2510 diesel missing on 2 cylinders, lots of blue+grey smoke

I bought a 2510 with the late model diesel engine in it. It sat for 20 years and even the owner remembered it missing on two cylinders. I put in all new injectors, a leak-down rail, a fuel transfer pump, fuel lines, and had the tank boiled and sealed with new fittings. The tractor starts easily but will only run on two cylinders, sometimes three. There seems to be fuel pressure at every injector. There is some blow-by out the valve breather, nothing excessive. No diesel fuel in the oil. No water in the oil. Valve lash is at 18-20 thousandths, nothing excessive. No bent pushrods, no sticky valves. I have the air cleaner off of it.

Tractor has the original CDC pump in it, it doesn"t really look like it"s been messed with, so i"m ASSUMING the timing is still at 6 degrees ADV.

When you run it with the valve cover off, I notice oil and air kind of splashing up out of the number 3 and 4 pushrod holes. I guess that"s blow-by... or a head gasket?

Tractor has 2400 hours on it, clutch pedal and brake pedals do not show any foot wear, three point hitch is tight and the PTO shaft splines are not worn a bit. Certainly not beat up at all.

Everything is tight and functional... it"s just this awful blue/grey smoke billowing out, half the power it should have, and two cylinders missing no matter if you idle it or attempt to pull with it wide open.

Head gasket? Low compression in two cylinders? Pump issues? Where to go next?

Thank you

could be a blown head gasket between # 2 & # 3, start it up, and while its ideling crack the injector lines at the injectors one at a time and see which 2 cylinders are missing, that will give you someplace to start.

It's close to impossible for that little rotary pump to just affect two cylinders and not all four. If you want to check, just crack each line at each injector, one by one, with the engine running. See if they all dribble the same amount of fuel. If they don't - then the pump either has two broken cam-lobes, or . . . some big gouges in the rotor. Both rare, but could happen. The cam has four lobes - one for each cylinder. If two lobes were worn/broken off, then those two cylinders would skip.

If fuel is OK, and the rocker-arms are moving as they should, I'd just pop the head off and look inside. Or, take a compression check.

Got an engine stethescope? That would be the first thing I would pull out of my toolbox. Then I would take one of the old injector nozzles,pull the insides out of it,grind the spray tip off and make an adapter for a compression gauge. Just be sure to use a 400 lb. gauge if you don't have a diesel compression tester.