2 months in Michigan...
 
I spoke too soon... A couple of days ago, I noticed a spot of oil the size of a quarter on the driveway. The oil is coming from the shift shaft area. in the direction of the red arrow.
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I inspected the shift shaft seal in the bell housing and there is 1/32" of slop in the brass bushing at the lower/bottom of the bell housing...
Pretty typical, as the shift shaft will tend to find its own center on the lower unit's shift shaft.

...the lower/bottom of the bell housing and there doesn't appear to be any seal there. It seems as if there should be a seal to keep water out of the exhaust cavity but there appears not to be one in my unit.

There isn't a seal at that point, as you have lake water on the bottom and half of the lake coming out of the top from the exhaust. It's basically a water-lubed bushing. You do need a good seal on the upper half, as that's what keeps the water out of the u-joints. However, even if that were to leak, you wouldn't see an oil drip, as there's no oil in that cavity; only u-joints and grease.

I pressure tested the drive and it passed.
Yeah, that's what's bugging me too. The auto-oiler's suspect, but you've changed that seal.

With no water in the gear lube and a good pressure test, it has to be something external. When pressure testing, was it as a complete assembly, or did you split it upper/lower? If not, I would suggest splitting it, blanking off the oil transfer hole, and testing the lower itself. If it passes, it has to be something in the upper. My guess is that it's the shift-shaft seal in the lower unit. That, or your engine's passing oil out the exhaust...
 
Pretty typical, as the shift shaft will tend to find its own center on the lower unit's shift shaft.



There isn't a seal at that point, as you have lake water on the bottom and half of the lake coming out of the top from the exhaust. It's basically a water-lubed bushing. You do need a good seal on the upper half, as that's what keeps the water out of the u-joints. However, even if that were to leak, you wouldn't see an oil drip, as there's no oil in that cavity; only u-joints and grease.


Yeah, that's what's bugging me too. The auto-oiler's suspect, but you've changed that seal.

With no water in the gear lube and a good pressure test, it has to be something external. When pressure testing, was it as a complete assembly, or did you split it upper/lower? If not, I would suggest splitting it, blanking off the oil transfer hole, and testing the lower itself. If it passes, it has to be something in the upper. My guess is that it's the shift-shaft seal in the lower unit. That, or your engine's passing oil out the exhaust...

The oil color is the blue/green color of gear lube but I can't get enough on a paper towel to determine if it smells like gear lube. One thought is it could be spline grease (which is a similar color to gear lube) that is separating and the liquid portion is dripping to the ground somehow but that seems pretty far fetched to me. It is definitely coming from the location where the shift shaft passes through the bell housing where I marked on the parts diagram.

When I pressure tested the drive it was a complete unit - I did not separate the upper portion from the lower gearcase.
 
Is your gear lube hose connector leaking oil? The tube from your gear lube reservoir connects near the shift linkage in that area. Is the connector cracked or hose split causing a drip?
 

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