Go Back  Offshoreonly.com > Technical > General Q & A
502 valve problem >

502 valve problem

Notices

502 valve problem

Old 07-10-2009, 06:30 AM
  #1  
Registered
Thread Starter
 
Join Date: Jul 2009
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Unhappy 502 valve problem

Have had #6 cyl valve bend twice (stainless in a Merlin Head) any suggestions ?
stuntsdc is offline  
Old 07-10-2009, 06:31 AM
  #2  
Registered
 
Join Date: Nov 2005
Location: Fredericksburg, Va
Posts: 4,554
Likes: 0
Received 2 Likes on 2 Posts
Default

ck piston to valve clearance
ezstriper is offline  
Old 07-10-2009, 06:45 PM
  #3  
Registered
 
Join Date: Oct 2005
Location: Waldorf, Md
Posts: 926
Received 166 Likes on 105 Posts
Default

Stunt,
It is possible that either the valve guide clearance is too tight, or there might be something causing that combustion chamber to run a lot hotter than the others. A bad injector, vacuum leak, carb problem, ignition wire crossover etc can cause the combustion chamber temperature to be too high in the one cylinder, which in turn will heat up the exhaust valve more than nomal, causing it to expand and stick in the valve guide. The spark plugs will probably tell the story.

I doubt that it is a valve to piston problem if it is only that one cylinder. You need to have your machine shop measure the valve guide clearance snd make sure it is correct. I would almost guess if it has stuck the valve twice, it might need a new guide.

Without looking at the parts that is all I can offer ....

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
BillK is offline  
Old 07-10-2009, 07:33 PM
  #4  
Registered
 
Join Date: Mar 2009
Location: OFallon,Mo.
Posts: 1,758
Likes: 0
Received 3 Likes on 2 Posts
Default

Originally Posted by stuntsdc
Have had #6 cyl valve bend twice (stainless in a Merlin Head) any suggestions ?
I agree with Bill. Sounds like it's hangin in the guide. Can you see where it's tagged the piston? I assume that it's an intake valve (stainless). Hopefully your running Inconel exhaust valves. In a high performance marine application you have extreme high exhaust temperatures.
picklenjim is offline  
Old 07-10-2009, 09:04 PM
  #5  
Platinum Member
Platinum Member
 
MER Performance's Avatar
 
Join Date: Jul 2008
Location: Little River SC
Posts: 931
Likes: 0
Received 0 Likes on 0 Posts
Default

What valve to guide clearance are you running? what style seal? is water leaking into that cylinder?
MER Performance is offline  
Old 07-11-2009, 12:09 AM
  #6  
Registered
 
Join Date: Sep 2008
Posts: 105
Likes: 0
Received 0 Likes on 0 Posts
Default

I agree with Billk, if it's a EFI set-up #6 is allways the cyl I try to tune to. If there is a lean condition it will show up there (#6) first. You may be having a fuel related problem.
RHM253 is offline  
Old 07-13-2009, 08:25 AM
  #7  
Registered
 
Join Date: Feb 2004
Location: MT. JULIET, TN.
Posts: 3,710
Received 2 Likes on 1 Post
Default

My money is on bad machining from merlin. I had a set they didn't machine the top of the guides off correctly. Spring retainer contact = broke timing chAIin. They suk.
kennyo is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.