Only runs with manifold vacuum leak??
#301690
04/28/09 08:12 AM
04/28/09 08:12 AM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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'70 Valiant Slant 6 4bbl carb (it came with the car).
The car has been running fine for 2 years now.
Out of the Blue...My son is coming home from work, the car dies as he takes his foot off the gas to coast.
OK what's happening is the vacuum line from the carb to the PVC is pulling so much vacuum that it's Pinning the PCV valve When this happens, the car stalls. As far as I know, I should be able to totally plug off that vacuum line without issue but yet if I take the PCV out of the loop and close the manifold vacuum with my thumb, car stalls.
Temporarily I ran a screw in the top of the PCV to adjust it from closing and car runs good.
Any ideas? this came on so sudden.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Re: Only runs with manifold vacuum leak??
[Re: mopars4ever]
#301693
04/28/09 09:16 AM
04/28/09 09:16 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Posts: 36,041
Lincoln Nebraska
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yes another pcv & get one identical to yours as diff ones meter different amts of air & if it was perfect before no reason to alter anything. The guy that built the eng probably didn't play w different pcv's but just keeping it simple.
live every 24 hour block of time like it's your last day on earth
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Re: Only runs with manifold vacuum leak??
[Re: mopars4ever]
#301694
04/28/09 09:20 AM
04/28/09 09:20 AM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Tried a new PCV valve.
More info.. no Power brakes . The only other vacuum on this car is the distributor. Any thoughts on the distributor 'breaking' and being a problem with vacuum advance? I'll pull that vacuum line off tonight when I get home.
That car has been running great for over 14K miles and from one traffic light to another... I have this problem.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Re: Only runs with manifold vacuum leak??
[Re: Tony H]
#301695
04/28/09 09:25 AM
04/28/09 09:25 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
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Circle Track
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Posts: 36,041
Lincoln Nebraska
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New PCV didn't do it? I wonder if the carb PV went bad(open) & it's needing the extra air to stay straight. do check out the carb.
live every 24 hour block of time like it's your last day on earth
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Re: Only runs with manifold vacuum leak??
[Re: RapidRobert]
#301698
04/28/09 12:11 PM
04/28/09 12:11 PM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Quote:
New PCV didn't do it? I wonder if the carb PV went bad(open) & it's needing the extra air to stay straight. do check out the carb.
After doing some reading, I think you are on the trail.
It makes sense. IF the car is having gas dumped into it because the PV is bad then it needs to Breath... The Open manifold if fulfilling it's thirst for air. I have an old Holey on the shelf, I hope it has the same # PV in it to try. Speed shops are not readily available. I need to get this car up and running.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Re: Only runs with manifold vacuum leak??
[Re: stumpy]
#301699
04/28/09 12:16 PM
04/28/09 12:16 PM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Quote:
What carb?
Holley 4160-8007 (4bbl)
Sits on an Offy Aluminum Intake.
It came with the car. I think the P.O. just took a stock motor and dumped the Out of the Box Carb and intake on the engine. Even when running reliable, it bogs a bit and hesitates and I'm sure if it was tuned for the car , the car would have a bit more jumpthen it does. But as I may have mentioned. 2 years ago, it was a $200 car and we are on the budget of a 17 year old. Who's paying his own insurance and, well everything else except college.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Re: Only runs with manifold vacuum leak??
[Re: RapidRobert]
#301702
04/28/09 05:19 PM
04/28/09 05:19 PM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Done... PV was bad.
So I am educated... #1 they can die fast and hard
#2 it will kill an engine, Maybe too much gas for the /6 anyway.
I guess it was running so rich that it needed a huge air intake Manifold leak to keep it running. The weird part was it ran very nicely with the Manifold open.
Put the new PV in, put gas in the bowl, hooked the gas line back up. 1 pump to set the choke and vroom. Let it run a while . kicked it down and all is happy.
THANKS FOR THE Power Valve idea.
And he's off to Work. what timing.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Little side affect help
[Re: Tony H]
#301703
05/03/09 01:32 PM
05/03/09 01:32 PM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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OK, the Power Valve was the issue. BUT now start the car Cold it's fine, Turn the car off for a quick Stop...get gas or run into the store come back out and car is a Bear to start. after playing in the driveway, turn off the Warmed up engine and with the Air cleaner off I see fumes coming up and it smells gassy. So what would be causing gas to bleed down the intake of the carb?
The gaskets looked good... I would think if they were bad, gas would come out of the carb not drip down the carb into the intake manifold. Would a bad Metering Body Gasket cause gas to go into the Manifold?
Last edited by Tony H; 05/04/09 01:22 PM.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Re: Little side affect help
[Re: Tony H]
#301704
05/03/09 02:44 PM
05/03/09 02:44 PM
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Joined: Sep 2005
Posts: 1,202
California
polkat
mopar addict
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mopar addict
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California
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I would agree to check the float levels. If a needle valve gets stuck open, the gas will leak down inside. This will also happen if a float springs a leak and sinks, or a power valve fails. Everything you've described indicates a too rich problem. Also, while the extra air from a leaky PCV might be helping the engine run because of the extra gas, if it leaks enough, this will pull vacuum away from the power brakes. I'd rebuild the carb, check the floats, install a good PCV, and see what happens.
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Re: Little side affect help
[Re: polkat]
#301705
05/04/09 01:30 PM
05/04/09 01:30 PM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Quote:
I would agree to check the float levels. If a needle valve gets stuck open, the gas will leak down inside. This will also happen if a float springs a leak and sinks, or a power valve fails. Everything you've described indicates a too rich problem. Also, while the extra air from a leaky PCV might be helping the engine run because of the extra gas, if it leaks enough, this will pull vacuum away from the power brakes. I'd rebuild the carb, check the floats, install a good PCV, and see what happens.
PCV is new. The Power valve, that was the original problem, is new.
The float was Light and did not rattle of gas.
The only think it could be is that maybe when I took the Gas Bowl off and layed it on it's side to replace the Power Valve, The needle valve is hanging up?
Float adjust first, then if NG I'll pop the Bowl off and look for an issue with the needle valve.
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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Found it!
[Re: Tony H]
#301706
05/09/09 10:09 AM
05/09/09 10:09 AM
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Joined: Feb 2007
Posts: 230
Long Island, New York
Tony H
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Even though the 'fog' was coming up from the Primary side, We had time to look at it last night. as soon as you turn the engine off, the Butterflies on the secondary side got wet. After taking off the secondary side bowl and seeing nothing obvious, I grabbed a can of carb cleaner and spray any orifice I could find. One of the 4 air intakes by the Pump Discharge Nozzle ( Squirters) was plugged.
That stupid little clog must have created vacuum or pressure enough to cause this problem, Blew it clear , put the bowl back on and we are good to go.
Thanks for hanging with me
'75 CJ5 with all glass body and a 350 Chevy SB '85 Chevy Stepside (the wife's) '89 Volvo All 100% maintained by me. '70 valiant DD for my son '74 Dart Swinger..Latest endeavor http://home.lyse.net/brox/TonyPage4.html
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