SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: el mojado on June 01, 2015, 11:00:27 PM

Title: Broken valve retainer
Post by: el mojado on June 01, 2015, 11:00:27 PM
So this is what grenaded #8 piston and exhaust valve. Piston chunks are all over my intake ports. Any other damage possible? Cruising at 4000 rpm when it happened. It happened instantly with no warning sounds of any kind. Just a KABOOM! What would cause a keeper/retainer to fail?
Title: Re: Broken valve retainer
Post by: che77y on June 02, 2015, 06:28:40 PM
Dam man well we all love wrenching on our boats time for a badass upgrade...... only theory but maybe the keeper never quite made it in the retainer correctly? 
Title: Re: Broken valve retainer
Post by: el mojado on June 02, 2015, 06:40:04 PM
Twisted rod. Cracked head at valve guide. Scored cylinder.
Title: Re: Broken valve retainer
Post by: philofab on June 02, 2015, 07:01:28 PM
Some cams let the valve slam shut at high rpm, and it could have just chosen that time to give up. 4000 rpm is rough on an engine.

How long had the engine been together?
Title: Re: Broken valve retainer
Post by: el mojado on June 02, 2015, 08:34:14 PM
Ran it twice last season. And twice this season. Full rebuild.
Title: Re: Broken valve retainer
Post by: GT Jets on June 02, 2015, 08:54:41 PM
Who's keepers and what retainers?

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Title: Re: Broken valve retainer
Post by: GT Jets on June 02, 2015, 09:22:31 PM
 Do you know the valve guide clearance?
Title: Re: Broken valve retainer
Post by: philofab on June 02, 2015, 09:31:15 PM
Only out 4 times? Nothing would have been worn out unless the valvetrain was setup very wrong or old parts were used.

Was the rocker and pushrod in tact?


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Title: Re: Broken valve retainer
Post by: GT Jets on June 02, 2015, 09:45:25 PM
Only out 4 times? Nothing would have been worn out unless the valvetrain was setup very wrong or old parts were used.

Was the rocker and pushrod in tact?


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If the valve stuck in the guide, the piston could have come up to say hello.
Title: Re: Broken valve retainer
Post by: el mojado on June 02, 2015, 10:27:23 PM
Used springs and keepers. Only parts which were not replaced. EVERYTHING else was new.  Rockers and push rods were all in tact.
Title: Re: Broken valve retainer
Post by: GT Jets on June 02, 2015, 10:34:06 PM
Used springs and keepers. Only parts which were not replaced. EVERYTHING else was new.  Rockers and push rods were all in tact.

Doesn't that figure?

GT
Title: Re: Broken valve retainer
Post by: el mojado on June 02, 2015, 10:34:53 PM
Yup....
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