'88 115 mercury inline stalls

I purchased an '88 115 inline on a used boat from a relative. Before letting it set in the yard for years he had the carbs rebuilt because it wouldn't come out of the hole unless you babied it . .Well the relative said the carb rebuilds fixed it but his wife said his memory is poor. It didn't help at all. When it gets over a breakover point it runs like a motor really should. It can get my bass boat up to about 45 mph according to the spedometer. I removed the tank and cleaned it and replaced the fuel lines and filter and that didn't help. I took the boat to a highly praised mercury dealer here in town who has helped me in the past and he didn't remember he had built the carbs about four years earlier and said I needed to have them rebuilt since it had set for so long with gas. As told to me by an employee, after he had the carbs off and apart he realized that they were clean and his records showed he had done the rebuild i mentioned above. He called me and said sorry but its not the carbs, its the reed valve packs. He said on the inline six, the reed valves are set up in a unit similar to main bearings around the crankshaft (there are three of them according to my mechanic) and the wear between the reed valve packs and the crankshaft have worn and postmixed gas/air is leaking into the lower cylinders past the crank and I have to replace the reed valve units at $1200 in parts plus labor. No adjusting to the carbs helps either and I still have the problem. Can this diagnosis be correct and are there any workarounds? Oversized idle jets? Either injection kits? Any suggestions?

Re: '88 115 mercury inline stalls

It's not the reeds or it would not start. You may have rings sticking from sitting around. If it was doing that before the cyl bores maybe worn out of round or tapered.

Re: '88 115 mercury inline stalls

Hey thanks for the reply but I didn't mean to imply I had a broken reed. I said the mechanic said there was blow-by inside the crankcase past the reed valve packs between the reed pack and the crankshaft. (three reed valve packs each which has forty individual reeds per pack. He showed me one he had on the shelf from a previous job where the customer backed out of the repair. Its like two halves of a main bearing in design and shape).However, as you can see I'm skeptical as to that diagnosis also. He said its from past service bulletins and experience which tells him that is what I have wrong (and it has no guarantee that will fix it )and that is why they stopped making the inline six/stacked six to begin with. However I can find no other references to such a condition other than from my mechanic. What is it which makes you believe its a stuck ring? I have no hesitation in replacing the rings, however that's a lot of work. The compression is excellent and even on all cylinders also.
Two things I did forget to mention. You can en-richen the fuel mixture/idle mixture screws to a heavy rich setting to where it idles terrible but it will come out of the hole then. Also if I hit the choke and time it right, it will come out of the hole also but that is a tricky hand over hand operation that isn't too easy to accomplish.
Thanks

Re: '88 115 mercury inline stalls

shoozz said:

. I said the mechanic said there was blow-by inside the crankcase past the reed valve packs between the reed pack and the crankshaft.

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The spaghetti seal can wear out... but it's NOT a big problem on normal used engines...
( high rpm ( Above recommended ) use can/will tear it down, due to the crank starts flexing ) .
NO likely to be the main cause on your engine...

past service bulletins and experience which tells him that is what I have wrong (and it has no guarantee that will fix it )and that is why they stopped making the inline six/stacked six to begin with.

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Would liked to see that service bulletin , I got most of those who are about the old inlines but have never seen it ...

And why they stopped producing the inline 6 engine...
It's a LATE 60s design, technology might have evolved some (I has been 20+ years on the marked ( Direct Charge engine ) ... )

Two things I did forget to mention. You can en-richen the fuel mixture/idle mixture screws to a heavy rich setting to where it idles terrible but it will come out of the hole then. Also if I hit the choke and time it right, it will come out of the hole also but that is a tricky hand over hand operation that isn't too easy to accomplish.

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Those old inline 6 engine WANT fuel, they needs to be over richen some to work properly.... tune it to idle perfect and it runs like crap... sounds familiar ??

Read tru this post ... run a link/sync job and make sure the ignition are within spec..
THEN you can tune the carburetors...

And as a last advice... make sure you got a propeller that WILL allow your engine to reach 5800 rpm at WOT, a WOT below 5500 are NOT healthy for your engine...


Arne Kjetil