I need your help a knock in my 1970 Challenger 340

[brotow]

I need your help .  2 videos of a knock in my 1970 Challenger 340 6pk.  There is very little mileage on new rebuilt. I noticed the oil level was high and  thin, mixed with gas. Changed oil and filter, and fuel pump(no hole in diaphragm) no change(2nd video). Can you give me any ideas what to check?

https://www.youtube.com/watch?v=wob6Uj83oSI&feature=youtu.be

https://www.youtube.com/watch?v=aKhEi02czhs&feature=youtu.be&ab_channel=GlennRossano

[jimynick]

The videos show up as private and require a sign-in. As for the gas in the oil, there's only 2 ways for it to get there and the fuel pump is the most common (happened to me) but, you claim you've changed the pump, so the only other way is via the carbs and you've likely got a stuck float that's allowing the fuel level in the float bowl of one of the carbs to run over and directly into the engine. Does it cough out a large black cloud upon startup? Either way, if there's a knock in the engine subsequently, you've probably washed the oil film off either the rods or mains (or both) and wiped out the bearing(s). Not good any way you look at it and I'd check oil pressure to see if it's dropped. Sounds like you may want to pull the pan and have a look-see. 

[70chall440]

As stated, the videos are private so its hard to say. Gas in the oil is probably coming from one or several of the carbs, no uncommon on a 6 pack especially with today's gas.

[brotow]

I changed the  setting


                     20201018 142402  340 original noticed knock.....                https://youtu.be/wob6Uj83oSI

   20201129 175108  A knock in my 1970 Challenger 340 6pk. after oil change....       https://youtu.be/aKhEi02czhs             

[70chall440]

That sounds like something outside of the engine and my first thought was a loose flywheel. I would start checking the starter, bellhousing, flywheel, PP, etc. Also look for any rubbing although that might be even harder to find. You definitively got something banging around there.

BTW what's the deal with those spark plug boots? They are supposed to be down over the ceramic.

[jimynick]

I agree with Mike, that the noise seems to be coming from the rear of the engine more so than from inside it. Did you note that it goes away when you rev it? When it's under load it seems better. The multi frequency of the noise is different than a rod or main knock and a wrist pin knock usually comes at the float point when revved and it's not usually as "rattley" as this is. Is this a stick or auto car? Is the front balancer on good and tight, ring to hubwise? If the car's a stick, does it go away or lessen when the clutch is depressed or when it's in gear and under load? Just trying to eliminate some variables. It'd be nice if Chryco Psycho could also hear it. He's sharp on this stuff. I'll try to reach him.

[brotow]

I had the plug wires loose on the plugs. While running I pulled one wire at a time to see if any cylinder made a difference, no difference.

[brotow]

I had the plug wires loose on the plugs. While running I pulled one wire at a time to see if any cylinder made a difference, no difference.

340 6pk 904 auto, barely broken in from rebuilt by a well know shop.

[1970TA]

Loose flex plate bolts. Remove the starter and drop the converter cover. Check all the bolts.

[brotow]

I will check the converter bolts, starter was replaced. I was also considering the problem with the gas diluted oil. 

[70chall440]

I do not think the 2 problems are related; the noise is something loose and I completely agree the TC would be the first culprit. The gas in the oil is most likely a float bowl or jetting issue.

[brotow]

Found the problem causing the knock. Flex plate is loose on crank. I'm I correct in thinking the flex plate is trashed,
(elongated holes) and the bolts should be replaced. And the most important question is there a way of holding the engine in its position when separating the transmission?  Engine crane chained the the rear of the engine? Wood block under oil pan?

[jimynick]

"Engine crane chained the the rear of the engine? Wood block under oil pan?"  Either way will work and we used to use the old block of wood method- as long as you've got a stock steel pan! If it's a welded and extended pan or aluminum, I'd stick with the engine hoist angle. I had a feeling it may've been a converter related issue but wasn't 100% sure the car was auto or not. Glad you found it, but it's still a large PITA regardless. Don't forget to torque the SOBs this time. LOL 

[brotow]

A big THANKS to everyone for the help and advice, I will be ordering new transmission lines, they are twisting when trying to remove them.  Lets see how far I get before my scheduled back surgery on 12/10.

[jimynick]

If you have an oxy torch, just carefully heat the flare nuts red hot and squirt some cold water on them; then, as they still steam, squirt some good penetrant on them and using a good flare line wrench you should be able to work them back and forth and with a bit more juice, get the nuts loose from the lines so you can get them off and out. Good luck!