Manifold assesssment

[Shaun77]

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Finally pulled my manifolds and risers off. The risers were easy enough to see they were pretty bad. My question is with the manifold and spacer shown(the other manifold looks identical really). The water ports don't look to bad to me but this is the first pair i've seen. So how do they look? Can they be cleaned up? What about the inside passages I can't see?

 

[fwebster]

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"The water ports don't look to bad to me……………"

Just so all the bases are covered there, it is a fallacy that the manifolds and risers fail in the water jackets. What actually happens is that air from very near the water travels up into the exhaust system and the castings fail from the exhaust side in, rather than the water side out. I can't see up in the exhaust port or down the runners well enough in the photos to comment, but look for flaking rust in the exhaust side. Some slight powdery surface rust is normal but flakes of rusty cast iron coming loose is a red flag.

Given the year of your boat and the guess that you keep it on a trailer, on a lift or dry stacked, you probably have several years of life left on your castings. Typically we see about 5 years on new Mercruiser risers and manifolds in the NW Gulf coast area.

 

[Shaun77]

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Interesting point. Did not know that. Heres a better look. Is that the flaking as you described?

 

[fwebster]

Since you already have them off the boat and are this far into their useful life, I think I would replace them.

The other point I didn't mention is that the gaskets between the manifold, spacer elbow are a frequent source of leaks so replacing the castings and new gaskets starts your manifold riser clock over again. You might get another year out of these, but you would need to pull them off and check them every 12 months from here on.

I know it is your money I'm spending, but if it were mine, I'd get it over with and enjoy boating without the constant fear than the next time you go out you may find an engine full of seawater.

 

[Lazy Daze]

I don't really see anything that says "Oh my gosh, you better replace them NOW". I wouldn't be surprised if you got at least a few more years out them. But on the flip side, if this is something you're going to have on your mind every time you're out boating, well, there are worse things that one can do than replace parts a little early.

 

[fwebster]

Dennis……..

Look at his location. If a riser or manifold gets a leak he fills an engine full of salt water and that is not usually a repairable event.

 

[dpmulvey]

Do people "boil" their manifolds and risers anymore? Yes I know I'm showing my age.

 

[fwebster]

There is a radiator shop here that does when asked to. That may clean up some pod the rust and scaling, but the problem is you still don't know how much casting wall thickness is left.

 

[Shaun77]

Gonna go ahead and replace it all then. I couldn't believe the price of the 1.7" spacers ,$450 alone! 2 more questions tho. The kits I'm looking at don't come with the pipings and fittings, should those be replaced as well or can I use the old ones? Lastly, when applying the gasket sealant, should it be applied only to the water side or to the entire gasket surface? I've seen it done both ways.

 

[Strecker25]

Gonna go ahead and replace it all then. I couldn't believe the price of the 1.7" spacers ,$450 alone! 2 more questions tho. The kits I'm looking at don't come with the pipings and fittings, should those be replaced as well or can I use the old ones? Lastly, when applying the gasket sealant, should it be applied only to the water side or to the entire gasket surface? I've seen it done both ways.

May I ask where you got that price? Seems steep for the spacers. I've been shopping for manifolds/risers/elbows pretty rigorously to find the best price and have narrowed it down to about 1900 shipped for my twin 5.7s using all merc parts

 

[Shaun77]

It was fixmymercruiser.com. It was kind of a one stop shop as they had both the manifold/riser kit and the spacer kit. The $450 is for both sides tho. I've found them elsewhere but not for much cheaper.

 

[Strecker25]

It was fixmymercruiser.com. It was kind of a one stop shop as they had both the manifold/riser kit and the spacer kit. The $450 is for both sides tho. I've found them elsewhere but not for much cheaper.

Im using the same site actually. I didn't realize you were the newer dry joint, that stuff is expensive!