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what are some causes for vacuum leaks?
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Author:  00spy [ Mon Jul 13, 2009 3:09 pm ]
Post subject:  what are some causes for vacuum leaks?
What are some of the main causes for vacuum leaks for the slant six.
The plugs are showing it running a little rich, and when I used the colortune to check a couple of the cylinders , it showed whiteish blue, and no matter how much I adjusted the mixture screw out it never really changed ,and never showed a yellow or orangish spark.
I sprayed some carb cleaner on the intake and around the engine , with no change in idle. Still showing a little over 15hg on vacuumgauge at idle.

Thanks for any replies
Dave
Author:  SlantSixDan [ Mon Jul 13, 2009 3:23 pm ]
Post subject: 
Vacuum leaks can occur wherever there's a gasket junction (manifold to head, manifold to carb, in between carb castings), wherever there's a vacuum hose or connector (cracked/split), or wherever there's a vacuum-operated actuator (torn/holed diaphragm). A faulty EGR valve can admit exhaust when it's not supposed to. Less commonly, a cracked intake manifold can admit air or exhaust.

Remember, many carbs made after 1967 are designed such that the idle cannot be made substantially over-rich by unscrewing the mixture needle.
Author:  00spy [ Mon Jul 13, 2009 3:33 pm ]
Post subject: 
Thanks Dan , I guess a good way to check the hoses would be to block it off from the vacuum source ,one at a time, and see if you get an increase in vacuum.

Dave
Author:  00spy [ Mon Jul 13, 2009 4:06 pm ]
Post subject: 
When I plugged up the bottom nipple on the passenger side that goes to the pcv valve , the vacuum went up to 18/19.I have that hose teed off to the charcoal cannisters also.When I plug up the hose that goes to the cannisters the vacuum does not raise any, and the same goes for plugging up the pcv side.The only way the vacuum goes up is to plug off that nipple.I hope this might bring on some suggestions.


Thanks
Dave
Author:  Wesola78 [ Mon Jul 13, 2009 8:51 pm ]
Post subject: 
I found a vaccuum leak on my slant, between the carb adapter plate and the intake.
Author:  Aggressive Ted [ Tue Jul 14, 2009 10:40 am ]
Post subject: 
00spy,
Quote:
When I plugged up the bottom nipple on the passenger side that goes to the pcv valve , the vacuum went up to 18/19. I have that hose teed off to the charcoal cannisters also.
I think you found your problem.........the PCV should go straight into the base of the carb at the back. It should not be "T'd" into anything.......

There is a fitting on the front from the base that goes to the canister. Take a look at the pictures of my carb on the red link below. Dan's links to the carb docs under the stickies will show you the same thing...........

Change it back to the stock configuration and your carb will work much better! :)
Author:  SlantSixDan [ Tue Jul 14, 2009 10:47 am ]
Post subject: 
Quote:
the PCV should go straight into the base of the carb at the back. It should not be "T'd" into anything

…unless one is trying to run a charcoal canister with a carb not equipped with a purge port. But in that case, the canister has to be plumbed in correctly with a purge valve per this post
Author:  walpolla [ Tue Jul 14, 2009 11:06 am ]
Post subject: 
click here
sorry Dan,could'nt resist it. :lol:

regards,Rod :D
Author:  00spy [ Tue Jul 14, 2009 1:50 pm ]
Post subject: 
thanks for everyones replies, I think I am going to replace my pcv valve and see if that helps. When I take off the hose that goes to the charcoal cannister , and plug it up with my hand , it take a few seconds for the thingy inside the valve(sorry for being so technical) to be sucked up by the vacuum, and some times not at all.

Dave
Author:  00spy [ Tue Jul 14, 2009 2:29 pm ]
Post subject: 
One more question. If I have an extra vacuum port on my intake manifold,would it better to run that to the cannister instead of teeing it off of the pcv hose?
Author:  SlantSixDan [ Tue Jul 14, 2009 3:27 pm ]
Post subject: 
No, do not run your charcol canister directly to manifold vacuum. That will worsen things.
Author:  00spy [ Wed Jul 15, 2009 3:51 pm ]
Post subject: 
Ok. I replaced the pcv valve, and now when I block off the hose for the cannister it goes to 18hg. Now I know the vacuum leak is coming from one of the charcoal cannisters .Is there a good place to purchase new cannisters, and I guess as long as it has the same ports any would be ok.


Dave
Author:  SlantSixDan [ Wed Jul 15, 2009 8:01 pm ]
Post subject: 
Yup, sounds like you're due for a new canister. They can't be had by application for our old Mopars, so you'll have to page thru the Standard-Hygrade fuel system parts illustrated buyer's guide (ask to see it at your stockist's). You're after a canister that has at least the same number and type of ports your present can has. Try a Standard-Hygrade #CP1014, in conjunction with the inline purge valve described at the post linked above.
Author:  00spy [ Thu Jul 16, 2009 1:36 pm ]
Post subject: 
Thanks Dan
Author:  SlantSixDan [ Thu Jul 16, 2009 2:40 pm ]
Post subject: 
Canisters are expensive on the open market, but it looks like you can get a new CP-1014 from SOS Surplus for around $10 ; call them up and ask.
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