Re: [OMC-Boats] Cylinder #1

From: Andy Perakes <aperakes@...>
Date: Thu, 10 Sep 2009 07:21:36 -0400

There is an enormous amount of airflow in and out of the cylinders. For
something already moving and bouncing around, it wouldn't take much more to
suck it in and out, maybe multiple times as described by Justin. I always
viewed tinkering with carbs as more of an art than a science, but you may
indeed be at the point of diminishing returns if it is "falling apart in
your hands."

----- Original Message -----
From: "jd" <jdood@...>
To: "Evinrude & Johnson Boats of the 1960's and 70's"
Sent: Thursday, September 10, 2009 2:31 AM
Subject: Re: [OMC-Boats] Cylinder #1

> On Sep 9, 2009, at 7:09 PM, Andy Perakes wrote:
>> Is there any scoring on any of the cylinder walls (the look clean in the
>> pictures, but...)? Anything that would nick a piston would almost
>> certainly leave some kind of witness marks on the cylinder walls too.
> nope, looked for that. they all looked nice and smooth and polished.
>> If it causes a "ground out" between the piston and the valve body, it
>> will make a big noise, no matter how small. I'd be surprised if that
>> alone would cause a stall without generating obvious damage though --
>> maybe if it jammed up the valve train, I suppose. Likewise, I doubt
>> anything in the oil pan would cause a stall without generating an
>> obvious gut-wrenching noise and similarly obvious damage.
> without being an expert here, that's exactly my thinking too. in
> another post i mentioned the two little metal chunks i came across while
> cleaning. but they WERE'N't in the cylinders. So they would've have
> to go in, wreak havoc, and exit back out. But something was
> definitely in #1 and #6.
>> Is it a regular noise that tracks with rpm or an intermittent noise?
> Been 5 days now, but it was an intermittent spray can sort of rattle.
> But kinda started each time with a regular vibration as I recall. In
> fact once I though it might be the steering cables and grabbed them to
> see if it would stop. didn't.
> Throttle seemed to have an effect. High throttle (in N using red lever)
> it seemed to go away more often than not. Mid throttle, noticeable
> noise started and sometimes stalled. Idle, stall out. Always started
> right back up though. And this was only a few seconds of testing at a
> time. When things got too noisy i'd shut off engine.
>> Something that tracks rpm orders would clearly be hard-coupled to motion
>> whereas something rolling around in the pan would likely be random. If
>> a connecting rod smacked something in the pan, it could leave "ping"
>> marks in the oil pan that might be visible. If that's the case, I'd be
>> worried about one or more bent rods, but they would likely vibrate like
>> mad before eventually self-destructing. If it weren't for the stall, it
>> could be skirt or rod slap -- are you sure the stall is related to the
>> noise and not just a coincidence?
> no, not sure now after getting things back together. Now to add to the
> confusion, my carb flapper is just not working right. The little
> screw that dropped down in there, if you remember, came off the carb
> flapper thingy. So it works without the screw, but it jams up so
> easily when i fiddle with it with my fingers. plus the spring inside
> isn't bringing it back to closing fully even when it moves freely w/o
> jamming. those little rods that run on the outside and work the
> flapper and other levers i don't understand seem to be total crap.
> they're all bent - by some previous owner or mechanic as an adjustment.
> And the "tang" thing that the manual says to bend to adjust isn't meshing
> with the little arm that it seems it's suppose to move up and down. I
> don't understand carbs, so i can't intuitively figure out what "normal"
> operating is supposed to be for all those moving levers and parts.
> Combine that with jamming and i can't feel too confident bolting it back
> on and testing. Too many variable. So yeah, the carb flapper,
> esp after losing that screw, could've somehow been jamming up
> coincidentally while the noise what happening.
> It's 11 pm and i'm checking into biting the bullet and having a new
> (rebuilt) carb fedex'd to me. The current one is falling apart in my
> hands! Very frustrating to spend two hours putting everything back
> together in hopes of testing for noise only to hit a carb roadblock.
> oh yeah, and while gently tightening the nut back on the negative post
> of the coil, it broke off. So hoping NAPA has a new coil in stock
> tomorrow. Sigh.
> oh well, learned a lot tonight, had fun doing it, feel more confident
> to tear it apart again if needed later. Next on confidence building
> list....pulling the engine!
>> I think its safe to say you have all of our curiosity stirred and we'll
>> be anxious to hear what it is!
>> Andy
>> '67 Reveler
>> ----- Original Message ----- From: "jd" <jdood@...>
>> To: "Evinrude the 1960's and 70's & Johnson Boats of"
>> <omc-boats@...
>> >
>> Sent: Wednesday, September 09, 2009 6:24 PM
>> Subject: [OMC-Boats] Cylinder #1
>>> I got up super close and checked out this one. No "pitting". But
>>> some little dings from about 4 o'clock to 8 o'clock. Right where
>>> gravity would hold something. Wish iPhones had macro lenses, but it
>>> looks like teeth marks from a cat or something. Could a cat have
>>> gotten in there? Sorry. Anyway, now i wondering if this is related
>>> and i just missed whatever came out of there when i took off the
>>> head. Regardless, still cant see how spmething that would cause such
>>> tiny nicks could mske such a big noise and cause stalling. Plus I
>>> thought the zero gap plug came out of the middle, not this one.
>>> Sheesh.
>>> Option 1, I put everything back together and do a test to see if noise
>>> still there. Possibly wont be now that whatever caused nicks on
>>> piston 1 is gone. Keep in mind boat ran great judt before this noise.
>>> Old head gaskets seem pretty good / recent. No sticking, still in
>>> tact. Ok to re-use?
>>> Opion 2
>>> Take out engine, inspect oil pan, etc. Probably done for season.
>>> Again....will undoing the front motor mounts and those back bolts
>>> around flywheel housing allow me to pull the engine out with a hoist?
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Received on Thursday, 10 September 2009

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