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Brad @ SCJB

  • Karma: +255/-0
Broken Valve
« on: February 18, 2011, 12:19:23 PM »
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



Then I pulled the exhaust log and stuck my finger in the #5 port...yup, just a valve stem.



Pulled the head.....awww shit  :banghead:





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  :(

  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
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obnoxious001

  • Karma: +4/-1
Re: Broken Valve
« Reply #1 on: February 18, 2011, 01:14:23 PM »
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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Brad @ SCJB

  • Karma: +255/-0
Re: Broken Valve
« Reply #2 on: February 18, 2011, 01:21:38 PM »
no idea what kinda valves they were....but they are were 990 heads.
  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
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obnoxious001

  • Karma: +4/-1
Re: Broken Valve
« Reply #3 on: February 18, 2011, 02:54:57 PM »
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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ka0tyk

  • Karma: +30/-0
Re: Broken Valve
« Reply #4 on: February 18, 2011, 03:01:55 PM »
isnt there a specific make of valve where its actually 2 pieces and they tend to split like that?
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HomeBlown57

  • Karma: +0/-0
Re: Broken Valve
« Reply #5 on: February 18, 2011, 06:03:59 PM »
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!
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