Accidentally left off water passage seal...

[brajgreg]

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7749307-44-10670.aspx

Replaced my gimbal bearing and bellows over the weekend as well as some other general maintenance on a Volvo Penta dp-sm 1.95 outdrive. When reassembling I didn't realize it, but I left off the water passage seal (part number 81 in the link above). I ran the boat for a bit yesterday and it ran great. How important is that seal? I'm not even sure what it's supposed to do... It goes around the water pickup hose so you're pulling specifically from the holes at the bottom of the drive when it's installed. If it's not installed, you're pulling in from around the hose (a bit, maybe) as well as from the normal holes in the drive.

I can obviously remove the drive and fix it, but my boat stays in a lift behind my house. If it was already trailered--no problem. But having to trailer it, pull the drive, and install the seal is kind of a PITA, and it didn't seem to affect anything yesterday. I'm mainly just wondering what the thing even does, and how important it really is...

Thanks!

 

[dypcdiver]

This "O" ring is to seal the Outdrive leg to the pivot housing on the cooling water side. If your outdrive is in very good condition it might create a parcial metal to metal seal. However the chances are that as soon as you get the boat up on the plane and that part is out of the water it will suck air without the "O" ring and you will overheat the engine.

 

[Lou C]

You need to replace that seal because when the boats up on plane that area is out of the water and it will suck in air between the drive & the pivot housing. The same thing can happen if that plastic water nipple (# 13) cracks. I have the same gasket on my OMC Cobra and just put some OMC triple guard grease in the groove where it fits to hold it in place while installing the drive....

 

[brajgreg]

Thank you, both, for your resposnes. I wasn't thinking about it being up on plane--I was imagining it being submerged all the time, and that it would barely be sucking up water through here, and just couldn't figure out why it mattered... This makes sense, though.

I actually went ahead and fixed it last night by dragging someone's floating dock behind my boat, barely pulling the drive off, putting the seal in, and closing it back up. Took a couple hours, and is a PITA for just one little seal, but my thought was they didn't just design and install that seal for no reason.

Thanks again for your input.

 

[Lou C]

You know that V/P just copied OMC's transom mount design that's why I am familiar with the Volvo even never having owned one. However, one difference:
the Cobra uses a gasket between the drive and pivot housing, the V/P does not because the different shift linkage design meant they did not have to keep water out of the same areas. BUT, the gasket when installed with OMC gasket sealer on both sides, prevents the drive from corroding onto the pivot housing esp in brackish or salt water. On the V/P you can get corrosion between the 2 housings and it can corrode on, esp if not removed each year. So, I advise coating the mating surfaces of the upper gear housing and pivot housing with OMC/Evinrude triple guard grease, it is an excellent water proof grease that will prevent those parts from corroding together.....