Oooh geez, now what? 756 Farmall

I bought this tractor 2 years ago at auction, its
been a good tractor so far but today something
came up and at this point I'm not exactly sure
what it might be. Hoping for some help here. 756
Farmall with the 310 German Diesel engine

I was driving down the road in road gear, noticed
a bit of smoke and a slight loss of power. It was
about a 1/4 mile later that I notice fairly heavy
white smoke coming from the blowby tube, also I
notice a knock coming from the engine. Not a loud
hammering knock, but a obvious knock louder than
the diesel cylinders firing. I shut it down right
away, I checked the oil, it was full, but very
very clean looking. Now just 15 minutes earlier
prior to startup I had checked the oil and it was
pretty black, not sludgy, just black. Why would
oil clean up like this? What was causing the
white smoke from the blow by tube ?

I let the tractor sit for an hour or so, I
loosened the oil pan drain, got about 3
tablespoons of antifreeze, then black oil. I
restarted the engine, the knock is still there,
but no more white smoke from the blowby tube. The
engine sounds great like its firing on all
cylinders, just got a darn knock in there.

What happened?? I'm fearing a cavitation issue,
but hoping for something simpler.

Sounds to me like you got coolant in the oil and spun a rod bearing

I think 856 has it. Is the knock worse when throttling up or under load? That's rod bearing. There's no other sound like it. Don't run it and you may be able to save the crank. Pull it apart.

I think you guys are right in that it"s a spun bearing. That may not be too bad to fix depending upon how much damage has been done. Now my concern is why did the bearing spin? Lack of lubrication I"m sure, and likely due to the water in the oil. Is there really any way to test where the water is coming from? I"d hate to resleeve all cylinders just to find out that it"s the block that cavitated.

I haven"t tore it down yet, and won"t be able to for a while, but I"m really curious to find out exactly how all this happened and how much damage it caused.

Hi, German Diesels have two common problems, first injection pump front seal leaking Diesel into crankcase and diluting crankcase oil, second was the O-rings on the bottom of the cylinder sleeves leaking coolant into the crankcase. Possibly sleeve cavitation allowing coolant into cylinder.
Also a stuck or leaky injector can cause white smoke out the exhaust. Test for leaky O-rings, drain crankcase oil, leave drain plug out of crankcase and place clean container under drain plug, leave it sit for a day or more, check container for coolant.

JimB