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manifolds and risers - its time
craigswardmtb
Member Posts: 1,015 ✭✭✭
We have a big trip planned in 3 weeks where we will be hitting marthas vineyard, block island, cuttyhunk, and maybe another harbor or two. The boat is running great, however I'm seeing rust on the upper and mainly lower riser gasket, and what appears to be some seepage on this furthest starboard riser. I haven't pulled the riser yet to inspect, but I suspect she may be on her way out, or at the least need new gaskets. Probably time for some preventative maintenance. I was thinking of just doing the risers at this point, but that could obviously change once I get in there. As far as I know these are original manifolds from 2005, and I know the previous owner put on taller risers due to concerns around waterline height and water ingestion, so the 6" risers were added at some point after. The boat was always kept in fresh water up until this year, however occasionally operated in salt. I'm rounding the corner 330 hours, and I suspect 100 of those hours were operation in salt. It has two merc 496 8.1 Horizon engines, so closed cooled up to the manifolds, and as far as I know was never really flushed throughout the 6 month season each year. SO what do you guys think? Did I get a good life out of these things under these circumstances? Should I consider doing the manifolds as PM at this time? The port side motor doesn't show any external indicators that have me concerned so I was thinking of leaving that one until the end of the season. Bad idea?? Any recommendations for good alternatives for risers and manifolds outside of OEM? Any snafus I should look out for when doing this job myself while in the water?
Comments
Probably due, but what I've done in the past is remove one riser & exhaust elbow (opposite on each engine) and take a good look at all 3 parts (riser, elbow, and manifold). You can only see one end of the manifold, but this should give you a decent idea of how things look. I usually took one off of each engine (usually opposite ones). & then did the other ones two years later. Make sure you have new gaskets and bolts to put back together.
Or, as you said, you could just go for the gusto. I was very suprised on my 310 how good they looked when I thought I'd be replacing them, even 4 years after that they were fine. Sometimes just putting a clean new gasket in will be all that is needed. (btw, cleaning the area before putting the gasket back in is what takes the longest)
Dream 'Inn III -- 2008 400 Express
I just did manifolds and risers....they were 10 years old. I took them out in the spring of 2009, cleaned them and put them back with new dry gaskets as per Volvo instructions....the next year they changed the instructions adding that we should use gasket sealants...
The passages were fine, minimal rust...had them cleaned out and panted the inside with Rustoleum....I needed service this year, so I figured it was time....
The mechanic thought they were in good shape, but required replacement due to the age of the metal.
I also flushed the engines with fresh water after each trip using the garden hose adaptor on each engine...
Do you have a pic where the fresh water flush adapter hooks up on the engine? I might want to install one.
well, that's good news! & yes, the turtle incident is more important.
Dream 'Inn III -- 2008 400 Express
That leaking bellows should be a high priority. A guy just finished having his boat raised at dealer's marina. Bellow failure - boat sunk -$40K in damage. MT
I'm heading to the boat tomorrow to put the riser on and bring it to my mechanic who is pulling it. They expect to have ALL bellows, shifter cables, gimble bearings on both drives replaced by Friday. They estimated $1600 for both drives.
Below are some pictures of my 6" riser block. I didn't think it looked to bad.
I'd bolt 'em right back on too. They look like they're doing fine.