Knocking noise?

[brothers69c-10]

I finally have my 78 k10 back on the road with the 427 tall deck. I completely dismantled the motor and put all new bearings, gaskets, cam and lifters, timing chain set and new push rods in the motor along with honing the cylinders cleaning everything up. Now that the truck runs and drives i have developed a noise that sounds like a knock or chattering. I first noticed it when i drove for the first time. the noise only came about when the engine was under load goind down the raod. it could not be heard idling or even when putting the truck in gear and holding the brake while giving it gas. it originally sounded like a rocker arm chattering so ifigured no big deal put about 50 miles on it then readjust all the valves. Now its got the 50 miles on it and the noise has progressively gotten louder and can now be heard while idling. Also it now sounds more like a knock. If you give it some gas it will sound more like a rocker chattering while going down the road. I crawled under the truck while it was running and the noise was louder underneath and almost seemed to be coming from the bellhousing area of my transmission. I have checked for exhaust leaks and have none, there are nos signs of metal or any contaminants in my oil, and all my other fluids have been topped off. the only other wierd thing the truck is doing is that when you put it clear to the floor it starts shaking real bad and won't exceed 2800 rpm's. I'm sure that part of this is due to the kick down not being hooked up, but it did the same thing with the last motor that was in it only worse cause it was a heftier built motor. I'm afraid to drive it too much for fear ruining something. I've already dropped a ton of money in this darn thing and can't afford to put much more in it right now, but we could really use an extra 4x4 around the house. So if you guys have any suggestions i would be happy to hear them and will try to provide all the information i can.

[Dieselwrencher]

I'd be ready to rebuild your TH400 either way. I know it slipped bad with the 396, so............................

[geezer#99]

Sounds like a cracked flexplate to me.

[spudz]

I think your flexplate is broken.
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[billnorman]

That or loose flywheel or torque converter bolts. We had a '55 once that the headers were hitting the frame but that was at idle, sounded like a rod knock.

[BigBlocksRule]

Flexplate or loose bolts. PITA to swap but a lot better than some of the alternatives!

[brothers69c-10]

I have already checked for the bolts being loose and they were all tight. I have not checked the flex plate yet. I thought maybe the headers were hitting the frame rail, but i cannot find any clearance issues as of right now.

[brothers69c-10]

I went out this morning and went ahead and readjusted the vlaves cause i thought i could hear them rattling too. lole and behold that got rid of the noise i thought was coming from the transmission. yet the engine still rattles when accelerating and now does it all the time and sounds like #1 or #2 rod knocking and i can see what looks like tiny little metal shavings in the oil on the dipstick, so i think i've finally hit the fed up point and might just end up getting rid of my first truck.

[spudz]

Originally Posted by brothers69c-10

I went out this morning and went ahead and readjusted the vlaves cause i thought i could hear them rattling too. lole and behold that got rid of the noise i thought was coming from the transmission. yet the engine still rattles when accelerating and now does it all the time and sounds like #1 or #2 rod knocking and i can see what looks like tiny little metal shavings in the oil on the dipstick, so i think i've finally hit the fed up point and might just end up getting rid of my first truck.

Ive been where your at.... it sucks I know. Just put it in moth balls till you feel like working on it again. If you sell it now and regret it later it hurts alot more then the frustration you are having now.

[Dieselwrencher]

You should send an oil sample to black stone before getting pissed off at the truck and giving up. I know it sucks, but you have to keep working at it to get it done.