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smoking 260

901 Views 10 Replies 5 Participants Last post by  Mkos1980
ok, i got my boat out and it runs fine. But it is smoking. it doesnt smell like its oil related, it looks and smells like exhaust does when its a cold day.....you can see your exhaust. anyone have any clue what would cause this? i have check the pressure on all cylinders, all are good. oil was just changed and looks great, not milky at all. everything is tight. boat runs fine just when i get on it, it smokes. when i let off the throttle, it will smoke for about a minute then stops. doesnt smoke at all during idle. im lost any ideas? its a 1985 mercruiser 260. 5.7 thanks.

Think it might be water in the fuel? moister in the exhaust?
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my old Nova steamed a lot, I think the water may be restricted in the manifolds and boiling, how old is the exhaust.
Mine does that by choice - I run my exhaust almost dry
so I get alot of steam.
It might just be steam. could be you need a new impellar in the water pump. could be that you have a blocked water passage causing the exhaust to run hotter than normal.
im pretty sure its the original exhaust. thats what i was thinking...steam. how would i remedy this? new exhaust? i will put a new impellar in it before i take it out again. see if that fixes it.
put a new impeller in it, and it still steams... how would i check to see if the exhaust was blocked? Thanks. also how much would replacement manifolds be?
How much raw water is coming out of the exhaust tips?
not for sure the exact amount but a pretty good bit. is just as much as last year when it wasnt steaming. it stays cool. like i said everything runs fine. the right side seems to have less water coming out, but both sides steam. any ideas?
Mine always steams during take off and after a hard run. Give it a minute or so and it stops.
If those are the original manifolds I would think about changing them. How do your plugs look? If they are super clean you may be getting some reversion. I had some intake valves ruined by bad manifolds on my Scarab 1. If you run in fresh water get some aluminum ones. Those old iron manifolds weigh a lot. Mine does not steam much unless the water is cold.
any particular brand that you recommend? Im not looking for performance. i just want to enjoy the boat and not have to worry about anything. is there a what to take the old ones off and have them cleaned out? or just trash them and get a new pair? Just looking for the easiest way to get it fixed.
Trash them. If your looking for a good replacement be it cast or aluminum, Sierras and Osco's are good. For aluminum ones the GLM are good.
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