older inline-six cylinder failure

[monk-monk]

Hello Friends, it's been a while since i've talked with the outstanding people here on iboats! I have a question about the older inline six's and what I hear people "say" when selling parts from motors that no longer run. Over and over again I hear...selling this or that because it "lost" a cylinder. The reason I ask this question is to "prevent" (if this is possible) happening to my motor! What is the main, or common cause of cylinder failure in these motors? If theres one thing i know about two-cycle engines it is the fact that the fuel mix ratio MUST be right, and the fuel delivery to each cylinder has to be accurate...could poor fuel system maintenance possibly be the leading problem? Another observation is that it always seems to be the number 1 cylinder...Lets talk about this...

 

[thefairlaneman]

Re: older inline-six cylinder failure

My 61 evinrude lost a cylinder when the piston rubbed a deep gash into the cylinder wall. A bad or lost cylinder will show up in the pressure test.Often the cylinder thats more subject to heat or internal water leaks will be the first to go bad. One of the old school guys who really know their stuff can add to my ideas for sure.

 

[Chris1956]

Re: older inline-six cylinder failure

Monk-Monk, The inlie sixes are prone to lose cylinder 3 and then cylinder 1 due to overheat, too much spark advance or lean mixture. If you are really "lucky" you can lose both at the same time....

Keep the carbs clean, set the timing correctly and keep the water pump maintained, and you will be OK.

 

[Randy169]

Re: older inline-six cylinder failure

Chris knows what he is talking about.

Cylinder 3 is the target cylinder for most heat related problems. (It's in the middle)
Cylinders 1 and 6 on carbed systems because they get starved for fuel. (not an issue for direct injection)
I hardly ever saw cylinders 2 and 4 have issues. Lucky devils.

 

[Galaxy owner]

Re: older inline-six cylinder failure

Well I do know for a fact that the #3 goes first I just lost it 1 week ago today on my 89 115 merc my mixture should have been spot on but my water pressure was weak at idle seemed to be strong when under power

 

[monk-monk]

Re: older inline-six cylinder failure

Thanks for the replies, Sooo, why does #3 cylinder get starved for fuel ??