Volvo Penta SX - water leak help

[97glastron]

Hello all,
Long time lurker but first time poster.

I own a 1997 Glastron GS205, with a VP SX (C1) outdrive. Last year, I replaced the gimbal bearing and driveshaft bellows due to a leak. If memory serves correctly, everything seemed okay when I had it out for the last time, last year.

This past weekend, I finally got around to getting it out and running again. It ran on muffs as normal, but I noticed water in the bilge almost immediately after we got out on the water. The bilge pump could outpace the leak, but I high tailed it back to the boat ramp to get it on the trailer.

I was in a bit of a rush to get it trailered and the launch was busy, so I didn't get a chance to look at it for long. It did continue to leak after shutting the engine off. I did snag a quick video though, which is here:

After going back and watching a few times, it appears the water is coming in somewhere above where the manifolds join together and exit. I felt around the manifold y pipe and did a video inspection and it looked okay.

I pulled the drive and the inside of the driveshaft bellows was dry, so I'm at a bit of a loss as to what I should check next. Is the transom plate susceptible to loosening up over time? If so, wouldn't that be obvious when pulling on the outdrive (while mounted)? I'm open to all ideas of what to check next. Thanks!

Edit to add: I did not see or feel any loose hose clamps anywhere. At one point in the video it looks like water can be seen spraying in somewhere near the transom plate.

 

[itsathepete]

The video is not sufficient to diagnose. Run it on muffs again and if it still leaks it has to be the raw water inlet. If it doesn't leak, and you already pulled the drive and found no water in the bellows, it could be the trim sender grommet or the transom plate. Back it in the water, not running, and inspect again with your phone taking video at all angles.

 

[alldodge]

Looks like the exhaust Y pipe

 

[97glastron]

Thanks for the responses. I checked all of the hoses that I could see/feel and the ends all felt fine and clamps were tight.

The exhaust y pipe appears to be okay when I took a video of the areas I couldn't physically see.

Do transom leaks (from a rotten transom) usually show up towards the bottom of the transom plate, rather than further up like my leak seems to be?

My next move will be to reinstall the drive and back it into water while keeping it on the trailer. Hopefully I can then spot exactly where the water is coming in. I've gotten it down to about a 30 minute job to remove/install the drive.

 

[Scott Danforth]

need to pull the motor to look at the y-pipe

could also be steering pivot, or it could be bad transom

 

[97glastron]

Update: it is looking like the transom is the issue. I took it to the launch tonight and could see water slowly pouring in from behind what appears to be the bottom of the transom plate.

When I got home, I filled the bilge up more with the hose. Water did not leak, but when I lifted UP on the outdrive, water started coming out. I took a video of that (the best that I could) below. The leak can be best seen around the 22 second mark.

I've read about some people using adhesive to seal around the transom plate, but that seems to be a temporary fix at best, and a way to create more problems at worst. The boat is a 97 with an otherwise decent looking hull and a good power train (I think, it's a 5.7 and VP in a 20' open bow). What are everyone's thoughts on going through with a transom replacement? I paid something like $4K for it about 3 years ago. I am still weighing the options.

 

[Scott Danforth]

if you love the boat, fix it. its not that hard.

everything you need to know to fix it right is in the hull restoration stickies.

 

[BRICH1260]

You might get lucky and just have a bad transom plate seal rather than a flexing, rotten transom. Sealant might get you through the season but should not be permanent. You need to see if the seal is bad or if the transom is rotten.

 

[Lou C]

Only other thing you can try is
If you can access the nuts that hold the inner & outer transom together and tighten them you MIGHT get lucky. Worth a shot!
If not then you have a big job, but it beats buying another used boat

 

[97glastron]

Only other thing you can try is
If you can access the nuts that hold the inner & outer transom together and tighten them you MIGHT get lucky. Worth a shot!
If not then you have a big job, but it beats buying another used boat

Interesting you mention that. I actually went out this morning and did just that! It looks like those are supposed to be torqued down fairly tight according to the specs I found online.

The two bottom nuts were definitely on the looser side, though not hand loose or anything. Before tightening, I could see a small amount of separation between the drive and the transom when lifting the drive.

After tightening, I can no longer see any separation when lifting the drive. I'm not really sure what to make of this though, as my understanding is that those bolts don't typically just loosen up (unless the wood in between is softening and or rotting). The only explanation I can think of would be if the drive took a hit sometime before I owned it, but I'd think it'd need to be a heck of a hit and in that case the transom may have been damaged anyway.

I might drill a couple of holes to verify the condition of the wood, but I'm leaning towards filling up the bilge to see if that fixed the leak. If it did, then I may drill holes. I'm having a little bit of a difficult time with the hammer test, since the hammer does bounce near the drive, but not quite as much as it does closer to the lower corners of the transom. I'm not sure if that's due to the geometry of the corners just causing more bounce.

 

[Lou C]

Check it again & report back

 

[alldodge]

Transom nuts don't back off on there own, your transom is shrinking

 

[Scott Danforth]

as my understanding is that those bolts don't typically just loosen up (unless the wood in between is softening and or rotting).

This