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A few questions on repowering

A

ancopre

New member
"I finally decided to repower,

"I finally decided to repower, that’s the easy part. I have 2000 twin mercruser 350 mpi with 1500 hr. Both engines have been wet before, both have had valve jobs done on them at least once. Both have had complete exhaust manifolds, spacers and risers replaced 3 times. Two times with Mercruser and once with Osco. Osco the last time, infact 20 hrs. ago.
Now for my problem, the port engine has so much salt deposit on the new plugs that you can hardly see the contacts. And that is on both sides of the engine. Buy the way the engines are what they call a half system fresh water to the engine and salt water through the manifolds.
Is it possible the osco risers are sucking water back through the exhaust outlet? Oh I forget to tell you I also installed a Perco flush valve in line after the sea strainers. Where can the water be coming from. Is it the engine, manifolds or maybe the muffler system. nothing has been changed since 2000 when the boat was new. I have ZF 630A tranis, would it be wise to replace the engines (I’m thinking Crusaders) and using my old tranis. Any advice on the Crusaders any better than Mercrusers? Thanks in advance, this is a great forum."
 
"i would be suspect of water c

"i would be suspect of water coming in from your
intake manifold sounds like you have a high rate of corrosion in your boat and i would not be suprised to find the intake has corroded from thermostat area into intake runners, good luck."
 
Dave:

Are you sure it's

Dave:

Are you sure it's salt and not fuel additive residue that has fouled the plugs? Octane enhancers and other OFF THE WALL ADDITIVES made by BUBBA INC. will foul plugs in just a few hours.
 
"I did use marvel mystery oil

"I did use marvel mystery oil in the fuel thinking it would clean the injectord, but now i have 1 low cylinder (100 psi all others are 175- 185)
thanks again"
 
Is that a dry reading? Try a

Is that a dry reading? Try a wet reading w/1 tbls. of engine oil. If it remains the same the valves are the problem--could be a buildup of carbon. Try Mercs'. carbon remover. If it goes up the rings are worn.
 
I'me going to repower anyw

I'me going to repower anyway. I just want to be sure the engine is at fault not any thing else like the cooling water coming in. Is it possible that on the power stroke of the bad cylinder it is sucking water back into the engine? Remember the manifolds are salt water cooled. Also how about the Crusaders fresh water cooled? Any better than Mercusers?
 
"When you repower, get the ful

"When you repower, get the full fresh water cooled system that includes the manifolds and risers."
 
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