What kind of sealant if any on exhaust pipe to transom shield connection?

[wisebob]

Hi,
Installing new Bravo transom shield and was wondering what sealant if any would be good to put on the exhaust pipe to transom shield connection which is at the very bottom of the shield? The service manual just says to torque the 4 bolts to around 23 ft lbs and no sealant indicated; just the o-ring seal. I'd think having some sort of backup sealant would be good?

Was thinking either high-temp RTV (which color?) or possibly perfect seal?

thanks.

 

[Bondo]

Ayuh,.... A new o-ring, 'n good clean flat straight surfaces is all that's needed,....

 

[Fun Times]

While sealant isn't really needed or installed by the boat manufacturers during installation, some past forum members have mentioned that they went ahead and applied either black RTV or perfect seal successfully. If you plan to run in salt type water or let the boat sit in the water, then the added protection could be helpful but again not necessarily needed as long as everything is in good condition.

It is recommended to glue in the O-ring seal into the gimbal housing to help hold in the seal better for installation purposes.

 

[wisebob]

Thanks. I'll use black RTV I think.

My new transom shield already had the outer gasket and exhaust o-ring in place so I assume it's already glued down?

 

[alldodge]

While I do not agree with anything on a new seal, RTV is the last thing I would use on a transom seal. If you want to put RTV around the outside of the transom once the assembly has been installed, knock yourself out

 

[Rick Stephens]

I got the impression the OP was asking what to use on the o-ring that goes on the Y pipe attachment to the transom plate. I'd be inclined to use nothing there. Might use a teensy bit of copper coat or other rubber cement (even bellows cement) kind of gasket sealer if I couldn't keep the o-ring in the groove. I don't think that is even necessary as it will stay put from my experience.

Rick

 

[Fun Times]

Thanks. I'll use black RTV I think.
My new transom shield already had the outer gasket and exhaust O-ring in place so I assume it's already glued down?

If your transom assembly is brand new then there is no need to disturb any of the O-rings by applying adhesive to the backside in order to help hold it in place as that has already be done for you.

Like mentioned, nothing is really needed nor truly recommended and yours being new is even less of a true need for any added protection as there isn't any corrosion damage that sometimes randomly occurs to the Y pipe connection areas.

While black RTV sealant has been used in the past by "some", it isn't considered to be the best option available.
Here's some info covering what's liked vs not,
http://forums.iboats.com/forum/engi...utdrives/303050-y-pipe-to-gimbal-housing-seal
http://forums.iboats.com/forum/engi...rd-engines-outdrives/50260-installing-y-pipes

Should you decide on adding something for added corrosion protection then placement of the sealant should be considered as well. One member said,

I replaced the o-ring on my exhaust Y-pipe and ran a small bead of gasket maker outside of the o-ring on the mating surface. So far so good.

Another mentioned in the O-ring groove.

The transom assembly/gimbal housing goes on dry too, but some just like knowing there's added protection as you will notice in the last post, http://forums.iboats.com/forum/engi...drives/236441-mercruiser-alpha-1-transom-seal

Like most, personally I apply it dry even though I've seen/removed some black, some Perfect Seal and some sort of grease/s in years past.

Good luck with you decision.

 

[wisebob]

Fun Times,

So if you absolutely was going to use a sealant on the outer portion of the o-ring, what would you use? Hard to imagine that after all the vibration and stress the exhaust goes through, it would still remain leak free with just the o-ring.

Thanks,
bob

 

[Bondo]

Hard to imagine that after all the vibration and stress the exhaust goes through, it would still remain leak free with just the o-ring.

Ayuh,.... So long as the bolts are tightened, that joint is very rigid, 'n never moves, at All,....

 

[Rick Stephens]

Fun Times,

So if you absolutely was going to use a sealant on the outer portion of the o-ring, what would you use? Hard to imagine that after all the vibration and stress the exhaust goes through, it would still remain leak free with just the o-ring.

Thanks,
bob

The whole outdrive is that way, just orings. They do great as long as they aren't moving around.

 

[muc]

I use a light coat of perfect seal on both flanges and the bolt threads.
It's not needed to stop leaks, the oring does that. I use it because I might have to take it back apart years later.
It's used to stop corrosion. This is an area that can be awash in bilge water. Anytime a stainless steel fastener is used with aluminum you should use some type of sealant. Anytime there is a small gap between 2 flanges sealant should be used to keep the water and air out.
Perfect seal works very well for this.
I think it works better than Permatex #3
Hint: when using a new can or a can that hasn't been used for awhile, use a screwdriver to stir it up. There is a lot of thick stuff on the bottom that needs to be mixed in.

 

[Rick Stephens]

I use a light coat of perfect seal on both flanges and the bolt threads.
It's not needed to stop leaks, the oring does that. I use it because I might have to take it back apart years later.
It's used to stop corrosion. This is an area that can be awash in bilge water. Anytime a stainless steel fastener is used with aluminum you should use some type of sealant. Anytime there is a small gap between 2 flanges sealant should be used to keep the water and air out.
Perfect seal works very well for this.
I think it works better than Permatex #3
Hint: when using a new can or a can that hasn't been used for awhile, use a screwdriver to stir it up. There is a lot of thick stuff on the bottom that needs to be mixed in.

Great post. I coat every bolt in Vibra-Tite. This is not a thread locker like a hardening glue, but a super high viscosity anti seize and anti-loosen product that also prevents that layer of corrosion from electrolytic activity between the aluminum and the SS bolts. Has worked for me in all these types of applications. Love the stuff. Muc nails it though. perfect seal will accomplish the same thing.

Rick

 

[Fun Times]

Thanks again Muc
wisebob, be sure to check you private messages.

It's used to stop corrosion.
Anytime a stainless steel fastener is used with aluminum you should use some type of sealant. Anytime there is a small gap between 2 flanges sealant should be used to keep the water and air out.
Perfect seal works very well for this.

Same concept as installing a Bravo drive to the bell housing. Two aluminum parts with stainless hardware really should have grease added to the O-rings and housings used as a barrier to help prevent corrosion damage.

Either Perfect Seal or even grease would work well because you could apply it to/over the O-ring seal (like the bravo drive concept).. Use just about anything else then you really wouldn't want to apply it to the seal but just around the seal when/where possible.

The Y-pipes do have an tendency to corrode and should it corrode then like mentioned in one of the links I posted above by Don S, a better fill in type silicone "could" be used if the pipe is not in to bad of shape. If the pipe is in really bad shape then either order a new pipe or here's a video of how to repair them that's even approved by ShipShape Marine. https://www.youtube.com/watch?v=CcGpBh_Ld6g

 

[wisebob]

Thanks guys. I'm bolting on the old pipe onto the new shield this weekend. Glad I waited to do this because of the new responses. Learning something new every day. So here's a question. If you can brush perfect seal over o-rings, why not use it on all the o-rings like the drive ones too instead of 2-4-C grease? Seems like it would provide a better seal?

Thanks,
bob

 

[muc]

If you're to take it back apart in 1-2 years, grease is good enough in fresh water. I'm told some do use Perfect Seal in salt water. Even go so far as to use it on the prop shaft splines. But I've spent all my time in fresh water and it takes a lot more time to clean Perfect Seal than it does grease.