2001 Merc 6.2L MX reversion?
 

Howdy all. I'm working on my 2001 Dancer 310 cruiser with twin 6.2L engines w/ bravo III's. I noticed on port engine, the riser gasket was leaking externally; so I purchased new OE exhaust components and gaskets for the engine. When i pulled the first manifold/riser apart, it was apparent the gaskets were leaking both internally and externally. The other manifold/riser on the engine did not have an obvious gasket issue. However, traces of water was found at the bottom center of the manifold, and it had been infultrating the exhaust valves. No water in the oil however. I decided to pull the spark plugs, and the center plug on the side with no apparent issues was rusty. Not good. I did a compression check, and found that cylinder was 10% lower than the highest on that engine. I inspected the manifold and riser with a flashlight to check for cracks in the cooling jackets; non found. I don't believe there to be a head gasket issue, otherwise it wouldn't make compression. A leak down check indicates exhaust valve leakage, but this engine has not been ran since last October.

The stock set up on this has an extra 3" riser block before the elbow. Exhaust flappers were also intact; though i'm replacing with new regardless. I'm concerned i don't know where the water came from on that side that had no gasket failure. I'm wondering if this has been reverting a little water at idle. I'm not sure, this is my 2nd season with the boat.

The other engine, also has original exhaust, no visible signs of leaks. I decided to pull a center spark plug, and found it rusty with a drop of water on the end. I now ordered new exhaust to be installed on that engine.

Any further thoughts on this? I figured i need to start with replacing the 20yr old exhaust system and flappers before i can jump to a conclusion of reversion. I don't believe head gasket failure would be on both engines affecting same cylinders, with good compression numbers.

Thoughts?

Thanks for the help.

Wet joint, or dry joint risers?

wet

The 6.2's arent really known to revert. With wet joint risers and the spacers, meaning double the gaskets, double the trouble, they were/are probably leaking a bit when expanding and contracting. The other thing is, depending on which plumbing routing system you have, there is a reasonable possibility of condensation being a factor, and even while being stored, unless in temp controlled environment, condensation can still occur

Yeah, i guess i'm giving the big hammer approach with new exhaust and new gaskets for each engine. They are 22 yrs old after all. I guess i'm unaware of just how much condensation can be in these manifolds after sitting all winter...... I was hoping my winterization process of pulling the fuel input line and rigging to suck off a gas can mixed with fuel additive and 2-stroke oil would have coated some of the components to help against the rust issue if there was condensation on it all winter. Must not have mixed it up heavy enough.

Sure would be hnice to inject fogging oil in to the intake like the carbed engines. Not sure if this motor has a MAF sensor that could get ruined if this is done. I know on my 502 mpi, there was a merc SB that said not to inject fogging spray. Had to do it the fuel pick up way. Perhaps next time, i'll dump the fuel filter and fill with my mixture as well. I didn't do that last time.

No MAF.

So why not fog through normal means vs pulling in a 2-stroke mixture up through the fuel pick up? What sensors can get ruined with direct fogging?

https://cimg5.ibsrv.net/gimg/www.off...6a6da1f77.jpeg

Head gasket
 

Looks like I have a head gasket failing on my Stbd engine. Middle two cylinders 40psi less than the rest. Leak down shows leakage to the cylinder next to it.

how much vertical clearance is required to pull the distributor out? The back 20% of this 6.2l is under the deck. I have about 5” right now with the cap and wires still installed.

I found this picture online. No real reference for the bottom of the distributor. If i interpolate the picture, i'd say the distributor will need to come up 7" to clear to be removed.

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