Author Topic: Stuck Valve?  (Read 344 times)

Offline 1971ChallyGermany

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Stuck Valve?
« on: August 02, 2018 - 05:34:38 am »
Well guys, I need your advice. Sorry for not introducing myself here, but I'm in a bit of a hurry today. I'll do it later, promised.

Got a problem with my recently purchased 71 Challenger (318). Came from Cali in late June, was finally ready to go in mid July. Picked it up and well... I stalled on the first drive on the autobahn. It was a hot day, it ran fine for about 100km, then died on me. Can't get it running again, it cranks but won't start. There seems to be (gas?) blowback from the carb. Could this be a problem with an intake valve that is stuck open or rather an electrical problem? We had it running for a second a couple of times with some gas in the carb and some starter spray. Actually even with just starter spray once. The car has been sitting in a shop for 2 weeks now and they say can look at it in a month a the earliest (wish they would have told me that earlier), because they're so busy. Since I can't drive the thing all year round here in Germany and summer is running out, I would really, really like to get it back on the road sooner than that. Might move it to another shop... or try it myself, anyway whats your take on it.

Greetings from Germany




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Re: Stuck Valve?
« Reply #1 on: August 02, 2018 - 10:32:28 am »
A stuck valve wouldn't cause the engine to die.... It would cause a miss/dropped cylinder......  Blowback through the carb may be normal or it could indicate a problem with  valve timing, the fact it will run on carb spray means the valve timing can't be far off...... In fact it points to a lack of fuel reaching the carb......  I'd probably start with pumping the throttle while watching down the throat of the carb....   There should be short steady squirts of fuel down each barrel....   If not you need to check if there's fuel in the carb....    Personally I'd probably grab a tiny funnel & dump 150mL down the bowl vent.... Then test for pump shot & try starting the car.... 

Could be a plugged fuel filter, could be a bad fuel pump... Could be a plugged steel fuel line, could be air leaking into the fuel line....  The sock in the fuel tank could be plugged..... Lotta possibilities... Gonna have to do some tests to pin it down...... 

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Offline 1971ChallyGermany

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Re: Stuck Valve?
« Reply #2 on: August 03, 2018 - 05:08:26 am »
After we broke down I had the feeling it didn't get any gas. I thought the fuel line between the fuel filter and the carb was clogged. However if it was, it is not anymore. There is definitely gas coming out of the fuel filter, it's clean too. Is it possible that it's just not enough because of an air leak somewhere? Or maybe it's just a carb issue?
The shop suggested that an stuck open intake valve caused the engine to spit out the gas (blowback) thus it not getting any. Never heard of that, is it possible? To be fair though, they looked at my car 10 Minutes tops so far.

Anyway thanks for the advice, will definitely have a closer look at the carb with a (mechanic)buddy of mine next week.

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Re: Stuck Valve?
« Reply #3 on: August 03, 2018 - 09:51:14 am »
I think we have a communication snafu.... I think the valve that stuck isn't an engine valve at all.... I think perhaps the needle & seat in the carburetor stuck allowing to much fuel to pour into and on top of the engine.....   If that's the case the fuel wasn't being blown back it was being pumped out the top of the carb & spilling on the engine....  If so your lucky the car didn't catch fire.....

If thats what happened you need to pull the needle & seat out & inspect them for debris holding the needle off the seat.....   And if your car has the original carb it is super easy....Right in the front of the carb where the fuel line enters the carb the steel line screws into a brass fitting.... That fitting is the seat...... So first hold the fitting with a 9/16" (14mm) wrench & unscrew the fuel line with a 1/2" (13mm) wrench.. Then unscrew the seat with the 9/16" wrench & pull it out, look it over to see if any debris might be holding the needle off the seat...  Clean & reassemble... 

If thats what happened it would probably be a good idea to get the oil changed because allot of excess fuel winds up in the crankcase....

But with luck the car should start & run....  You might want to pull the top off the carb & see is there is debris in the bowl....   

Often these old cars sit & the fuel system gets pretty nasty...  If there is allot of debris in the carb you might what to drop the fuel tank for a look.... It might be nasty, it might be fine... All I see is a computer screen.. :roflsmiley:

Good Luck, let us know how it works out...
« Last Edit: August 03, 2018 - 09:53:26 am by 1 Wild R/T »
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline 1971ChallyGermany

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Re: Stuck Valve?
« Reply #4 on: August 07, 2018 - 05:38:14 am »
Will do, thanks  :thumbsup:

Offline 1971ChallyGermany

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Re: Stuck Valve?
« Reply #5 on: August 14, 2018 - 06:44:58 am »
Well, we've checked the carb and the fuel system, it's not that. Checked spark, it's not that. Checked compression... there you go. So the shop isn't far off, I'm gonna have to let them do it, I don't have the option to open up the engine myself. Guess I'll have to wait  :'(

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Re: Stuck Valve?
« Reply #6 on: August 14, 2018 - 08:50:10 am »
Well that sucks....
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...