93 20hp yamaha cooling water leak

doghunter9

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Aug 20, 2008
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I have water leaking in to the lower cowling but can't manage to find the source.
Engine has 110# on both cylinders so I am kinda ruling out the head gasket. Any ideas on a source or trick to find it? Could the power head gasket be leaking water out?

Thanks
 

99yam40

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clean and dry everything up and then run it with cowling off to see where it is coming from
 

doghunter9

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Did that. it is coming fromm under the cylinder head area. Just can't see if it's the head or power head gasket. Is the tell tale on the hard fastened to the block? I see no hose going the the hole.
 

doghunter9

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On all other motors I have seen there is a hose water hose going out to to lower cowling with the tell tail spout.
On this motor the only water hose goes from under fly wheel to the lower engine below the coil packs.
The tell tail valve on this engine seems to come from the lower engine water jacket directly.?
 

Sea Rider

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Sep 20, 2008
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Does that model has anay water plugs somewhere, check could be corroded inside and leaking, worst if engine has been used in salt water and not well flushed afterwords, Water could leak throughout any other gasket, if from cylinder head engine will be missing, loses compression on combustion chamber. But being that old would change head gasket., decarbon combustion chamber, clean all water passsages, torque to specs.

Happy Boating
 

99yam40

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OK , I understand.
I have no idea how the tell tail is rigged up on that motor as I have never looked at a 93 20.

But being as old as that motor is. there is a good chance there is corrosion that has eaten threw some where.
If you cannot see where it is coming from, then you will have open things/ remove things up to locate the leak
 

doghunter9

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Ok well I guess I will test run it on more time to try and find the source of the water. If not it is time to open it.
Any tip on where to get gasket kit for a motor of this vintage?
Yamaha don't even list this model for that year. Only 25hp
Model is cv20sd
 

99yam40

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I would wait to see what you find before buying stuff.
Might find more problems than you want to or can fix
 

doghunter9

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Any idea if I can drop the lower cowling with out removing the power head?
I think it is leaking front the bottom of the head gasket but the compression is good.
 

doghunter9

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Aug 20, 2008
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101
Ok winter project is back on
I have since replaced the head gasket on the Unit and still have a water leak.
The engine bay is very clean on this unit. I super that I have a failed gasket some her but I cant find the source. Is there a way to put pressure on the water jacket to try and find the source of the water.
I have to pull the power head to see the under side of engine where the water is coming from but then I can not start the engine obviously.
Seems that there is no plumbing hose for the water on this unit. It all seems to be plumbed into the engine casting.
 
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