Howdy

I have been trying to track down this damn knocking noise for a long time now. I have herd all kinds of different theories over the last 3 weeks.

people thought it was a valve because I have a somewhat rough idle, then some thought it was a spun bearing knocking, the idle is a different problem entirely.. I also hear a slight vacuum leak


I took it to a shop today and he told me that its 100% not the engine, its coming from the torque converter/transmission

I also learned (not to my surprise) that this is not my original tranny.


My tranny is still shifting ok, and performs well, Has anyone had they're tranny make a knocking noise randomly? as far as I can tell, its not affecting its function

It pretty much does it at idle in park


thanks as always

 

Take your shift lever and pull it back like you're going to shift it but dont change ranges fully.

If it goes away when you do this, its your shift linkage vibrating and making a knocking noise. Mine does the same damn thing, I just havent gotten around to replacing the bushings on the torque shaft.

 

interesting,

mines definitely internal though =/

 

Yeah I have that I dont know why but when im driving in the city and I accelerate and as the truck shifts smoothly into 2nd gear if i doesnt have to go into 3rd and I slow down it'll make a loud knock allways and sometimes when im slowing down from any speed (when i have been past 3rd) itll do it its like its getting stuck in 2nd is that kinda what u got ?

 

Mine is a knock like that, but it sounds more like an engine knock. only while im at idle in park or i think neutral as well,

this is why I was doing all this research on my engine.. lol

I just can't immagine what could be flying around in my tranny knocking against things. maybe its just gear teeth banging back in fourth while they arn't doing anything.. dunno


sigh...

 

I have replaced Flexplates that have cracked at the hub. Sometimes when the transmission is installed, either at the factory or privatly, a peice of wire loom or wire or something gets pinched between one corner of the engine block and the bell housing of the transmission. This makes for a bit of an angle that, when the TC is bolted up, the flexplate has to make up for. this sounds minimal, but remember that it is turning hundreds of thousands of times per day, when its distorted and has a bit of stress applied to it, it will eventually crack. it makes almost the same knocking noise as a bearing in the engine.

 

this one sounds like a u-joint, or i have also worn out splines in the tansfercase yoke of the driveshaft

 

This seems to make alot of sense to me, lemme give you one more detail I have herd. I asked that mechanic If it could be the flexplate, and he said he thought it probably wasn't because it went away when in drive. he says flex plate noise usualy gets worse in gear.. not sure if thats a hard fact or not

Ill also inquire as to how serious is a cracked flex plate? i mean it drives fine... so whatever? or is it gonna let go and throw metal into my feet while im driving?

 

well this would depend on where the crack is. sometimes when in neutral, it will rattle because its sortof loose, but when you put it in gear, it puts a load on it and tighens up and stops the rattling. if you were to start to drive and get to a speed and take your foot off the throttle, it would loosen up again and rattle, even cruising with minimal load would make it rattle.

As for how serious? well as an example. I did one that has 6, 3/8 bolt holes for the crank, and directly surrounding those are 6, 1" holes, i dont know what they are for, probobly for "flexing" lol. Anyway, the metal between 3 of the 1" holes had cracked, joining the holes, so in reality, there was only about 3" of metal holding the hub of the plate to the TC.

I would probobly diagnose and fix this ASAP.

 

http://dodgeram.info/tsb/2000/21-12-00.htm

(This goes with post #2 above)