Haulin_in_Dixie

Little more info guys.... Pan is down, crank looks great, have not measured it yet but having been a machinest, it will come out stock. The problem will be piston pin or piston, no doubt. The bearing is good, like new almost, but on the outer edges it is down to copper, just the 1/8 inch on each edge. So rod is trying to center itself.

Have to pull the head again to go further. Then I can pull the piston and see the problem. Looks like an in truck repair though, crank is good, cylinder wall is good, could be worse I guess. I will probably end up with a piston and rod replaced. Will probably have to wait for shipment on the piston.

12valve@heart

Well, I guess that's good news/bad news. Can you check wristpin play before pulling the head by moving #3 to TDC and rocking the crank or is there even a point?

Since you have it this far down, how much are you going to relace just because? Bearings are obvious. Rings since you have top and bottom open? Anything else?

Good luck and keep us posted. Hope it's no worse than it looks.

thumper 549

well in my case and hence the name "thumper" after r & r clutch,front ballancer,injetors,dropped the pan and the rest is history....nu 7 main gone completely....plastic sqirter went awol and no O.P. to the big stuff....

Haulin_in_Dixie

How can I check my coolers in the truck with head and pan off???

I would hate to go through all this and the cause is a bad squirter.

thumper 549

ez,with you pan off one or more little green tubes will be found there in the bottom of the pan. About 1.5 inches long..maybe 2"..but will be obvious.
Thats why I put in the steel ones

Haulin_in_Dixie

Pan was clean as when I put the engine in. How about plugged?

12vchevydually

Hey Haulin I Feel your PAIN, I am shure you remember talking to me about a year ago,about the noise we where having in our engine. It turned out being a wrist pin. We had to tear ours down a few times before we found the problem, because the first Machine shop said they were ok. And it was a wierd sound like how you are saying, and sometimes is seemed to quite down and other times it sounded like it was really hammering. Good Luck!!!!!!!!!!!!!!!! I am shure you will be on the road before you know it.

Marine

Bill, I think it is a wrist pin.
Oh wait...I already said that.
Mike

Haulin_in_Dixie

right now I am in a pickle. I ahve the engine down, the rod on the desk in front of me. The wear factor on the rings is fantastic, as new. The piston is perfect as is the wrist pin. This is all on number three where the knock was.

Loosening the injector on three would stop all traces of knock. The pin is tight and very snug in the rod and piston. I removed the rod bearing on four also and the mains on both sides of the rod. Cooler is in place, still don't know how to check the others that do not have the piston out.

Basically, I can find no reason for the knock. I am afraid that I took a good motor apart and somehow it is the injection pump doing it.

Marine

Well, Bill, Maybe it is the injector? If you loosen the #3 fuel line, the knock goes away? The knock is still there with different injectors?
Mike

Haulin_in_Dixie

It very definately is not an injector. I replace them as the first remidy. They had all 12 of them tested and have six tested injectors that were installed on a different head, known to be good. The knock does not move. It is far too strong of a knock to be not seen on a parts inspection. It is also a power knock. The service manual indicates that a power knock will probably be a rod bearing, not so in this case. Cummins support says that they have not heard of a vp doing this. So tore it down. Now I don't know where to go with it.

Boatnik

Everyone on board this one has good ideas and I have a couple you may want to try. I have never been this far into a Cummins but this has worked for me on other engines.

1. Try pulling the injectors. Set up a dial indicator to read off the top of the piston on each cylinder one at a time. With someones help and the piston past TDC roll the crank slowly back and forth and see how many degrees the crank turns before the gauge moves. All the readings should be close to the same. If one shows more movement than the rest it may be an indication of a bad bearing.

2. If you don't have a dial indicator that will reach thru the hole bring the piston off TDC and stick a rod thru the injector hole and push down on the piston firmly. IF it has excessive play you should feel movement. Again I haven't seen the inside of this particular engine so I don't know if you can even get there from here, but if you can it will show you if you have a bad wrist pin or conn. bearing.

SBishop

Haulin,
1. You know it is not an injector.
2. You know it is something with #3 piston/rod/bearing or injector pump.
3. At this stage of engine disassembly, you have to replace #3 piston/rod/bearing with new.
4. Upon reassembly, if no knock, it was #3 piston/rod/bearing.
5. If it still knocks, it has to be the INJECTOR PUMP.

A Hard way to trouble shoot, but you did what had to be done. You may have torn down a good engine, but you will be reassembling a good engine also. Carry on Haulin, you are making progress, just not the way you hoped it would be.

59FORD

"The pin is tight and very snug in the rod and piston."

This should NOT be the case. The pin should be free in the piston AND the rod.

I'd like to see the bearing from that jug.

I'm thinking piston slap from a wrist pin being too tight, possibly a bent rod.


Thinking out loud..........

mhuppertz

Could also be a crack around the pin boss that doesn't show up until the piston is under firing stress. Could ba a crack running along the inside of a ring land. If these are full floating pins, the rod should glide back and forth and the pin should turn freely in the piston.
Replace the piston (make sure the new one weighs the same) and pin.