My neighbor has a '17 touring that has a knock what seems to be either 1 or 2 rod. It makes what sounds like thump thump while hand cranking slow. when #1 is top dead and 2 is at the bottom.It sounds like 2 more than 1. I took the rod caps off and took a shim out to tighten it up a bit. I did notice the babbit on #3 was loose so I took it off and replaced it with a spare rod cap, but it still has the same thump sound. You can actually feel it in the crank when rolling it over. There isn't any carbon build up in the head that I can see also. Any thoughts?

Rather than retype much of what's already been said, please follow the link and consider if this is possibly your problem...

http://www.mtfc a.com/discus/me ssages/118802/1 49442.html?1278 567414

I'm sorry for the poor information, The thumping sound isn't 180 off as the others said. This is right at tdc and just off of tdc the thumps are back to back, and it sounds the same cranking fast or slow. I guess we will pull the head and go from there. Also I was cranking while laying under the car when you get to that spot its hard to crank and it will stop you if you don't have momentum

I'd open the transmission inspection cover and have somebody stationed at that point to see if it looks or sounds like it's back there.

I wonder if one of the flywheel bolts is backing out? You can see these just behind the rear main bearing (4 of them) when looking through the bottom inspection cover. A bit more difficult if the motor has it's original 3-dip pan (you might need a mirror) If someone didn't safety wire them I think they can back out just enough to rub the rear main bearing cap. Just a thought.

I'm assuming that you have the head off since you mentioned inspecting for carbon build-up. If the head is bolted down, you might want to back off all the head bolts (after draining the coolant) and see if the head lifts up as the pistons each come to TDC. My thought here is that perhaps someone planed the head a bit too much and the clearance on a couple of chambers is not there. Look for marks on the piston tops where they may have made contact. If the engine has an aluminum head (you didn't mention one) it could be one of the 'Z' heads that were produced with a clearance problem which can usually be corrected. Look for a Z near the water outlet at the front of the head on the top to identify a 'Z' head.

Warren,
It was carbon build up on #1. It is an aluminum head and pistons, Have it all cleaned up waiting for gaskets. I should have gone with the gut and removed the head 1st. Thanks
Doug