Water leak at the transom

csrb7007

Cadet
Joined
Jan 20, 2023
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6
Hello all, first time posting on this forum, and actually, it's my first time owning a boat. That said, I've operated and maintained CG boats for a long time and also was a marine inspector. That said, it did not prepare me for boat ownership. I now have a 2005 Four Winns Vista 348 with twin 5.7 Volvo Pentas with DPSM outdrives. The boat has been in fresh water in Tennessee until I bought it and moved it to the Potomac last summer. During the marine survey, we discovered a small amount of water leaking into the bilge from the transom cutouts at both Y-pipes. During the boat haul-out, the surveyor checked the transom for any signs of saturation, rot, or delamination but everything checked out well, on the inside of the transom and outside. I am now having a hard time getting a straight answer out of any of the local VP shops. I am reluctant remove and maintenance both outdrives, put the boat back in the water, only to find the maintenance did not fix the leak. Is there any way, short of removing the complete stern drive, to ascertain where the transom seal is defective?

Thank you for any suggestions you may have.

Rich
 

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Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
Pull boat
Pull drives
Pull motors
Look at the problem with your own eyes

May be an o-ring at the y-pipe
May be corrosion
May be rot
 

alldodge

Supreme Mariner
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Mar 8, 2009
Messages
37,564
Drive has to be pulled to even start to get an idea. If nothing is found the motor is next
 

Lou C

Supreme Mariner
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Nov 10, 2002
Messages
10,502
Agreed while the engines look amazingly clean for their age you need to pull the drives to check the driveshaft bellows for leaks. That would be the easiest solution to your problem. Keep in mind as clean as they are these engines are now 18 years old. It could be the bellows; transom seal or the oring seal for the exhaust Y pipe.
If you do have to pull the engines & transom assemblies once it’s fixed you’ll be good for a long time.
 

csrb7007

Cadet
Joined
Jan 20, 2023
Messages
6
Pull boat
Pull drives
Pull motors
Look at the problem with your own eyes

May be an o-ring at the y-pipe
May be corrosion
May be rot
Thanks Scott, the boat is sitting on blocks, will be pulling the drives, hope not to be pulling the engines. Time will tell.
 

csrb7007

Cadet
Joined
Jan 20, 2023
Messages
6
Agreed while the engines look amazingly clean for their age you need to pull the drives to check the driveshaft bellows for leaks. That would be the easiest solution to your problem. Keep in mind as clean as they are these engines are now 18 years old. It could be the bellows; transom seal or the oring seal for the exhaust Y pipe.
If you do have to pull the engines & transom assemblies once it’s fixed you’ll be good for a long time.
Thanks Lou. In regard to the engines looking clean, they really do look good.
 

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Lou C

Supreme Mariner
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Nov 10, 2002
Messages
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I'm in a salt water area and have moored my boat for 20 years here and they would never look that good. So once you go this problem squared away you'll be good for a long time. Four Winns builds a nice boat. Here's my old '88 on the mooring.
1988 FW on the mooring.JPG
 

QBhoy

Admiral
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Mar 10, 2016
Messages
7,176
I’d take a guess at the most common place for a VP drive to leak (of the usual models historically), would be at the steering pin. Not always obvious, but certainly a culprit and first assumption for me.
 

csrb7007

Cadet
Joined
Jan 20, 2023
Messages
6
I'm in a salt water area and have moored my boat for 20 years here and they would never look that good. So once you go this problem squared away you'll be good for a long time. Four Winns builds a nice boat. Here's my old '88 on the mooring.
View attachment 374744
Nice boat Lou.
I’ve turned wrenches most of my life and I’m going pull the drives myself. Before I do, I’d like to pick up a service manual. Do you have any recommendations?
 

csrb7007

Cadet
Joined
Jan 20, 2023
Messages
6
I’d take a guess at the most common place for a VP drive to leak (of the usual models historically), would be at the steering pin. Not always obvious, but certainly a culprit and first assumption for me.
Tanks, I'll surely take a look at that.
 

Lou C

Supreme Mariner
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Nov 10, 2002
Messages
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Here’s what I’d do.
If the boat is out of the water run them on the water hose and watch that spot carefully. If you get water there it’s likely that the rubber oring seal between the exhaust Y pipe & the transom mount. That might rule out the bellows & transom seal. If not & it only leaks while sitting in the water then you’re back to bellows or transom seal. If it’s the bellows that’s the easiest by far repair, about 2-3 hrs per engine but you may have to replace the gimble & ujoints. The bellows on the VP SX series last about 10 seasons.
 

csrb7007

Cadet
Joined
Jan 20, 2023
Messages
6
Here’s what I’d do.
If the boat is out of the water run them on the water hose and watch that spot carefully. If you get water there it’s likely that the rubber oring seal between the exhaust Y pipe & the transom mount. That might rule out the bellows & transom seal. If not & it only leaks while sitting in the water then you’re back to bellows or transom seal. If it’s the bellows that’s the easiest by far repair, about 2-3 hrs per engine but you may have to replace the gimble & ujoints. The bellows on the VP SX series last about 10 seasons.
Great idea Lou, I‘ll definitely give that one a try. I do know that it leaks while sitting in the water which, in my simple way of looking at it, leads me to believe it is either the bellows or transom seal.
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
Thanks Scott, the boat is sitting on blocks, will be pulling the drives, hope not to be pulling the engines. Time will tell.
if you have to do any work to the y-pipe, you have to pull the motor.

pulling the drives is half the work of pulling the motors
 

HiWard

Recruit
Joined
Sep 20, 2022
Messages
2
I have a similar issue with my VP 5.7 and DPSM drive, but mine apparently only leaks when the engine has been run. Pulled the drive last fall and the bellows was dry. I therefore suspect a leaky seal between the y-pipe and the transom assembly, but have yet to confirm this (boat is currently on land). Is there any way to tighten the four bolts on the y-pipe without pulling the engine?
 

Lou C

Supreme Mariner
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Nov 10, 2002
Messages
10,502
It depends on the boat and the installation, some have been able to do it, you may need a crowfoot wrench or an offset box ratching wrench, to reach them.
 

HiWard

Recruit
Joined
Sep 20, 2022
Messages
2
It depends on the boat and the installation, some have been able to do it, you may need a crowfoot wrench or an offset box ratching wrench, to reach them.
That’s a great suggestion, hadn’t thought about that. Thank you!

Would anyone, by chance, know the dimension of the bolt heads?
 
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