Engine knock ??

[cummins32]

I've been hearing this strange knock, to me it doesn't sound deep enough to be a bottom end knock really, but that's where it seems to be coming from sort of. I have heard it for a little while and it seems worse when the truck is cold, but once it's warmed up it seems to go away. I only hear it going down the road though. it increases with rpm. I have an airdog so the stock lift pump isn't it. I've checked oil pressure before and at an idle when it was cold it was around 70psi I think, it's been awhile. Today it seemed like I could hear it very faintly when it was idling but it was very hard to hear. Then when I lifted up the boot around the 4x4 shifter I could hear it better. I put it in park and got under the truck and put my hand on everything and couldn't feel it or hear it, I can only hear it from inside the cab. I'm stumped, my next step is to cut open the oil filter. Also I put a new rear main seal in it, in november and checked the flex plate for cracks and didn't see any then. Truck has 206k on it, I change oil every 3-5k miles, When I bought it, it had 192k on it.

[JimmieD]

You have to be REAL CAREFUL DOING THIS, PLEASE! But you can either use a long screwdriver or a piece of 3/8"+ rubber tubing for a stethoscope. One end by your ear, other end placed against various components. If you're real stupid while doing it you can puncture an ear drum or get the stethoscope piece rammed in your brain etc when it gets tangled in belts. Safest is the rubber tubing because you can wrap some tape around the end if necessary to build it up so it can't fit into your ear, just against it. 3/8"+ rubber tubing should be too large to fit in ear anyway, only against. Please be careful...

[tim curran]

Your flex. Plate is cracked were the bolts mount to the crank shaft. My was doing this it got louder and louder. Drove me nuts

[cummins32]

I'll have to check it out, I would rather it be the flexplate than anything else lol, I'm pretty good at pulling the trans. Anyway to actually tell for sure it's the flexplate ?

[tim curran]

Does the noise change pitch at all from forward to reverse does it get louder when it warms up .

[cummins32]

I don't hear the knock in reverse, but it does make another noise that's hard to explain.

[tim curran]

Time for a flex plate

[cummins32]

Sweet deal lol, 275 bucks for a laminated one. I read over on comp d that a billet one doesn't flex, and they said to get a laminated one.

[cmann250]

Sweet deal lol, 275 bucks for a laminated one. I read over on comp d that a billet one doesn't flex, and they said to get a laminated one.

If you're a cheap azz (all the real 1st gen owners are ), the 6.7L flex plate is the one to have. I'm on the hunt for one now, as I sure think I tore up the stock one I have now.

[tim curran]

I just put the billet one in my truck four hundred bucks it is .25 inches thick. One rugged bitch

[cummins32]

Sweet, I'll keep an eye out for one and let ya know.

[cummins32]

I looked on patc for a laminated one and it says 89-2014 cummins, but it says only use with a lockup trans ? Does it matter

[cmann250]

The converter needs some room to move back and forth in there to account for expansion, sudden loading, the 'flex' of the flex plate, etc. Maybe the measurement stack up doesn't give the correct amount of space with a non locking converter. It never hurts to call and ask.

[Tacoclaw]

Mark Nixon seems to have a couple 6.7's hanging around his place judging from his posts over there, it couldn't hurt to give him a call and see. His number is in his sig on CompD.

[cmann250]

Mark Nixon seems to have a couple 6.7's hanging around his place judging from his posts over there, it couldn't hurt to give him a call and see. His number is in his sig on CompD.

Yea I talk with him fairly regularly. I found a 2nd gen 12v flex plate locally for free.99 and that's a hard deal to pass up.