Broken flex plate?
 

Hi guys, This is not directly related to 1st gens,but my friend has a 2001 Dodge 1500 gasser that has a strange knock type sound that fades in neutral but gets louder when put in gear. I put a stethoscope on it and it seems to be bottom end towards the back. I don't know much else about the truck but does this sound like a flex plate?...Mark

Cracked flex plates are pretty rare in them. Usually the noise is a very sharp metallic snapping kind of noise where as a rod bearing is more of a duller type knock.

You didn't say how many miles were on it or the condition of the engine or whether it's been maintained well but if it's more of a dull, muffled type knock it's probably a crankshaft thrust or main bearing problem. If the engine has been overheated I would suspect a main bearing problem.

Thanks for the answer. It has 130k on the clock and appears to have not been too well maintained. it is a 2003 with a 4.7. What makes me suspect the flexplate is that the noise goes nearly away at idle in neutral, but becomes very pronounced in any gear. Another mechanic said piston slap, but would there be such a difference in volume of the noise when in gear if it were piston slap? I didn't crawl underneath it, but he said that there is no view plate and that there are 2 bolts missing and that it appears that the bell housing is not pulled all the way to the engine and there is a gap. I suggested that he fix that first then see what happens...Mark

Ah yeah. You would expect a mis-installed transmission to wreck a flex plate. They really aren't supposed to flex much.

It's also pretty tough on TQ (front transmission) bushings.

Yeah, if that's the case the flex plate probably is trashed.