Oil pump failure

[Gavin]

Well this weekend I finally managed to get some time to spend on my 4610 engine problem.
My original engine was taken out of the tractor a few years ago while a temporary replacement was fitted but as to be expected nothing happened with it until the replacement failed. A few weeks ago I took the original block in to have new liners fitted and the crank reground and the engineer pointed to a crack in the crank on one of the big end journals.
Yesterday I removed the engine from the tractor and today stripped this so the crank can go off to be reground this week. Now this engine just came to a halt whilst chain harrowing one of our fields and just lost power. We towed it and got it running again but only for a few seconds before it died. This morning I removed the sump and found the cause of the breakdown. Sitting loose in the sump was the oil pump which had a fractured casting where the flange mounts to the block. Has anyone come across this before?
Incidentally I think the engineering company are going to reject this crank too for the same reason as there also appears to be a surface crack on one of the big end journals. I suspect it is only a surface heat crack but we shall see this week. I may be looking for another crank soon.