Oil cooled piston 190 XT
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=209554
Printed Date: 22 Mar 2026 at 10:43am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Oil cooled piston 190 XT
Posted By: Leon B MO
Subject: Oil cooled piston 190 XT
Date Posted: 31 Dec 2025 at 3:15pm
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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. So got the kit and the main bearings have the oval hole for the piston cooling and the block has the port as well, but the bearings we removed had just a hole and would not have fed oil to the cooling ports. Just to be sure, it's ok to use this style bearing without a loss of oil pressure issue. Thanks Leon B MO
------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Replies:
Posted By: DrAllis
Date Posted: 31 Dec 2025 at 3:33pm
| An XT block doesn't have the small hole (.040") drilled in the upper main brg saddle for piston cooling. So, even tho the upper bearing shell has the delivery slot, the oil has no place to go. Will work fine. |
Posted By: SteveM C/IL
Date Posted: 31 Dec 2025 at 11:31pm
| 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? |
Posted By: DrAllis
Date Posted: 01 Jan 2026 at 3:19am
| I think the hole he is referring to is the main oil feed hole to the bearing. Anyway, that's how I interpreted it. |
Posted By: Leon B MO
Date Posted: 01 Jan 2026 at 6:34pm
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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. Leon B MO ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Posted By: SteveM C/IL
Date Posted: 01 Jan 2026 at 11:23pm
| if you have the cooling holes you will lose pressure.Can you crank regulator up enough to get what you want? won't know til trying it after all back together. The point is, who knows the history on that block? It could have had mains drilled for cooling but your old brgs wouldn't allow it without the slot so why?You probably have the crank driven pump so that's a plus. |
Posted By: Leon B MO
Date Posted: 02 Jan 2026 at 8:26am
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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 ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Posted By: DrAllis
Date Posted: 02 Jan 2026 at 8:42am
| HOLD ON !!! #1. Any 190XT or 200 block never had piston cooling holes drilled in them. You say it has the crank driven oil pump, then it is a 200 or 7000 or even newer than that block. But that doesn't mean it has piston cooling jets. #2. There is always one oil hole in the upper main bearing saddle. It is say 5/16" or 3/8" diameter. It is the feed hole. Are there TWO holes in this area?? A piston cooling hole is only mechanics wire size. It is not large but may have a shallow funnel drilled first and then the .040" squirtter hole. The squirtter hole is the one to plug if you don't want to use the old upper main bearing shells. Do not mess with the pressure regulator !! If you have piston cooling jets that are put into service for the first time, the oil pump (if its the wrong one) will not be able to keep up to the flow demand and you will have low oil pressure issues. Adjusting the pressure regulator does NOTHING to cure this. You would need a larger GPM pump. |
Posted By: tbran
Date Posted: 02 Jan 2026 at 9:02am
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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.
------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: Leon B MO
Date Posted: 02 Jan 2026 at 9:27am
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Cam driven oil pump. Very hard starting lots of oily blow by. We did not test injectors here we sent them in with pump for testing and rebuild. Block serial number 1261. Would post a picture of new top bearing but can't figure out how to resize to post on my phone until I get to a computer. At this point I believe we are going to just block the oil passage. Leon B ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Posted By: tbran
Date Posted: 02 Jan 2026 at 9:47am
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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. ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: Leon B MO
Date Posted: 02 Jan 2026 at 9:55am
 Sorry about pic size. Leon B MO ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Posted By: Leon B MO
Date Posted: 02 Jan 2026 at 10:03am
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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. Thanks again. Leon B MO ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |
Posted By: Leon B MO
Date Posted: 02 Jan 2026 at 2:28pm
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We drilled,tapped and installed 4mm grub screws with red Locktite in each squirter port. Should be good to go. Thanks again for the info and advice. Leon B ------------- Uncle always said "Fill the back of the shovel and the front will take care of itself". |