Farmall 826 no lube pressure

Have a 826 gear drive tractor. I lost steering and brakes. I changed the hydraulic filter, cleaned the screen and still no steering or brakes. I put a gauge in the lube circuit and a gauge in the bottom of the MCV. I had no pressure with the tractor running.The PTO does work. I thought i would have a bad MCV gear or a sheared key. I pulled the MCV and everything looked normal. I inspected the pump- gears were scored along with the housing. I installed a new 12GPM pump and a new gasket kit, o-rings and new springs. I put it all back together, i had lube pressure for a bit then lost it.Tractor steers and i have breaks. I checked pressure on the bottom of the MCV is 210PSI@1000RPM, 225PSI @ 1500 RPM, and 225 at 2000 RPM. Also the T/A will not shift. Still no lube pressure. Any body have this happen or have experience with this issue? Im assuming i have a internal leak somewhere? Thank you

Try 5 gallon over full. Common fix for hydraulic problems. If that doesn't solve the problem get back to us. Could also be that a gasket got damaged during installation or o-ring fell out. I use a coupe of bolts with the heads cut off for guide pins or threaded rod for it. That way I can just slide the MVC up to the housing. Do the Remotes work as well as the 3 pt? If not then you need to look up inside with running and see if the shaft is turning If not it is split time. I would think since your PTO is running it would eliminate that problem though.

It is 5 gallon over full, hitch is working, PTO works, I was extremely careful installing the valve and it did not fight me at all. I also use dowel pins when installing.

You are air locked , not and uncommon problem due to age and a couple other factors . (1) Your MCV pump may be getting a little weak , (2) you maybe sucking air in several places , as in around the filter cover , this can be caused by the cover face around the bolt holes not being flat from over tighting , reuse of the old gskt. , You may be sucking air between the range transmission and the speed transmission , There could be a crack in the pick up tube at the mounting point of the support bracket . The rear pump will always prime before the MCV as it has more draw . Thinks yo0u can do to get prime is (1) run the engine at around 1800-2000 and turn the steering wheel to the left and keep on turning as this will help bleed the air out , (2) over fill above the full mark with five extra gallons , this will not hurt anything and if the tractor is setting level then the rear pick up tube is now UNDER the oil level and any slight leak either in the pick up tube of the two transmission sections is now covered . (3) you can remover the transmission dip stick and use a blow gun and a rag and add air pressure to pressurize the rear case ( word of caution here when doing this once prime is picked up DO NOT JUST PULL THE BLOW GUN OUT AND REMOVE THE RAG ) reason for this is it will shoot hyd. fluid back up out the fill hole and if you are in the shop it will rqain Hyd. oil for the next three weeks , DON"T ASK . My least favort way to get them to pick up prime is remove the 5/8ths plug on te back side of the MCV and start the tractor , now on this one it is going to make a huge mess when it does pick up prime and can dump out three to five
gallon on the floor before you can get the engine shut down.

Could have a stuck valve in the mcv

My 756 lost prime after I changed the hydraulic filter. I removed the 5/8ths plug on the back side of the MCV and started the tractor. I put a garbage bag in a 5 gallon bucket and kind of wedged it between this plug and the rear tire. I started the tractor and when it primed, it shot a bunch of Hytran right into the bag. I shut the tractor down, put the plug back in, pulled the bag out of the bucket, tied it shut and tossed in the trash. I may have gotten lucky, but, it didn't make much of a mess.

I have only done this once and did the air pressure ONCE . 99% of the time they will pick up prime running the engine at around 18-2000 RPM and turning the steering wheel to the left .

Since you have steering and, brakes, and TA pressure the problem most likely either the wrong gasket installed or a stuck valve in the MCV.