Exhaust manifold/risers/elbow question

[badrano]

I've been digging around the forum to what info there is regarding how long manifolds last in non-fresh water environments.

I've got a 2005 Chap 256SSi with the MX 6.2 MPI s/n 0W061713, Bravo 3. I've owned the boat going on 6 years and bought it with 160 some hrs on it. It was a fresh water boat and I mainly boat in brackish water. It's trailered and I haven't been consistent on flushing it after every use. Based on what I've read, I think I'm pushing the limit to where I need to start thinking (and saving $$) about replacing the manifolds and such. I have not had any cooling issues up to this point.

I've also read that I could start off with popping the elbows off to inspect the water passages. I'm assuming if I pop off the elbows, I will need to replace the gaskets. Can I re-use the bolts? I've read things where these bolts could become elongated if torqued down too many times. I've seen pictures of what the rust build up would look like, but I just learned that those pics were of wet joint elbows/manifolds. I have dry joint with 3in risers, so would I expect to see similar rust build up?

Any advice/suggestions? Probably more questions to follow.

 

[alldodge]

Guessing your open (raw water) cooling and not closed, correct?

Bolts can be reused provided they are fully intact and have not been reduced by rust. If bolts are over torqued they can be compromised, but assuming your motor has not been touched they should be fine

Yes have a look at elbows and do replace gaskets

 

[Lou C]

I would figure on using a thread chaser, solvent and compressed air to make sure the bolt holes are clean, or else you might not get adequate clamping force on the gasket. Merc's dry joint is a lot better about keeping water out of the exhaust than the older style wet joint though.

 

[Chris1956]

Pull the rubber sleeves off the risers and look at the place where the cooling water mixes with the exhaust. They tend to rot/rust out there first, in my experience.

In full salt water, risers/mannys tend to last 8 years of so. If you do remove the risers from the manifolds, clean up the mating surfaces with sandpaper on a glass plate. Also, be sure to use the silver Mercruiser gaskets. The thinner paper gaskets often fail