Water in Cylinders 3 and 4

J

JCH55

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1994 Mariner 40HP (4 Cyl.) Serial # OD295837

Engine will start on top two cylinders, the bottom two will not fire due to water( milky plugs) in cylinders.

Gas is good (no water).

Changed exhaust cover gaskets and cylinder cover gasket.

Compression is @120 on all 4 cylinders.

Any ideas on how water is still getting to the lower two cylinders?
 
ONERCBOATER

ONERCBOATER

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Re: Water in Cylinders 3 and 4

cracked exhaust baffle err ...this part 90421 PLATE-BAFFLE-EXHAUST MANIFOLD or its gaskets..,85491 GASKET-CYLINDER BLOCK TO BAFFLE PLATE , 85492 GASKET-BAFFLE PLATE TO EXHAUST COVER.

or 43777 GASKET-CYLINDER BLOCK COVER

Just a thought as ea of these can lead to water intrusion.

Sean

oh and of course before ordering any parts double check the part numbers that I gave you... I am dyslexic and always apt to make a mistake.:rolleyes:
 
ONERCBOATER

ONERCBOATER

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Re: Water in Cylinders 3 and 4

oh... and my favorite one... warped head, i think that one has heads separate from case... mercs mess with me as some do and some don't ore warped PLATE-BAFFLE-EXHAUST MANIFOLD if not cracked.

no promises that I am right or covered everything....just where i would look 1st.... course I would also check cylinder walls for evidence of a crack if i had heads off..... but that is me.

Sean
 
J

JCH55

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Re: Water in Cylinders 3 and 4

If it was a crack in the cylinder wall, wouldn't that show up on a compression check?

I have 120 on all cylinders.
 
M

Maxz695

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Re: Water in Cylinders 3 and 4

depends on how low the crack is if it,s at the bottom of the cylinder then you would still get compression but you would get water from the jacket. using my Gf,s pc and the keyboard is wacked
 
J

JCH55

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Re: Water in Cylinders 3 and 4

OK, I was able to replace the exhaust and cylinder gaskets without pulling the powerhead.

Is it possible to look for or test for a crack in the cylinder wall by pulling the cylinder cover plate and gasket?
 
Faztbullet

Faztbullet

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Re: Water in Cylinders 3 and 4

Lower seals on crankshaft will suck water also
 
M

Maxz695

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Re: Water in Cylinders 3 and 4

JCH55 said:
OK, I was able to replace the exhaust and cylinder gaskets without pulling the powerhead.

Is it possible to look for or test for a crack in the cylinder wall by pulling the cylinder cover plate and gasket?
Click to expand...

yes but it may be just a small hairline crack use fingernail to feel for it gently do not where a ring etc. also the next post has good advise for you. other than that if you cant detect anything magnaflux is the only other way i know how it can be detected
 
J

JCH55

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Re: Water in Cylinders 3 and 4

Faztbullet said:
Lower seals on crankshaft will suck water also
Click to expand...

Where are the lower seals on crankshaft?

I have the manual. Are they in the powerhead or mid-section lower unit?
 
J

JCH55

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Re: Water in Cylinders 3 and 4

Maxz695 said:
yes but it may be just a small hairline crack use fingernail to feel for it gently do not where a ring etc. also the next post has good advise for you. other than that if you cant detect anything magnaflux is the only other way i know how it can be detected
Click to expand...

Did not see next post with good advise. Was it the crankshaft seal idea?

What is magnaflux?
 
M

Maxz695

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Re: Water in Cylinders 3 and 4

I,m not sure but being the bottom of the crank is a part of the powerhead that makes sense to me
 
Faztbullet

Faztbullet

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Re: Water in Cylinders 3 and 4

Where are the lower seals on crankshaft?
Click to expand...

They are in the bottom end cap. This is the old tried & true 4 cylinder design and it is rare to see a crack in the liner unless it been really overheated.
 
J

JCH55

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Re: Water in Cylinders 3 and 4

Faztbullet said:
They are in the bottom end cap. This is the old tried & true 4 cylinder design and it is rare to see a crack in the liner unless it been really overheated.
Click to expand...

Captain, I see where there is an o-ring and an oil seal in the lower end cap design III.

I am relatively certain that this motor has not ever been overheated.

Is water from the water pump circulating in this area where if the seal or o-ring failed it could enter the lower cylinders?
 
M

Maxz695

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Re: Water in Cylinders 3 and 4

That would be great news to me if i where him. lets hope your correct and that he can get this thing fixed and back out there again
 
ONERCBOATER

ONERCBOATER

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Re: Water in Cylinders 3 and 4

as far as checking for cracks... i know magnaflux works on iron/steel didn't know it worked on aluminum... good to know if it does.
for me I use two shade tree tests for cracks, dye and heat.... applied heat will sometimes cause a perfect sealed crack to show... dye, i like the glow in the dark stuff or black liberally added to the part, attempt to flex the part a few times... then wipe it off and observe. sometimes this will show a crack you otherwise couldn't see or feel. cracks can be sneaky buggers!
yes the lower seal is possible you would have to remove the powerhead to reach it though I think.
small corrosion burns on any component that separates the water and fuel air mix can do that as well.
thinking about it....umm if lower seal leaking... wouldn't the labyrinth seal between 3 and 4 pretty much keep the water in # 4?

Sean
 
J

JCH55

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Re: Water in Cylinders 3 and 4

I am still confused, is there cooling water flowing through the crankshaft assembly and around the end caps?

Does anyone have a diagram that shows the water flow on this outboard?
 
ONERCBOATER

ONERCBOATER

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Re: Water in Cylinders 3 and 4

cooling flow around the cylinders.....and head....

the lower crank seal goes into the case where the crankshaft exits the case the inside (highside) of this seal is in oil bath (oil/gas it is two stroke) the outside (low side) the seal lives in an environment of exhaust gasses and water from both cooling and just sitting in the leg water....

make sense now.

sean
 
J

JCH55

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Messages
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Re: Water in Cylinders 3 and 4

ONERCBOATER said:
cooling flow around the cylinders.....and head....

the lower crank seal goes into the case where the crankshaft exits the case the inside (highside) of this seal is in oil bath (oil/gas it is two stroke) the outside (low side) the seal lives in an environment of exhaust gasses and water from both cooling and just sitting in the leg water....

make sense now.

sean
Click to expand...

Sean,
Kinda makes sense now. I am assuming you meant lake water and not leg water. This motor is on a pontoon and does not sit low in the water.

What does not make sense to me is that if cooling water is breaching the seal, I could see how it gets into cylinder #4 but not cylinder # 3.

One thing I have not checked or replaced are the transfer port gaskets (opposite side from the exhaust cover). If the lower gasket is bad, could this lead to any of my symptoms?
 
M

Maxz695

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Re: Water in Cylinders 3 and 4

Flushing engine with a source of more than 45 lbs can flood your cylinders. If you are using a hose with a signifcant amount of pressure with ther ears on if could be forcing water into your cylinders (LOWER)
 
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