706 brakes

The 706 we have lost brakes only. We have hydraulics to bucket and front loader, power steering works great,but no brakes. Overfilled the system by about 4 gallon pressurized the tank with about 20 # of air,and bled brakes,but got nothing but air out of the bleeders. Its got us stumped, even took out the plug on the mcv valve and get oil out of it. But can't get brakes to work at all. Any help or ideas to get this fixed is appreciated and a step by step help is appreciated.
Thanks,
Lou & Victor

We do have a manual we bought thru this site, but no help this matter.

Lou See if you have oil with the tractor running coming from the brake valves by the pedals. If you do then bleed them again if they then will not work you are probably looking at either the o-ring on the piston in the brakes or the brake valves need new seals. If the brakes bleed out and then no brakes you will have to pull the brakes off to inspect the condition of the linings and spacers. If you find the piston is the issue you will need to pull the brakes off the get the o-ring out. Easiest way is to push it out after you have the brake disc's removed with air or oil. The air is less mess done carefully.

Check the main line coming off the top of the MCV going over to the brake valve at the brake vale first , if you havce no hyd . oil there then your problem is in the flow divider valve in the MCV or a blowen gskt in the MCV. . Now if you had a blowen O/Ring in the brake pistons you would have oil running down the sides of the tractor . If you have a I T manual there is a break down of the MCV in there and BEFORE you start taking things apart read and study the MCV section . You can remove the flow divider vaklve with out taking the MCV off the tractor . IF this valve is stuck and NOT FLOATING in the bore then this is where your problem may lay . Now you may or may not know how to bleed the brakes properly so this is how it isn done , with the engine running open the one bleeder at a time and deprees the brake pedal for that brake and hold and let the fluid run (if you get any , there are time you have to remove the bleeder before you start aand take a drill bit to it down thru the opening and clean out years of rust and dirt build up and make sure that the bleed hole is open all the way . You do not bleed them like a car or pick up . If you have a good flow of oil and still no brakes then your problem lays in the brakes them selfs as i have seen where the disc.s have sheared in half , brake dust build up , cocked pistons , messed up self adjusters , broken and smashed return springs and the list goes on . Had a guy bring me a 966 with about the same problem and his problem was a totally messed up rusted up MCV , that one was fun.

Thanks to both who answered. We do have hydraulic fluid over to the brake valve. Checked the orifice on top the mcv valve and it was clean.
Talked to a couple of mechanics at IH dealers one said if there is a air pocket in the brake valve cylinder the only way to get it out is to back pressure it with fluid with air pressure. We are going to try that first and hope it works. The other mechanic said it might be bad brings in the brake valve and it will need a kit to rebuild it. So hope for the lesser of the two evils thanks again for the help.
Regards,
Lou & Victor

Ah in my years of working on buying and selling I H tractors i have yet come across a brake vale that needs messting with, i have found lots of frozen up pins in the pedal linkage , i have found lots of brake disc sheared where the splines have come off the discs , i have seen the self adjusters froze up , eturn springs broken , rusted solid to the posta insulator pads falling off the brake pistons . and just about all of them have plugged bleeder screws . that need cleaned out . But never heard of bl;owing air back thru the system . Clean the bleeders and STAND IN THE BRAKE PEDAL , also m ake sure you pins on the pedal linkage are FREE and floating .

That should been orings not brings. We used a 2 gallon plastic clearishing lawnmower fuel tank and drilled a hole in the top of the fuel cap and added a tire valve stem,then attached a clear hose on the fuel nipple at the bottom of the fuel tank and put about a gallon of hi Tran fluid in the gas tank. Cut the regulated air pressure back to 20 lbs and ratchet strapped the tank to the tire above the height of the bleeder screw. Attached the clear hose to one side of the bleeder screw and opened it up while the tractor was running. Pumped the brake pedal until pressure was back and closed off the bleeder screw. Done the same to the other side,and have brakes a full pedal. Don't know if I explained it well enough the first time so hopefully I did this time. Thanks to all who answered and helped. According to the mechanic who we got the help from, he has run into more than a few that has had this happen to. A air lock that won't be bled out of and his way worked for us. So maybe someone else can get some use out of this knowledge if they run into the same problem.
Regards,
Lou & Victor.