Need help - second rebuild

[Josher]

Hi All,

I'm looking for some advice... I have a '04 75hp merc 2 stroke. I had the motor rebuilt 2 years ago per the advice of a few marine mechanics as it started knocking randomly. All turned out supposedly well with the rebuild...

Fast forward two years later and my motor started knocking again! I had it taken apart and looks like one of my cylinders started scoring. I didn't catch it in time so off to get bored out and a knew piston installed. Carbs cleaned out spotless again. The engine is getting put back together this week.

I would love to prevent this from happening again! I do not know a lot about engines and I would like to ensure the guy I have rebuilding a second time is doing a good job.. I want to ask the right questions to ensure this.

Can you guys provide some insight on what could of caused one of my cylinders to run dry after one season's use after my rebuild? And what I can do to prevent this kind of misfortune from happening again? I just want to make sure the mechanic has taken the steps to ensure I'm covered and not gonna go out and have this happen a third time.

Thanks for any help!

 

[Josher]

Hi all, just wanted to follow up on this... I spoke to the mechanic and apparently there was sand in my carb. One of the cylinders was completely dry. I literally used the engine for one season after the rebuild - maybe 40 hrs max. I'm concerned this mechanic did not do a proper job... or maybe I am just completely unlucky!

Any insight? I want to ask the right questions to make sure the job goes well the second time.

Thanks

 

[gm280]

I have to ask, for real sand in the carb or was that just a saying for dirt accumulation? If real sand, then how did it get there? I'm sure you have some type fuel filter inline to filter out things like that... :noidea:

 

[Sea Rider]

What do you mean by dry, assume it's a 2 cylinder single carb engine, right ? Are both cylinder intakes clean as not to let one dispense more fuel in than the other.

Depending on mesh filter size screen, small particles as sand, dust can pass through to carb. Most internal mesh filters lets powder dust particles pass through. Will need a fuel filter with paper filter element to avoid this.

Happy Boating

 

[Josher]

Thanks for the responses. The engine is 3 cylinders. By ran dry, I mean it wasn't getting fuel/oil. Gas wasn't getting through that carb. I do have an inline filter. That's the possible cause the mechanic gave me... He thinks it may of been bad gas.

I'm just thinking for after one season, after a rebuild and my engine to malfunction like that again, there might be some other issues to look into. just want to make sure this guy is doing a good job addressing the problems considering I'm back with another rebuild after one year...

 

[huntxtrm]

could you have a crack or airleak between two of you main bearing journals? I had an evinrude lose fuel to one cylinder because of that. It was suckin air where it was not supposed to. It lost a lot of power when it happened though. Just a thought.