SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Brad @ SCJB on February 18, 2011, 12:19:23 PM
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Well, I finally cracked into the Southwind's motor today....and its worse then I thought. :banghead:
The last time I took it out (August)....It shut down at WOT and turned over, but wouldnt start. I got it home, pulled the plugs and found water in all 8 plugs and #5's plug was smashed to shit.
I then put the cover on it, put it on the side of the house and got to work on the race boat. Play time was over.
Well, I finally got around to ripping into it to assess the damage....
First thing I saw was a failed hydrolic lifter on the exhaust port on #5
[attachimg=1]
Then I pulled the exhaust log and stuck my finger in the #5 port...yup, just a valve stem.
[attachimg=2]
Pulled the head.....awww shit :banghead:
[attachimg=3]
[attachimg=4]
So here's what I think happened....
The lifter failed and expanded pushing the valve wide open and kissed the piston. It then broke off, bounced around, broke off the intake valve and made a window in the combustion chamber of the head letting water into the cylinder and then flooding into the other 8 cylinders...thus why all 8 plugs were wet.
so.....I got a pile of junk. ......now what? Looks like its gunna be one of those summers :(
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More than likely the exhaust valve failed first, very typical problem in marine engines. Any idea what they were?
I always suggest at least severe duty exhaust valves on NA engines, and extreme duty for forced induction engines due to the extra abuse.
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no idea what kinda valves they were....but they
are were 990 heads.
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no idea what kinda valves they were....but they are were 990 heads.
Are both of them wrecked? I may have a single here.
Marine engines get run harder than "street" engines, and exhaust valve failure is pretty common in a boat engine. I have a collection of damaged heads that I need to let the scrap guy pickup.
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isnt there a specific make of valve where its actually 2 pieces and they tend to split like that?
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I have a forged crank that needs to be turned, if you decide to rebuild it. I got it from this nice guy that has had some bad luck with engines lately. I'll sell it to you for $125!