190xt overhaul

Hi have a question on my 190xt 3 that I just overhauled. I’ve only ran it for about 5 minutes since we got it back together, I just moved it from one side of the shop to the other while I wait for an avabile dyno to break it in. It doesn’t seem to be getting a lot of oil to the rocker arms. There is plenty of flow from the port in the head and once it fills the rocker shaft, there is plenty of oil going out the outlet tube. Nothing is leaking by the corks in each end that I can see. I dissambled the rocker arm shaft and cleaned out all the small passages in the shaft for oil to pass through. Then cleaned the rockers themselves and reassembled. I used some lubriplate on the rockers during reassembly. I think the cold 15w 40 is just taking its time getting to everything. There is some oil on the bottom of most of the rocker arms and I wouldn’t be too worried about it only I know that the drain oil off the head is one of the ways the cam bearings are oiled, and those bearings along with the cam are new. My Question is if I run it some more and get the oil good and hot, then check how much oil is up top, do I risk cam bearing or cam damage? Or will the cam bearings and cam get some splash lubrication from the crank also. Thanks in advance for any replies.

Hello. Got my xt broke in on the dyno yesterday. Excluding a substantial front main seal leak that I have to fix, it went well. Only problem is the oil pressure. When it got good and warmed up, I was around 30 psi wide open and I had to adjust the pressure regulator in to get that. So I was somewhat below min spec. Before the tractor was overhauled, I could still get 35 with hot oil with the pressure regulator backed off from where it is now. I didn’t do anything with the oil pump other then remove the gear set to clean all the old oil and any crud out of the pump, and then put it back together. The gears did not look bad at all. My question is, where do I start looking for the low oil pressure cause? Would it hurt anything if I plugged the outlet tube on the rocker arm shaft then re checked the pressure? I did dissemble the rocker shaft and gave it the same treatment that I gave the oil pump. If anybody is wondering, with the dyno at the 540 rpm mark, it was putting out 98hp. I didn’t pull it down any more then that as what I do with it doesn’t require any more power and that and it was right where it was supposed to be anyway. Sorry for the long post, thanks in advance for any replies!

To be clear: the pressure regulator you are adjusting does NOT do anything once the engine oil warms up, as it is CLOSED. It is there to relieve oil pressure only when pressures exceed 55 to maybe 60 PSI, and that would be with cold oil. So, proper regulator adjustment is done when you first start the engine and throttle it up with cold oil temps and adjust it to that 55 to 60 PSI range. Once engine oil is at operating temps, that regulator does nothing as it is closed.  There is a steel seat down inside that pressure regulator passage that could be worn. That would allow leakage and could give you lower than desired oil pressures when the oil is fully warmed up. Blocking the rocker arm front oil drain tube probably won't make enough difference to really change the oil pressure numbers. Where are you measuring the oil pressure ?? Are you using a 100 psi or less gauge ??  Was the crankshaft reground for undersized bearings?? or just reused with new bearings ??  Oil pressure when warmed up fully is determined by the leakage at 7 main bearings and 6 connecting rod bearings. If they are too loose, your pressure will be lower. This assumes the oil pump GPM is adequate and within specs. 

So, if you changed nothing but new bearings on the crank (same oil pump and same crankshaft) the only thing that has been changed is the main and rod bearings.  (I just looked at specs and it is 30 to 55 not 35 to 55 like I thought.) The leakage must be the bearing clearances. I think I'd get some more run time on it and see where you finally wind up on a hot day at a slow idle say 700-750 RPM.  What weight oil ??? 15W-40 ??

Screw an oil pressure gauge right into the elbow that feeds your turbo. There should be a plug on it same size as a pressure gauge

My XT runs in the R to M of the gauge, so 35-40 psi hot ever since I’ve owned it. 80 psi AGCO gauge. Cold maybe 50 psi. A little blow by, but not bad for a 4k hr engine. Just as a reference. Not sure if this info helps or not? I’m running T4 15W-40 Rotella

Edited by AC720Man - 17 hours 11 minutes ago at 10:25pm

I don't know where or what your leaks are, or how much disassembly you're going to do to dry them up. I do know if it was mine, I wouldn't just be dropping the pan back off looking for "the needle in the haystack" without more information to work with.  I had a co-worker finish a Cat C-15 engine OH about 6 months ago. I'm the dyno test tech, so it's up to me to be sure things are correct before it gets released back to the customer or his machine. I had 70+ psi oil pressure cold. Within 30 minutes of 100% load on the dyno, it was down to 35 to 37 psi. I refused to pass it. I told him I suspicioned a main or rod bearing clearance issue. He had to drop the pan and start looking. He didn't agree with me and went his own way. First the fresh "reman" oil pump was replaced with another. He reassembled and I got to test it again and the same results. The second time he then started plasti-gauging bearings and comparing p/n/'s of new bearing shells versus the ones he removed.  He had STD main bearings where the old ones were -.010" bearings. So, it can and does happen. You haven't run this long enough to really get it HOT, like 180 degree engine oil temps, which is what it will be in the field working it. I don't think you know if it could make 70 psi of COLD psi by adjusting the relief screw in some more. If it can and if the PSI continues to drop the hotter it gets, I'm not thinking oil pump. You said it used to have 35 ?? psi before this OH ?? So with the same oil pump, why would it now be less ???...........bearing clearances.