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Tapping sound from stock 383ci 68' Charger

The Man Called Lee

The Man Called Lee

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Not happy!
Taken me ages to get my girl running sweet.......... So I go to this show and all went well, feelin proud that I finally got her out of the garage for a real drive.
Having previously fitted new pipes I decided to rev her up a little in front of the photographers - pressin down the peddle 3 times - 3 relatively short blasts then I start getting this light to medium tapping sound............... started faintly but after a couple of minutes the tapping got louder................boy did I curse that day, and for a few days after.

So far I have,

Inspected the bottom end to look at the con rod bearings - had a bit of a look but couldn't see any issues there but to be honest she ain't knockin like you get from worn crank or con rod bearings,
Removed & inspected each lifter and push rods - all seems to be ok - she ain't missing on the cylinders and the oil seems to be circulating properly and if I remember correctly, the oil pressure is within range,
Inspected the cam lobes for any wear/damage - all seems to be ok,
Inspected each of the rockers for wear/damage - all looks good there.

Someone has suggested the tapping has a bit of an echo as though the tap is coming from inside a chamber and the sound is radiating. There is a slight vibration when you put your hand round the dizzy when the tap is heard - this guy said I might want to remove the timing chain cover to see if the tapping sound is coming from inside????

I've spent so much time thinkin about this and going over and over what I've looked at so far - tryin to figure out what else it might be. Trouble is I ain't no mechanic and I'm kinda runnin out of options/ideas what to do next. Because of my lack of mechanical experience and knowledge what to look out for - I'm wondering if I may have overlooked something?

Any advice would be really appreciated. Really ticked off as I've had her for a number of years and just haven't been able to take her out enough to enjoy yet.

If it helps - I've got a video clip of the engine running and you can clearly hear the tapping sound so I could email you guys the clip if that helps?

Thanks all.
 
Welcome to FBBO ... you should post the video here and you'll get lot's of thoughts and advise.

Maybe it's something as simple as the fuel pump rod. Easy to check ... just take it out and measure it.
 
Hey, thank you for a quick response and welcome to this site. Liking the layout and the large number of different forums.

The video clip is about a minute long so hopefully it'll load up.

Funny you should mention the fuel pump rod........... when I started my investigation I plumbed in a new fuel filter and hoses and while I was about it, as part of my early attempt to diagnose the tapping sound, I did in fact remove the pump and rod. I didn't think to measure the rod when I took it out, it 'looked' ok at the time. You reckon even though I only pumped the gas 3 times this might of done some damage or something to it?
 
OK, don't get excited. I strongly suggest you take it to a professional mechanic who's not afraid of an older car. It's probably a minor issue if you fix it right away.

In case you want to do it yourself, here's some tips:
1. Rod knock is a deep-down in the engine THUMP!...THUMP!....THUMP!
2. Valve gear knock is under the valve covers tick, tick, tick
3. You should find out for SURE what your oil pressure is since a spun cam bearing is really, really bad (but cheap to fix) & that "could" be it.
4. Get a "mechanics stethoscope" from your local parts store and try to narrow down exactly where the knock is coming from. Valve cover? Down in the block? Up by timing cover?

My gut instinct is that you probably have a valve gear issue. It could be:
1. sludge in a lifter (try engine flush but FOLLOW DIRECTIONS EXACTLY)
2. worn, bent pushrod - look at ends CLOSELY. roll each one on a mirror. Make SURE to put them back in the same hole & in the same up/down direction as they came out.
3. worn, bent rocker arm - inspect the pushrod contact area CLOSELY. put each one (cleaned) on a mirror and see if they're still straight. Put these back in the same location as they came from too.
 
Last edited:
Thanks PurpleBeeper for the comments. It's looking like a pro may have to be employed for this, coz I don't wanna make things even worse but I would like to try and fix it.

I hope the link below works for the video clip!!!!


 
check the torque convertor bolts make sure they are tight if they are loose it could make that sound
 
The Man Called Lee said:
Not happy!
Taken me ages to get my girl running sweet.......... So I go to this show and all went well, feelin proud that I finally got her out of the garage for a real drive.
Having previously fitted new pipes I decided to rev her up a little in front of the photographers - pressin down the peddle 3 times - 3 relatively short blasts then I start getting this light to medium tapping sound............... started faintly but after a couple of minutes the tapping got louder................boy did I curse that day, and for a few days after.

So far I have,

Inspected the bottom end to look at the con rod bearings - had a bit of a look but couldn't see any issues there but to be honest she ain't knockin like you get from worn crank or con rod bearings,
Removed & inspected each lifter and push rods - all seems to be ok - she ain't missing on the cylinders and the oil seems to be circulating properly and if I remember correctly, the oil pressure is within range,
Inspected the cam lobes for any wear/damage - all seems to be ok,
Inspected each of the rockers for wear/damage - all looks good there.

Someone has suggested the tapping has a bit of an echo as though the tap is coming from inside a chamber and the sound is radiating. There is a slight vibration when you put your hand round the dizzy when the tap is heard - this guy said I might want to remove the timing chain cover to see if the tapping sound is coming from inside????

I've spent so much time thinkin about this and going over and over what I've looked at so far - tryin to figure out what else it might be. Trouble is I ain't no mechanic and I'm kinda runnin out of options/ideas what to do next. Because of my lack of mechanical experience and knowledge what to look out for - I'm wondering if I may have overlooked something?

Any advice would be really appreciated. Really ticked off as I've had her for a number of years and just haven't been able to take her out enough to enjoy yet.

If it helps - I've got a video clip of the engine running and you can clearly hear the tapping sound so I could email you guys the clip if that helps?

Thanks all.
Click to expand...
I came across a similar situation a few years back and it turned out to be the PCV valve. When removed and the hole covered the noise subsided. Apparently the weight and spring are such that it takes a certain amount of vacuum to unseat the poppet. If the spring is fatiqued or you hit just the right pulsation in vacuum they will rap with a frequency. The valve cover amplifies the noise.
 
I would guess a torque converter bolt head hitting the sheet metal cover or an exhaust manifold leak.
 
I just started having a similar issue with my 440, though it may be a little quieter. At first I thought it was a light rod bearing knock, but after a fellow Mopar friend and I checked it out further, we now believe that it is an exhaust gasket leak. It went away after pulling the plug wire for #8 cylinder from the distributor (you should try this with the engine running). I will be pulling the exhaust manifold shortly to check the copper gasket there. I've got my fingers crossed!
 
Sounds like it's happening at half engine speed, roughly three times per second? Indicate something in the top end of the engine, or exhaust leak.. If you're idling it 600 to 700 RPM, it would be happening more like 10 times per second if it was crankshaft related
 
Like stated above check for an exhaust leak.
Also check to make sure you didn't install one long bolt in the crank pulley and it's hitting the timing cover.(yes I did that)!
 
Well, to me it sure sounds like a lifter/rocker/push rod, but I guess it could be an exhaust leak too. I would still want to take another look under the valve covers.

If it's exhaust, if you almost floor it for 1 second and let off the gas pedal, exhaust manifold leaks usually give a "pop, pop, pop-pop" as the engine winds down back to idle. You can also feel the exhaust leak with your hands as air blowing out around the manifold (watch out - VERY hot).

I hadn't thought about a torque converter bolt, but that would do it too. If it's that, you should be able to hear that it's coming from the front of the trans/back of motor just using your ears.

Good news is that I'm 99% sure it's not a rod bearing....sound not "deep" enough.
 
fan clutch maybe,,,fan shroud,,but im going with the other guys opinions,,just my 2 cents.... just saying.
 
Saw a trick by Edd on Wheeler Dealer to check for exhaust manifold leaks of fastening a small piece of tissue paper on a long thin stick (like a fire place match) and move it around the exhaust manifold gasket joint to look for leaks. Of course on our cars you would need to pull the belt off of the fan to avoid all that air current. Also, a lot of exhaust leaks will close up and quiet down as the motor heats up. May not do it for every one, but every manifold leak I had did so including my old 64 Sport Fury.
 
Sounds like a chunk of exhaust manifold gasket is missing some where\ or manifold is not fully seated somewhere, as that does not sound like metal hitting something say in the case of the flex plate bolts (that would also be faster ticking sound), but more like muffled combustion.

Have you checked the manifold bolts, maybe the got loose after a few heat cycles!
 
Thanks fellas, really impressed with your comments. You've given me more to work with!!!!!

I'm gonna go through everything you guys have said, some of it will be a revisit, you never know, I may have over looked summin. Will look this weekend and update on Monday to let you all know how I got on. Wish me luck!
 
It does sound kinda 'tinny', valvetrain or anything hitting sheet metal.
 
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