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Mercruiser 454 fuel injected raw water cooled iddling rough issue

1

14020boat

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"about to purchase a 98 sea ra

"about to purchase a 98 sea ray 37' with rebuilt 454 mercs, i had the engine compression checked and it checked out well, ran the boat and it ran ok, port engine didnt seem to have the same power the starboard engine had. also at start up and idle it sounds as if there is a slight knock that continues.
it just doesnt sound as good as an engine should sound. reving engine gets up to just under 4000 rpm.
my question is , what could cause this noise or miss, since the engine compression is fine, and it ran ok, no stalling or issues like that, it starts right up? could this be dirty distrubuter? bad fuel injectors? bad computer?
if the compression is good, and boat ran ok, what could this be. also the engine oil was clean and the way it should look, when compression was done all the plugs were replaced, air clearners cleaned and it still sounded the same.
any recomendations? or help would be appreciated."
 
"Mark,
Well what can I say,

"Mark,
Well what can I say, but I have the same issue.I ran mine over 70hrs last year and runs great,compession ok.Has that slight knock at idle which I first thought was a clogged lifter.Then was thinking the rockers needed adjusted. Everyone I spoke to about this tells me to let it go...it isn't anything to worry about and some of these big blocks will do this....Todd"
 
"You are making a big investme

"You are making a big investment; is the engine under a warranty? Yes? Then don't buy it unless they fix it. Todd is telling you his experience with that engine but for me, before buying the boat, the engine would be to my satisfaction."
 
"Gus is absolutely correct.Mar

"Gus is absolutely correct.Mark had a lot of questions flying there and I was trying to give him other things to think about and may be his noise.Like Gus said more or less-nows your chance,that if they want to sell the boat they should have this checked out.If they refuse...back to the money table.Not as many boats sold these days,doubt they will want to lose a sale.Just my opinion here.By the way, I still lean towards a valve train noise...Todd"
 
"Mark...
"my question is

"Mark...
"my question is , what could cause this noise or miss, since the engine compression is fine, and it ran ok, no stalling or issues like that, it starts right up?"

Lots of places in an engine that can cause noise and won't affect the running quality or compression. Doesn't meen it's nothing to worry about.

- main bearings on crankshaft wearing
- conn rod bearings wearing (double click sound)
- small end hole of conn rod elongating (double click sound)
- piston slap
- valve train problems, lifters, spings

How is the oil pressure - that will give some indication to bearing status.

Wrench"
 
I dont mind a miss or two in a

I dont mind a miss or two in an engine and a tick and perhaps a rattle but I am alergic to knocks.
See if you can grab someone who is well experianced in the querky little noises a 454 can make and let them have a listen.
Better to safe than poor (I mean sorry)
Cheers
Peter C
 
"If possible, have an oil anal

"If possible, have an oil analysis done. This may help you determine if there is an issue, and what it may be.

Dave"
 
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