Dry vs. Wet seal manifolds and risers

[CurrentObsession]

I have been looking at various websites for replacement exhaust manifolds and risers for my 1999 5.7 liter 250HP engine

(Serial # 0L319872)

What is the deal with dry vs wet seals?

Thanks

 

[Bondo]

Re: Dry vs. Wet seal manifolds and risers

I have been looking at various websites for replacement exhaust manifolds and risers for my 1999 5.7 liter 250HP engine

(Serial # 0L319872)

What is the deal with dry vs wet seals?

Thanks

Ayuh,... It's got Nothing to do with Seals...

The newer dry-Joint exhaust, has No water passages at the manifold to riser joint...
They still use a gasket to seal the exhaust, but there's No water there to leak into the motor...

 

[tpenfield]

Re: Dry vs. Wet seal manifolds and risers

Just to elaborate on what Bond-o said . . .

The design was changed to separate the interfaces of the exhaust and water, so that they cannot meet at the joint. There are now 3 mating surfaces instead of the traditional 1 mating surface - 2 for the water and 1 for the exhaust. If either of the water joints leak, it leaks to the outside world, not into the exhaust.

I am not sure all models of Mercruisers have the dry joint system available, but if you can get one for your engine, go for it.

 

[HT32BSX115]

Re: Dry vs. Wet seal manifolds and risers

Just to elaborate on what Bond-o said . . .

The design was changed to separate the interfaces of the exhaust and water, so that they cannot meet at the joint. There are now 3 mating surfaces instead of the traditional 1 mating surface - 2 for the water and 1 for the exhaust. If either of the water joints leak, it leaks to the outside world, not into the exhaust.

I am not sure all models of Mercruisers have the dry joint system available, but if you can get one for your engine, go for it.

Ted, so far I haven't found "Dryjoint" manifolds/risers for the 454. Have you? I am guessing that no one makes them yet (if ever)

 

[tpenfield]

Re: Dry vs. Wet seal manifolds and risers

Ted, so far I haven't found "Dryjoint" manifolds/risers for the 454. Have you? I am guessing that no one makes them yet (if ever)

No, I had to get the traditional ones I could not find any for the 454, but I think the 5.7 has them available. Mercruiser may not make them since the 454 is E.O.L. (end of life)

I just bought a set of Barr brand and installed them last night.

 

[CurrentObsession]

Re: Dry vs. Wet seal manifolds and risers

Okay....but how would my current system (wet) get converted?

I have never looked that closely at how it is plumbed but I assume with the current set up, water enters the manifold/riser system from the bottom of the manifold then goes up and exits somewhere towards the end of the riser and gets mixed with the exhaust gases and then down and out at the prop.

How does that happen with the dry system? Perhaps cross-section drawings would be helpful, anybody have a link?

 

[Don S]

Re: Dry vs. Wet seal manifolds and risers

Here is a link to manual #31. It's not for your engine (it's for newer), but it does show the wet and dry joint exhaust systems.
Study sections 7 (Exhaust) and 10 (Flow diagrams) and I think you will have a better understanding of the two types.

http://www.4shared.com/document/UA6kxFEY/Service_Manual_31.html

 

[achris]

Re: Dry vs. Wet seal manifolds and risers

You would need to change the manifold and elbow, and that's all.... Just be aware that the first dry-joint elbows were the same down angle as the older 'wet' joint.... A couple of years later Merc increased the angle (to about 15 degrees) and the height by 1.7". If you get the later ones, you'd also need to change the first tube after the elbow.... So, get the earlier dry joint elbows, with the manifolds, and bolt them straight on..... Don't forget the new gaskets too....

 

[CurrentObsession]

Re: Dry vs. Wet seal manifolds and risers

Fantastic info....thanks!