Water weeping between manifold and riser

Ryanm51981

Member
Apr 10, 2012
78
Boat Info
2006 Sea Ray 290 ----
2006 Sea Ray 38 Sundancer
Current -Ocean Yachts - 48SS
Engines
Mercury
Hey guys ,
On my port engine ( Merc 496 8.1 475 hours )
On the inboard side there is some rust and water weeping between the manifold and riser . Manifolds and risers were done in 2015 and I pulled them off to inspect and it looks like the gasket came all apart . Do these gaskets sometimes fail ?Should I just clean up the area and slap two new gaskets and a turbolator on ? The manifold from what I can see from the top looks fine .
 

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There is no need to post in multiple categories the same question. Most here use the new posts that show all posts that user has not read yet.

Also if you only have one thread all your answers and any discussion will be together in one place.

Maybe a moderator could combine them.

Good luck on your question...

MM
 
I agree that everything looks OK there.

I’d replace the gaskets with OEM parts, torque them to spec and re-torque them after a heat/cool cycle.

Keep an eye on it.
 
There is no need to post in multiple categories the same question. Most here use the new posts that show all posts that user has not read yet.

Also if you only have one thread all your answers and any discussion will be together in one place.

Maybe a moderator could combine them.

Good luck on your question...

MM
There is no need to post in multiple categories the same question. Most here use the new posts that show all posts that user has not read yet.

Also if you only have one thread all your answers and any discussion will be together in one place.

Maybe a moderator could combine them.

Good luck on your question...

MM
Sorry MonacoMike , next time I’ll just post in one forum.
 
Hey guys ,
On my port engine ( Merc 496 8.1 475 hours )
On the inboard side there is some rust and water weeping between the manifold and riser . Manifolds and risers were done in 2015 and I pulled them off to inspect and it looks like the gasket came all apart . Do these gaskets sometimes fail ?Should I just clean up the area and slap two new gaskets and a turbolator on ? The manifold from what I can see from the top looks fine .

I have the same set up and there should never be water at that gasket. That is a dry joint. study that area and you see it’s dry only. The water way is via the two elbows-up and out the exhaust. So the only way water can weep at that joint is a crack in the welding. I’ll try to explain here, the two elbows are about an inch above the joint. Inside is a chamber. Hence water sits at the bottom below the elbows. When the engine is off there remains a pool of water in the chamber. The only way out is a crack in the weld. I know because I’ve been there. Take the riser to a work bench, turn the hoses up and fill with water. Set the riser on a paper towel. Give it lots of time and you’ll find the leak.
When ordering a new riser be sure you get the right version. There are two, one tall and the other short.

Did you ever run the engine with no water like forgetting to open the petcock? Then opened the petcock.... Super heating will crack those welds when hit with cold water.

Sorry for the news.

Mark
 
Wow, the dry joint thing went right past me. Way to go.

I’ve heard that it’s easier to spot such a leak using acetone rather than water.
 
The engine did overheat once due to the belt breaking but it didn’t get super hot and was caught quickly . I have the stainless steel risers and I will re inspect them to see if there is a crack somewhere . The gasket was in really crappy condition and was like melted to the riser . My mechanic said sometimes the gaskets fail before the manifolds and Merc only guarantees the gaskets for 5 years . It was getting very pitted on the backside of the manifold facing the stern versus no water on the front side facing the bow .
 
Mine is stainless too as all 8.1S. It only takes a few seconds to super heat the stainless. Cast iron distributes heat better. There’s a crack. And as Soulshine mentioned thinner or acetone does work better than water. Most weld shops won’t touch it due to liability that your engine is at risk if their weld fails.

The tubulator part of the gasket which is also stainless, saved your engine from water intrusion. The cone shape held the water from dripping down. When you started the engine it blew the water out and dried it right up until you shut down and it began to slowly leak out again, nonetheless doing a real number on the gasket.
 
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I saved my old riser and just took this picture for you. I am pointing right at the crack. After I found the location I cleaned the soot and there it was. I hope this helps you.
 
I will offer one other thought on the gasket giving way. There’s a slim chance the rubber hose on either side was dripping down the out side of the riser and the hot gasket wicked the water inward and trapping between the riser and manifold. If that’s the case then the hose clamp was loose and the riser was not torqued tight enough allowing the hot wicking. It’s a long shot but plausible.
 
I will offer one other thought on the gasket giving way. There’s a slim chance the rubber hose on either side was dripping down the out side of the riser and the hot gasket wicked the water inward and trapping between the riser and manifold. If that’s the case then the hose clamp was loose and the riser was not torqued tight enough allowing the hot wicking. It’s a long shot but plausible.
Yes I thought about that too but your theory of the riser cracking seems like it makes more sense . Gonna inspect it next time I’m at the boat and just pick up all new manifolds and possibly a new riser and get it done . do you know off hand what size studs I need to assist it getting the manifolds on ? Saw my mechanic that worked on my old boat using studs with the head cut off to make installation easier . Also do both gasket riser and manifold go on dry ?
 
Yes I thought about that too but your theory of the riser cracking seems like it makes more sense . Gonna inspect it next time I’m at the boat and just pick up all new manifolds and possibly a new riser and get it done . do you know off hand what size studs I need to assist it getting the manifolds on ? Saw my mechanic that worked on my old boat using studs with the head cut off to make installation easier . Also do both gasket riser and manifold go on dry ?
I don’t recall the size. But take one of the manifold bolts and match the threads to make a stud. Just make sure the stud is at least an inch plus longer and the treads are only an inch or so up the stud. You just need two and save for later. If those manifolds have only seen freshwater, I bet they are just fine.

Since your on this, the hose on the front on the manifold and runs to the dripless, check that hose is clean and no rust plugging it at the dripless. This is a critical point that keeps the dripless lubed and cooled. No water flow, it will melt the dripless in minutes.
 
This is what happens when the hose plugs up and no crossover in place via the other engine. Two years ago and saved as a fail trophy on my desk.
 

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It’s been in salt for 5 seasons so I definitely think it’s time . Wow that’s crazy , I definitely will inspect that hose
 
Do you recommend using anything on the gaskets when I install them on the risers and between the manifold and engine? Also what do the manifolds and risers get torqued at ? Tried searching for a thread for the installation but cant find one.
 

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