Case 930 Engine Knock and Failure

Hello everyone, Over the winter I rebuilt the engine on a Case 930 round fender, new pistons and sleeves, main and rod bearings and had the heads decked and valves done, reassembled and it started and ran amazing, lots of power burnt no oil and I was happy, it did however have a mild knocking sound right from the first startup, really only could hear it at an idle and more or less went away at higher RPM. I posted a recording of it on another engine group and several people said it sounded fine, and was normal for an old diesel, so I went on my merry way. Put about 20 hours on it harrowing and drilling, and it pulled great, then kaboom. Punched rod #1 out the side of the block and broke the camshaft in two places, looks like both lobes for the first cylinder. The rod bearing is all squished up but doesn't appear starved for oil or anything, colour is consistent. We have another block from a part tractor to rebuild it (again) but I've got to know what the problem is before I get too far, any ideas what caused the knock and eventual failure?

Did you plastigauge the rod and mains on final assembly and were the values within spec? Did you check for proper fit of the wrist pins in the small end rod bushings? Are you a long term owner of the tractor? It was a running engine just torn down to rebuild?

With the damage you describe and the forensic difficulty of interpreting the sounds it made before failure, there seems to be (from here) two possible causes. The first is that the crank was ground incorrectly for the inserts used. Which could also mean the insert on that cylinder was mislabeled, Secondly the rod may have not been torqued correctly. Follows a list:
Was plastigauge used on all journals?
Were the journals checked for uniformity on return from grinding? (including taper and egg out of round)
Were the rod bolts reused or magnafluxed to assure integrity?
Were the rods resized and checked for roundness?
Was the engine lineboared?
Did the oil pressure have any waver in it or lower than expected numbers?
What was the reason the engine was rebuilt, and what showed up when it was torn down?
is there damage to the piston indicating repeated abuse such as hitting something?
was there a fracture in the rod cap that progressed?

These are the things I would look at first. Measurement of remanufactured parts is critical. Look for the numbers on the bent bearing shell. Look at and measure the journal in multiple places if possible.
also look at the front main bearing as it is taken apart.
Good luck, Jim

The bushing at the wrist pin is a good addition. We are thinking alike. Jim

What did you measure the rod and main clearances to be.

Based on your description and reading between the lines, I would suggest a piston pin problem or a big end rod bearing problem.

Wrist pin could have been excessive piston pin clearance, wrist pin bushing shifted in the rod that shut off oil flow, plugged oil passage in the rod, rod bearing installed incorrectly that shut off oil flow to the pin etc.

Big end rod bearing could be bearing installation, big end rod diameter, loose rod bolts, failed rod bolts, crankshaft journal geometry etc.

Good luck with your next build.

Not being the resident case expert but have worked on a hand full one thing i learned on 930's was about the heads . You said you had a LIGHT knock from the start , take a good look at the top of the piston on #1 and see if you show any signs of a valve hitting the piston . and look at your cylinder heads real close and check the numbers on them and make sure they are what is suppose to be on your engine . I had a 930 come in one time for a cracked head and i found that i had cracks in all of the heads . Called around and ONE guy said he had GOOD heads that were checked with fresh valve jobs . Well they were off and 830 and yep they bolted on but when i started it i had a knock and shut it down and pulled the heads and had valves hitting the piston . Now i am not sayen this is your problem but maybe if the valve job was not done correctly and one valve was not setting deep enough when closed it could have hammered out the rod bearing to where it rolled and locked up causing the rod to break and come out the side . Just something to look at . Adn like others have said always plasti gauge your bearings during your assembly .

A Lesson I learned the Hard Way.... Always, Always Check the Crankshaft end of the connecting Rods with a micrometer to determine if they are round. Many become Egg shaped. I ruined two engines because I did not learn this lesson. I do not know it that is your problem or not.

Sounds like a rod was loose to start. Are you sure the clearance was correct? What was your oil pressure running? Did you use the correct rod cap on the rod? I had two different number 2 rods on one job and they were tight because the cap from one was used on the rod from the other. When together they fit correct but when mixed they were right.

i am always wondering what clearances were on assembly of engine, plus how much taken off heads? that seams to always be omitted in pretty well all engine trouble posts.

An engine is one thing that you cannot just put back together and have work right

We dont know if the knock and the failure are even related. Could be and injector going south with those LaNova power cells. Especially if it goes away with more throttle. If the bearing is squished but otherwise consistent in appearance, and no hammering before the failure, hard for me to believe incorrect assembly is the culprit. The bearing would have the daylights hammered out of it not look consistent . The bearing damage described must have occurred as parts were being pushed through the side of the crankcase. I dont think you did anything wrong . In short, I think you had a bad rod or bolt. Curious though, was the remains of the rod still on the crank pin or did it break farther down?

Interesting statement from someone who is elbow deep in a 12V 5.9 Cummins??? I hope you prove yourself wrong, unless I do not understand exactly what you are saying.

Same thing happened to a neighbour after he rebuilt his 930. He stopped before the engine piled up though. The knocking turned out to be caused because he installed a rod cap 180 degrees out. He installed a new bearing and put the rod cap on the correct way and all was good to go.
Ranch

A comment by a gentleman I removed all pistons,placed in a lathe removed X amount from piston top / crown and knocking never came back....

Piston can only contact head so many times......IF indeed Piston was contacting head..???

Bob...

With all do respect SVcummins.......
IF all clearances are to specs...and if all torques are to specs...and if all fuel components are to specs....the Engine had dam well better run properly.....IMHO...

Bob..

Yes but how are you going to know all that without measuring? You cant just bolt parts together and hope for the best . If it had a knock after all new bearings someone didnt measure the clearance or have the rods checked and resized if they needed it

Sorry for all your problems with this tractor. Never a convenient time for a failure like this.