Anyway to Seafoam (not seafood) mercury 6 hp 4 stroke top end without running it

rdhj

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my 6hp isn't taking a really long time to start or not starting all off a sudden but ran find the last time after i finally got it started. compression test is only reading around 12 psi and doing a leak down at TDC you can hear air leaking out prop and the piston rings....checked the valve clearance and they were a litle too wide of a gap. Therefore, I adjusted them to the middle off the specs. I'm guessing that the valves are either really dirty or stuck...rings could also be stuck...pulled intake off and there was a lot of carbon on back of intake valve.

Question is...how can I go about trying to clean the piston, rings, and valves with seafoam without running the engine....is there anyway to tell if the exhaust valve is stuck without taking it all apart./???

Note that everything else was checked and is good such as fuel delivery and spark and choke operation
 

tpenfield

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Your thread title says 'seafood'. If that be the case, then no wonder you have poor compression :D Seafood would definitely cause problems.

You can run a cylinder leak test, which will give you an idea of where the problem lies (valves, rings, etc).
 

Scott Danforth

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Question is...how can I go about trying to clean the piston, rings, and valves with seafoam without running the engine....is there anyway to tell if the exhaust valve is stuck without taking it all apart./???

pull spark plug, fill cylinder with ring free or a mixture of acetone and atf (50% acetone, 50%ATF)

let sit

repeat

repeat

drain crank case

refill with oil

and you may have unstuck stuff

or pull it apart and correct the issue.
 

rdhj

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Your thread title says 'seafood'. If that be the case, then no wonder you have poor compression :D Seafood would definitely cause problems.

You can run a cylinder leak test, which will give you an idea of where the problem lies (valves, rings, etc).

I actually did a leak down test and it doesn't look good...i can hear air coming our the prop making me think the exhaust valve is either stuck or something and i seems to be letting air past the rings, which could be stuck or worn.....the leak down gauge reads 0 on the high side gage when the left gauge air source gauge is reading anything from 20 to 70 psi....

would stuck valves and rings give you no compression or should I at least be getting something on the gauge...you can feel air coming out the spark plug hole when covering it with a finger
 

tpenfield

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Could be stuck or broken (tulip’ed)

i don’t think Seafoam is going to do much.
 

GA_Boater

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Your thread title says 'seafood'. If that be the case, then no wonder you have poor compression :D Seafood would definitely cause problems.


Fixed the seafood reference in the title.

Are you sure about 12 PSI compression. A motor can't run with that little bit of compression. Try another gauge.
 

QBhoy

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Fill the whole thing with diesel and leave it for a few days. Right to the brim...empty, flush with oil, then refill to correct level on dip stick. That will do the trick, if it's only what you suspect the problem is.
Is the timing belt ok ?
 

rdhj

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I've been contemplating the compression test and Lead test that I did and wondering if it is correct because they're actually is compression there. Just trying to figure out why I was getting 12 PSI on the compression gauge and when I did the leak down test why I only gotten zero PSI on the right hand gauge. Delete down tester I have is different than most. Just can't figure out why everything checks out but it does not start
 

rdhj

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I am sure the gauge works as I used it on my car and it was fine. Does anybody else have a 6 horsepower Mercury and has use the repair manual. According to the manual it says the marks that you use for determining top dead center or on the right hand side looking from the front of the motor Is anybody else found this to be wrong
 

rdhj

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Thanks for the diagram that shows the same thing that my manual shows So I guess there's a possibility that maybe the key has sheared. If I set it up as shown in the picture my piston is at bottom dead center. Is it unusual for one of these keys this shear
 

GA_Boater

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Before the motor started running poorly/not starting, did the prop hit anything? That's one of the causes of sheared keys.

i would check the key.
 

rdhj

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The prop hitting something is highly likely as I use this for duck hunting and some of the rivers near me get really shallow and I hit things all the time
 

rdhj

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I pulled the nut and washer off the flywheel and I see the key inside the slot of the flywheel. So, I am assuming this is not my issue...Is there any other way the timing could have gotten messed up without this key breaking?
 

GA_Boater

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If the key shears, you will see the broken key in the flywheel slot. What you can't see is the part of the key in the crankshaft.

Pull the flywheel.
 

rdhj

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Just pulled the flywheel off today and the key is fine...so puzzled.....is there anyway the crankshaft could have got flipped around or something....with the piston at top dead center, the little notch under the fuel pump is showing but the letter T lines up with the line on the side with the fuel pump, not the line shown in the manual
 

GA_Boater

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Just hit me - This is a 4 stroke. :doh: The timing marks only line up every other revolution. Make another turn of the flywheel.
 

rdhj

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i turned the flywheel a ton of times and it never lines up with the right marks
 

racerone

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Ignition timing marks on a single cylinder 4 stroke motor usually line up EVERY revolution.-------Meaning it fires on the exhaust stroke too.
 
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