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Manifold Life Expectancy

E

eselgar

New member
I have just purchased a used 3

I have just purchased a used 33' Carver that has been repowered 5 years ago with used Crusader 350 XL engines each with ~900 hours. I am thinking it would be a good idea to replace the manifolds and my mechanic has recommended this. My question is: what is a reasonable life expectancy for the manifolds in a salt water (closed fresh water cooling) environment? Is there anything else I should replace at the same time (risers)?
 
"Depends on where the raw wate

"Depends on where the raw water cooling of the exhaust starts. Where it's fresh water cooled, you're good for 15 to 20 years, but where it's salt water cooled, 5 years is pushing it.

Jeff"
 
"If I understand your question

"If I understand your question correctly, you have a freshwater-cooled closed system (heat exchanger) with raw water exhaust. Generally Crusader fresh water cooled engines will need the risers and elbows replaced at 5-6 years, given a saltwater environment, because the raw (salt) water and exhaust gasses mix at the risers. However, there is a stainless baffle that separates the raw water in the riser from the manifold; thus the manifolds rarely need to be replaced unless somehow they have gotten saltwater intrusion. In that case, you would probably be in for more extensive repairs than just the exhaust system."
 
"Eric,

I just changed my ex

"Eric,

I just changed my exhaust manifolds. FWC in salt water, 22 years old on 454's. I got a great deal on painted Osco manifolds so I did it proactively.

I probably could have gone longer but at that age they had to be nearing end of life. For $500, I viewed it as cheap insurance. Not that I'm looking to sell but you have to figure this is a great selling feature when the time comes as well.

If one of them failed mid season, that $500 would sound pretty cheap.

Bob"
 
"My exhaust manifolds are 22 y

"My exhaust manifolds are 22 yrs old and they look like new inside. Just replaced risers on one engine and removed manifolds to see conditions. So no salt in it, good for a long time. Make sure you replace the SS blocking plate with a new one

Henry G."
 
"Hi All,
Just wanted to thank

"Hi All,
Just wanted to thank everyone for their advice. turns out that the previous owner replaced manifolds, elbows and risers on the starbbord just a few years ago without much use. The end result is that I am leaving all manifolds in place and replacing the risers and elbows on port and inspecting the starboard risers and elbows. Also replasing all ss blocking plates for both enggines.."
 
"while we're on this topic

"while we're on this topic, have any of you used Osco? I've heard good things and that's what I just used.

The hardware doesn't look that great though, specifically the 12 point riser/elbow bolts. It looks like cheap/zinc plated steel. I'm thinking ahead a few years when I want to separate the two.

Anyone have any longer term results with these bolts. Is there anything I can coat them with that will hold up?

Bob"
 
"Osco is the only brand I have

"Osco is the only brand I have used (on four different boats), and no problems. The 12 point bolts are pretty much standard. When it is time to replace the risers and elbows, I don't take them apart. I just unbolt them, as an assembly, from the manifold. It is a little heavy, but easier for me than taking them out in pieces. Putting them back in is a different story."
 
Try slipping them on temporary

Try slipping them on temporary studs next time. I saw a screw driver slot in the end of the studs for removal. Holds the gasket for you as well.

Jeff
 
"Osco stuff is fine. What nee

"Osco stuff is fine. What needs help are their instructions. Make sure you do NOT assemble the gaskets dry, except for the manifold to head gasket. Use ultra copper or ultra black on the others, a wet coat with your fingers, very thin, on both sides of every gasket. On the hardware, it is ok for the 4 years the surrounding metal lasts. It still needs either paint or grease or antisieze on the heads to even last that long. And, I do antiseize the threads."
 
"Dave,

Did yours leak w/o R

"Dave,

Did yours leak w/o RTV? I did everything dry as they specified. I suppose I could see how it works next year but if I need to pull everything apart, now would be the time to do it.

Bob"
 
"Yes, assembled dry, they seep

"Yes, assembled dry, they seep saltwater out, and rust the edges. Pretty significant after the 4th year of that, requiring sandblasting of the manifold end. Not likely an issue with fresh water only use. Also, retorque all bolts after the first hot/cold cycle."
 
"Damn! Just had the riser off

"Damn! Just had the riser off one of mine and I forgot to spray paint the bare metal gasket surfaces, to see if that would stop the rusting.

From my experience, and that's mainly in fresh water, all manifold/ risers/ elbows will show rust at the gasketed joints. Why? The bare metal allows moisture to sneak under the paint, and out pops some rust. My theory is that painting the gasket surfaces MIGHT stop that.

Jeff"
 
"Jeff,
If I remember right th

"Jeff,
If I remember right the instructions that came with my elboes said to clean off the paint and do not paint the gasket surfaces. I will look around and see if I can find the paper work"
 
"Paul; that is correct, That

"Paul; that is correct, That is the instruction from Osco. No paint, no sealer. It doesn't work! I can tell you primed metal doesn't stop the water migration either. From my experiments, RTV, very thin, works quite well, and I spray prime, but do not topcoat, the mating surfaces."
 
"I had that same type of note

"I had that same type of note in the Crusader boxes for the manifolds and elbows when I replaced them. In Fact, they even added that it would void any warranty on the item IF the paint was left on when installed."
 
"Reviving an old thread here.

"Reviving an old thread here. I pulled my risers and elbows today, about half the ports were closed up and the others were also pretty corroded. I just ordered the new parts.

I had some questions related the threads above:

1) RTV? Is that Permatex RTV Silicone Adhesive?

2) Diver Dave mentioned spraying primer on the mating surfaces- what type of primer?

3) I did not pull off the Mainifolds- what's the best way to inspect them and what should I be looking for?

Thanks for the help!"
 
"I believe OSCO risers, spacer

"I believe OSCO risers, spacers, and elbows are pre-primed but need to be painted (most likely after the installation). A few years ago I replaced the risers and elbows on my 454 engines that have the log-style manifolds with the Crusader brand and they were completely pre-primed and painted in Crusader blue. Per the installation instructions I removed the paint on the mated surfaces, so I wondered why they come pre-painted in those areas if paint removal was required. It was not that easy to remove the paint and I wondered if getting the OSCOs would have been easier in the long run.

Erich"
 
Is there a reason why I should

Is there a reason why I shouldn't paint the parts until after they are installed? It just seems like it would be easier for me to do them now.
 
"No, just be careful about whi

"No, just be careful about which areas you paint. As noted previously, locations where paint is/isn't applied can drive warranty coverage.

If you are doing the metal downstream of the manifolds, you may want to make some subassemblies and then paint them. consider your engine room space as well as the handling aspects. Only one surface to mask..."
 
"What will cause a leak is a p

"What will cause a leak is a paint run. What will cause rust is a bare iron surface, even under a gasket. Zinc Chromate is a very good anti-corrosion primer, and can go on thin."
 
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