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Head Gasket or motor junk

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billnh

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"So my 88 Searay 205 with the

"So my 88 Searay 205 with the Merc 4.3lx is showing good compression in all but the #3 cyl which is showing 0. Before i take the whole thing apart just looking for thoughts on it. Block? Head or just head gasket? Any easy way to tell if its just the gasket? oh ya, i have water in the oil also but the engine runs like a champ and no smoke comming out of the exhaust. Just looking for thoughts before i tackle this.
Thanks"
 
Remove the valve cover and con

Remove the valve cover and confirm the rocker arms are moving up and down the same amount as other cylinders. do this first!!

You may have a broken valve spring or stuck open (bent) valve.

If that is good then it would be time to remove the head and look at other possibilities.
 
""would that cause water i

""would that cause water in the oil also?"

No. More likely a crack in the head, block and maybe exhaust manifold or riser. Also the engine may have injested some water via the exhaust from a backwash due to a broken exhaust shutter."
 
"If you have water in the oil

"If you have water in the oil then it could be a head gasket. It could also be many other reasons..............

Has the engine been overheated recently? (260 degrees or above)


Have you used the boat yet this year?

If not, was it winterized properly?"
 
"So i bought the boat recently

"So i bought the boat recently. Had a lifter tap/rattle on the side of the #3 cyl (just trying to be specific here). Had it on the muffs for a total of about 1 hour (off and on not straight time). oil was fine. Dropped it in the lake, ran good, the lifter stopped rattling so i shut down the boat and checked the oil. Was creamy colored (water in the oil). Pulled the boat on the trailer and took it home. Started checking things out. Changed the oil, started it on the muffs and again the oil was creamy colored. Checked compression in all 6 cyl and all were perfect except #3 which showed 0 compression. Like i said, during the lifter rap, the oil was fine, the lifter stopped rapping and thats when all went to h3ll. Thanks"
 
one more thing. temp is ALWAYS

one more thing. temp is ALWAYS right around 145-150 degrees (after warm up of course). so its not overheating and it is circulating the water great as its sucking it in and blowing it out the prop.
 
"all were perfect except #

"all were perfect except #3 which showed 0 compression"

you should have at least some compression pull the head and see what you find
 
"A broken valve spring on the

"A broken valve spring on the exaust would allow some water to be sucked back. Per above, inject air and listen .carb= intake valve, valve cover= rings, exaust= exaust valve"
 
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