1989 OMC 5.7 Main Bellows Leaking

bpg28

Recruit
Joined
Aug 30, 2011
Messages
3
Hello - I've studied over many of the posts relating to the topic on this and other boards and can't yet find my answer. I can't say that I have seen them all, but a good number and I'm still scratching....

My issue is with a 1989 VIP OMC Cobra 5.7L. First of all, this is an eBay boat. Lesson number one for me - don't buy boats on eBay. It was completely rotten from the stringers all the way up to the dash pad. I have replaced everything from the hull up and did a complete custom interior adding many curves to the interior of what was a boxy older boat. New glass and some AWL Grip and she looks pretty good. But, I digress. I continue to get water in the main bellows despite seating and sealing it twice. What's been done:

First trip out with the boat and it nearly sank. The gimbal bearing gave up in the first 20 minutes of running and the shaft spun so out of control that it broke off a large chunk of the gimbal housing allowing water to enter the bellows and the boat rapidly. I managed to get it back on the trailer and the work began. While I had the gimbal housing off, I replaced the transom as well. A new (used) intact gimbal housing, new bearing, new seal, and new bellows later, I still have water penetrating the bellows. Both trips to the lake this summer (didn't get all of the interior and paint work done until August), I popped the bellows loose at the gimbal housing to find a LOT of water in the bellows. I yanked the drive off after the first time, coated everything with WD40 to knock any rust out immediately (it was rust free thankfully as I caught it early), and then replaced the gasket and slathered it with good silicone. It leaked on the second trip as well. I'll yank the drive tomorrow and shoot it with WD again to keep it from rusting.

My immediate suspicion was the seal at the bell housing. I don't have any sort of a keeper there to help the bellows seat to the housing. I don't find that there should be one in the manual either. It's just a friction fit at that point, and one that doesn't appear to me to be tight enough to keep water from penetrating there. I made very sure that the lip of the housing was very smooth and clear of any debris before I reseated the bellows (remember it's new) the second time. Because it was suspect, I added a bead of silicone to the bellows just aft of the seat. I didn't put any IN the seat (lip or the bellows itself), but aft of it. When I returned from the lake the second time, I pushed on the bellows to see if I could determine if there was water and it began to drip at the seat. Still leaving me to suspect that this is where my issue is. Am I missing something here? I don't recall the Seloc manual telling me to seat it IN silicone. Maybe I skipped over that?

I have also read some posts about the grease tube. I don't suspect it because I have crammed a lot of grease through it and haven't seen any leaking out of it. The zirk seems tight as well and definitely won't pull loose from the gimbal housing, but there is a considerable amount of discussion about it potentially being a problem, so maybe I need to look there?

I haven't seen any water leaking into the boat. There apparently isn't enough getting in to get past the o-rings on the main shaft. But, there seems to be between 6-8 Oz when I pop the bellows loose to check it.

With the custom interior and new glass/wood the boat is a bit stern heavy. The top of the outdrive sits about 1/2 inch below the water line at rest. I do not have any water penetration into the outdrive itself as multiple checks have yielded no milky fluid. The steering arm is approximately 1 inch out of the water at rest as well, but with no connection to the main bellows, I wouldn't suspect that regardless. IF I had water in the boat, I might, but all seems to be well there.

I replaced all o-rings throughout as well. Another suspect spot, however, might be the shift linkage as it goes through the bell housing. All that's there is a single o-ring. I did slather it in waterproof grease when I replaced and re-inserted it as well. Because the boat has thru hull exhaust, I left the exhaust bellows out of the mix. Since it won't use it at all, I determined it to just be in the way and no need to add it back in. But, that has little to do with the main bellows despite the shift linkage being exposed to that channel. Especially when you consider the exhaust bellows is perforated at the bottom to allow exhaust to more easily escape at idle. The perforations, of course, would allow water to reach the exposed shift linkage when the boat is at rest.

I am at a loss. Any help would be appreciated.
 

bigike

Petty Officer 3rd Class
Joined
May 25, 2010
Messages
77
Re: 1989 OMC 5.7 Main Bellows Leaking

I found my bellows not connected to the pivot housing, but i didn't get water in the boat... Fixing it the bellows was for an SX not a King Cobra, and the gimble housing where the bellows connects was beat up and broke off...

Anyways some one told me that the drive nose will push against the bellows in the pivot housing, the manual says to use permetex gasket sealant, that brown none hardening type, not silicon. I'm going to put the sealant around the pivot housing lip, install the bellows they put a little where the nose engages the housing.

How is the bellows lip fitting in the pivot housing?
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: 1989 OMC 5.7 Main Bellows Leaking

I don't recall the Seloc manual telling me to seat it IN silicone. Maybe I skipped over that?

I don't have an additional suggestion other than the Seloc manuals are generally "lacking ".......... Mercury suggests using a bellows adhesive in addition to the clamps that hold the main bellows on.

I can't remember what the Cobra manual indicates (because I gave it to the guy that bought mine) But if you're going to do major repair maintenance on your Cobra, you should have the OEM manual.

There should be NO water (ever) getting into the main bellows.......and if there is, you have either a bad installation, a crack in the aluminum housing, bad seal, etc......
 

bpg28

Recruit
Joined
Aug 30, 2011
Messages
3
Re: 1989 OMC 5.7 Main Bellows Leaking

I went through the broken gimbal housing lip issue. I simply pulled the housing and replaced it with a new housing that was intact. New housing (of course used) cleaned up well, and is smooth and without cracks. Considering I followed the Seloc instructions and didn't apply any permatex or bellows adhesive to either end, I suspect that's my downfall. An OEM manual may be in order - although I hope to be done messing with it soon.

I did note that the outdrive itself butts up to the bellows at the bell housing to push it firmly in place. That takes away my question of whether or not there was once some sort of keeper there to hold the bellows firmly to the bell housing. However, I also noted that I could tell, based on the condition of the silicone I had placed aft of the bellows at the bell housing, that the water was likely coming in there despite what seems to be a clean, tight fit of the bellows and the outdrive holding it in place.

My plan - unless someone else has something for me, is to purchase some bellows adhesive and apply that to both ends of the bellows. I'll add some around the nose of the gimbal housing and add some between the bell housing and the bellows. Either that, or I'll use some permatex on it and see what that gets me.

Thanks for the advice thus far!
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: 1989 OMC 5.7 Main Bellows Leaking

My plan - unless someone else has something for me, is to purchase some bellows adhesive and apply that to both ends of the bellows. I'll add some around the nose of the gimbal housing and add some between the bell housing and the bellows. Either that, or I'll use some permatex on it and see what that gets me.

I would lean toward the Mercury Bellows adhesive over the Permatex. There isn't a LOT of difference between how the two connect and are secured.
 

bigike

Petty Officer 3rd Class
Joined
May 25, 2010
Messages
77
Re: 1989 OMC 5.7 Main Bellows Leaking

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SX and Dog Cobra Same same
 
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