Older merc inline 6 100hp

[allydog]

" I own a late 60's early

" I own a late 60's early 70's mercury 100hp inline 6 with thunderbolt ignition. I have several questions. First, I had a compression test done last year.. results were poor compression in one cylinder, less than 50psi. the other 5 were fine. I know this will effect engine performance, but is there any way to gauge how much hp I am losing? Second, since I didn't spend to much on this boat and motor I really don't want to put too much into it. I ran it all last year and it ran good. Started every time, pulled a tube fine etc... This year I replaced the plugs with Champions same as before. It seems to be running slower not as much pickup. I haven't tried pulling a tube yet but I don't think it has the power. It starts fine, but doesn't idle good. I have to play with the throttle to keep a good idle. I'm thinking maybe I got some bad gas, because after I replaced the plugs I ran the motor with the cover off and I noticed some fuel leaking from the middle carb. I tapped it a few times and it stopped. So I think maybe the carbs are gummed up. Is there anything I can get to run through the fuel to clean the carbs or will they have to be removed and cleaned by a pro? I would appreciate any comments thanks\ "

 

[danor]

seafoam is what you need to c

seafoam is what you need to clean it out. NAPA has it. Add it to the fuel as the label says.

dan

 

[tonyob]

"Ally,

The cylinder with th

"Ally,

The cylinder with the low compression is going to be a big problem at some point. The only solution is to take the engine apart and hope that you can get by with replacing the rings.

"

 

[Kirk Spradling]

" Hi,

I agree with Tony &#4

" Hi,

I agree with Tony (again). A two stroke relies on balanced pressures and the bad cylinder is throwing off the internal balance of the engine. This puts extra stress on the rest of the parts. If it helps, I just tore down a similar motor that had zero compression in one cylinder. The cylinder was ok after honing, so I got a used piston cheap and can put it back together for less than $200 including rings, piston, gasket set and machine shop work. A whole lot less than a new motor or full rebuild would cost.

Kirk "