Exhaust housing gasket?

[Gh0sticles]

Hi, I have a 2003 6hp Johnson 4stroke Outboard, model J6R4STS. I pulled he exhaust housing / midsection to service the pivot tube and the lower unit. Now I’m ready to button it back up but I’m at a standstill since I don’t know if I’m supposed to use some type of adhesive or liquid gasket to seal the exhaust housing to the oil sump.. or to seal the lower unit to the exhaust housing.. need some guidance please.

 

[Gh0sticles]

Anybody? I’m thinking there might have been a thin liquid sealant from the factory to keep the exhaust from leaking out or water from leaking in.. it’s hard to tell though

 

[F_R]

Anybody? I’m thinking there might have been a thin liquid sealant from the factory to keep the exhaust from leaking out or water from leaking in.. it’s hard to tell though

I just don't know the answer. But some kind of sealant surely won't hurt. What kind? I don't know

 

[scatgo]

I used high temp RVT. So far everything is good. Just follow the directions on the back of the tube and all should be well.

 

[Gh0sticles]

10-4, thanks for this feedback. I’ll probably do the same but I wonder how much it really matters. I think there’s a weep hole passage right at the front of the gear case to allow water / unburnt oil to escape. I couldn’t find any re-assembly instructions in the FSM

 

[scatgo]

Do you know if your engine has a exhaust relief port on the back or the engine?Looking at the picture you posted there is a black plastic cover on the back of the engine. With the engine running dose exhaust and water come out of that black cover?

 

[Gh0sticles]

Do you know if your engine has a exhaust relief port on the back or the engine?Looking at the picture you posted there is a black plastic cover on the back of the engine. With the engine running dose exhaust and water come out of that black cover?

It does have this port. But if I’m honest, I never paid it much attention so I can’t be certain if water comes out. There’s certainly evidence that some exhaust comes out though. Can you please explain it’s purpose?

 

[scatgo]

On my engine it is called a exhaust relief. What is dose is allow exhaust pressure and some cooling water out of the engine when the exhaust pressure is not high enough to push any water out of the prop. If you did not use a sealant on the lower unit the water level would be higher that it should in the exhaust housing and may need higher exhaust pressure to push the water out. I am not sure what the result would be but i am sure it would not be good.

 

[Gh0sticles]

On my engine it is called a exhaust relief. What is dose is allow exhaust pressure and some cooling water out of the engine when the exhaust pressure is not high enough to push any water out of the prop. If you did not use a sealant on the lower unit the water level would be higher that it should in the exhaust housing and may need higher exhaust pressure to push the water out. I am not sure what the result would be but i am sure it would not be good.

I bet I’m just overthinking things, as usual. The LU is completely submerged usually so I don’t really understand why water inside the exhaust housing would be an issue. The exhaust passage will certainly allow water to enter up to the water line, right? And my weep holes aren’t intended to be clogged.. so I’m thinking maybe it wouldn’t really do much if I did apply a sealant.. other than making it more difficult to service in the future

 

[scatgo]

I agree 100%. But do we know if it will affect performance if you have exhaust leaks?

 

[Gh0sticles]

Good point