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Author Topic: Bad Valve  (Read 9156 times)

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59VWSC

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Bad Valve
« on: October 12, 2012, 08:02:18 pm »
How would I know if I have a bad valve. Currently, my Single Cab runs terrible, has no low end power, bogs down at low rpm. Eventually, if I feather the gas pedal I will take off. Gets a little better when totally warm, but still not right.  Felt like a fuel problem, so I replaced the cheapest items, fuel filter and fuel pump. Made no difference. Motor's are not my strength for repairs. If it is a valve, is it better to buy a rebuilt long block? Please advise.
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Veeboy

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Re: Bad Valve
« Reply #1 on: October 12, 2012, 10:06:50 pm »
Do a compression check to see if you have low compression on only one cylinder.  Check plugs to see if you were running lean and check you valve clearance to see if any are running tight.  Don't know the history on your engine but don't see why you would replace entire engine for something on the top end.
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59VWSC

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Re: Bad Valve
« Reply #2 on: October 13, 2012, 07:12:22 am »
I did pull the #3 spark plug with the truck warmed up and running. Did not note any change in idle  after the plug was removed. Don't have a compression test gage.
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Veeboy

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Re: Bad Valve
« Reply #3 on: October 13, 2012, 08:50:21 am »
A compression gauge is a good investment and can be found at most any autoparts store or online form Jegs or Summit racing. If you have a multimeter, it would be good to check the ignition wires to see if you have a bad one. If that ignition wire is good then you have serious problems in that cylinder and should avoid starting and running the car until it is looked at. This is assuming that everything is good at the distributor end.
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59VWSC

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Re: Bad Valve
« Reply #4 on: October 13, 2012, 04:19:06 pm »
Veeboy!
Great advice on the compression gage. Went out and spent $50.00 for one and found out that compression was at 120 psi in all four cylinders. Probably saved me a fortune. Changed the plugs, wires, disrtibuter cap etc. Still runs lousy. No change at all. I do have a rebuilt carburator on the shelf, so I'll see if thats the problem as I have already repalced the fuel filter and fuel pump. Hopefully this will do it, if not back to the drawing board.
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lovebus (jack)

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Re: Bad Valve
« Reply #5 on: October 13, 2012, 09:20:04 pm »
what year is the engine?
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RT 66 June 1, 2015

"Why restore it to its former short comings
When you can modify it too its full potential."

59VWSC

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Re: Bad Valve
« Reply #6 on: October 14, 2012, 07:34:23 am »
Its an AE case (71) dual port.
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Veeboy

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Re: Bad Valve
« Reply #7 on: October 14, 2012, 08:42:50 am »
Distributor tight?  Points in good shape? Valves adjusted properly? Did anyone do work on the car prior to it running poorly?
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lovebus (jack)

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Re: Bad Valve
« Reply #8 on: October 14, 2012, 08:47:15 am »
Spray some carb cleaner where the manifold bolts to the heads and around the rubber boots and see if there is a change in the RPM's to see if you have a air leak
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RT 66 June 1, 2015

"Why restore it to its former short comings
When you can modify it too its full potential."

VWPANZER1

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Re: Bad Valve
« Reply #9 on: October 15, 2012, 08:46:41 pm »
 Pull one wire at a time on the distributor and see if you can isolate it to a single cylinder or the entire bank, that will give you a clue.

  The "Idiot's guide to VW's" has a great sequence of tests to help isolate: not runiing , running badly and all the other ailments.
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lovebus (jack)

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Re: Bad Valve
« Reply #10 on: October 17, 2012, 10:14:04 am »
Quote from: 59VWSC on October 12, 2012, 08:02:18 pm

 runs terrible, has no low end power, bogs down at low rpm. Eventually, if I feather the gas pedal I will take off.

Running at idle (not in gear), quickly floor the gas pedal, does it bog??
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I don't have to go to work in the morning....

RT 66 June 1, 2015

"Why restore it to its former short comings
When you can modify it too its full potential."

59VWSC

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Re: Bad Valve
« Reply #11 on: October 17, 2012, 08:26:56 pm »
Yes it does. You have to keep "feathering" the gas pedal for it not to bog down.
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lovebus (jack)

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Re: Bad Valve
« Reply #12 on: October 17, 2012, 08:35:39 pm »
Your spray jet is clogged, simple fix but you must make sure it is put back in tightly.
 
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I don't have to go to work in the morning....

RT 66 June 1, 2015

"Why restore it to its former short comings
When you can modify it too its full potential."

59VWSC

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Re: Bad Valve
« Reply #13 on: October 17, 2012, 09:07:47 pm »
Sorry for another dumb question, where on the carb is it?
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59VWSC

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Re: Bad Valve
« Reply #14 on: October 17, 2012, 09:14:26 pm »
Is it the main jet (adjacent to the Electromagnetic cutoff valve)?
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