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  #1  
Old 06-24-2007, 08:32 PM
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What's the best way to check cylinder head valves for leakage?

What's the best way, without taking a head to a machine shop, to check if the valves leak? I have a couple of heads off of 617's that I suspect that some of the valves leak. After testing the compression on one when it was still on the block lead me to think that. After adding oil to the combustion chambers, no increase in compression was achieved on a couple of the cylinders.
I poured a little Marvel Mystery oil into all the intake and exhaust ports of the removed heads to see if any of the valves leak. There were a few that did indeed leak.
Am I going about it in the right way by doing this way or will valves leak any way by adding MM oil to them?

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  #2  
Old 06-24-2007, 08:39 PM
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is the cam still on the head?
if the valves were recently adjusted, but not driven much after, they could still leak if they are good. I would remove the springs and visually inspect the valves for grooves and cracks/burns and such. valve lapping compound is affordable, and pretty simple to do, if no cracks or burns are evident.
spring pressure should hold back fluid if the valves are good.
http://www.v6z24.com/howto/valvelapping
http://www.powrgrip.com/cgi-bin/powrgrip/V1275.html
http://www.goodson.com/store/template/product_display.php?NID=61
here is a link to a forum discussion of valves/ and lapping etc...
http://cartalk.com/board/showthreaded.php?Cat=0&Number=328489&page=0&vc=1
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  #3  
Old 06-24-2007, 08:45 PM
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Leak down test.

http://www.xs11.com/tips/misc/misc3.shtml
http://en.wikipedia.org/wiki/Leak-down_tester
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  #4  
Old 06-24-2007, 08:48 PM
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Lance, that's not really an option with the head off the motor...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #5  
Old 06-24-2007, 08:50 PM
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No, both of these heads are off their engine blocks. I haven't looked at the valves nor seats yet. I only have a lever type valve spring tool to take valves apart, the type that takes advantage of a rocker arm stud as it's fulcrum. I'm not sure one of these would work to remove valves on a 617 head and even less likely to reinstall the valves.
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  #6  
Old 06-24-2007, 08:53 PM
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Originally Posted by vstech View Post
Lance, that's not really an option with the head off the motor...
Ok. I thought the original idea was to prevent the need to remove the head.
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  #7  
Old 06-24-2007, 08:54 PM
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No, one head was off already and the other I pulled after finding some bad compression results on the other engine.
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  #8  
Old 06-24-2007, 08:56 PM
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liet

why dont you try a real simple test, remove the cam shaft, lay the head with valve stems up,place paper towels under head,fill the ports up say about 1/4 in with fluid,if the valves leak the fluid they are bad.
larry perkins lou ky
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Old 06-24-2007, 08:57 PM
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When I did a valve job on my 616 head (under the watchful eye of my import indy buddy) I was told to fill the ports with solvent and leave it for a few hours, which is what you did. You might try just lapping them. Then try the "solvent soak", Whata ya got too lose
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  #10  
Old 06-24-2007, 09:01 PM
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Quote:
Originally Posted by larry perkins View Post
why dont you try a real simple test, remove the cam shaft, lay the head with valve stems up,place paper towels under head,fill the ports up say about 1/4 in with fluid,if the valves leak the fluid they are bad.
larry perkins lou ky
That's kind of what I've already done using MM oil. See post #1.
Should I try something a little less penetrating?
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  #11  
Old 06-24-2007, 09:02 PM
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Quote:
Originally Posted by Stevo View Post
When I did a valve job on my 616 head (under the watchful eye of my import indy buddy) I was told to fill the ports with solvent and leave it for a few hours, which is what you did. You might try just lapping them. Then try the "solvent soak", Whata ya got too lose
That sounds like a good idea as I've got nothing to lose at this point.
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  #12  
Old 06-24-2007, 09:10 PM
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lapping valves

folks you had better read about valve laping,big mistake.
just my opinion
larry perkins lou ky
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  #13  
Old 06-24-2007, 09:32 PM
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Quote:
Originally Posted by larry perkins View Post
folks you had better read about valve laping,big mistake.
just my opinion
larry perkins lou ky
Whats the deal? not a good idea??
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  #14  
Old 06-24-2007, 09:45 PM
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Quote:
Originally Posted by larry perkins View Post
folks you had better read about valve laping,big mistake.
just my opinion
larry perkins lou ky
Any sources you can cite? I'd really like to read up if there's something to look out for.
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  #15  
Old 06-25-2007, 12:36 AM
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remove the head pour a solvent over the valves and put pressurised air into the exhaust and intake of each cyilinder. you will see where the bubles are coming from.

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