Oil cooled piston 190 XT

In the process of rebuilding a very tired Series 3 XT. We've had the tractor for 15 years and little by little it got harder to start. Very low compression. We have no prior history. The main bearings have 74 stamped in them and rod #1 has the serrated cap, so someone has been in there at some point. Going to check out the head and have the pump and injectors redone. Pump guy said it was wore out.

Edited by Leon B MO - 31 Dec 2025 at 3:17pm

Doc says that block doesn't have oiled holes in main saddle. You say it does. I was you and it has holes. I'd drop crank and plug them. Uppers will have less wear so you could plastigage old upper with new lower and reuse?

Curtis and I will get back to the shop tomorrow and verify, he put the crank in yesterday. Was gonna plasti gauge it tomorrow. BTW, the top bearing shells do look usable but would rather use the new ones. 

Just to verify, we ran a wire up from bearing saddle and it does come through to top So do I need to plug these holes, use different bearings or put it together as is and set oil pressure at regulator? It is a gear drive oil pump.
Leon

I hesitate to jump in here, but I am confused, think we have a diagnostic terminology issue. First it is stated a gear pump - they are all gear - one cam driven as are all 190 XT only 200 had crank driven and most combines - there will be a bubble in the front of the oil pan - AND if it is changed, unless the front axle has been raised - the axle will hit the pan. Blocks with the cam driven pump cannot use the piston cooling feature - it will be fine at first but then after a few hours the oil pressure light will come on at idle. The crank driven oil pump needs the dual filters in cold climates. The main bearing saddles will have a big hole then the small .040 hole Doc talks about to the side shooting up at the underside of the piston. Some main bearing kits contain the small bb like plug to drive in the holes to plug them when the block has been changed and using the cam driven pump. 6 .040 holes is a big leak off in the system and isn't needed. You stated the pump was sorn out - was it popping the injectors at cranking speed as indicated by white/grey smoke ? If so the pump may need the elastocast gov weight retainer installed along with a kit - but it doesn't mean the head is worn. The hardest job the pump has to do is pop the injectors at cranking speed. I would not set the injectors over 3000 PSI - we have seen injectors come back at 3500 plus psi - it is a real strain eventually on the pump on an old tractor. If the pump is put on a stand and it has the auto advance system in the bottom of the pump make SURE it is not advancing at cranking speed - We don't like to see the advance start until about 900 rpm.  IF the engine has been change it may have the pistons with the top cut back .030 to prevent scoring as started in the late 200's and combines. This reduced area above the top ring will reduce compression and results in a bit harder to start and clean out engine. Cranking speed, timing and a pump that is not over fueling is the key to starting.     

Edited by tbran - 6 hours 27 minutes ago at 9:02am

Somewhat puzzling as to history. Block has to have been changed. Maybe Doc can weigh in as to possibilities.  Either had a late model block or one out of a combine or industrial. There is a difference in the front gear on the crank, crank with longer nose between cam and crank driven units.   Front cover is the same. Definitely plug the holes somehow, with balls as from the factory kits or bearings as it had in it.  

First pic shows the elongated oil supply holes and the second has a wire going through the saddle, hard to see. Anyway, we got the answer we were looking for. Delete holes. We looked closely at the old top shells and decided not to use them, may as well do it right.