4420 Brake Problems

Shawn4420

New User
I recently had a dealer install new drake on my 4420 now during use after and hour or two the brake pedals get hard and cannot be depressed and in turn holds the brakes on cooling the the brakes to the point I am afraid A fire could start. Does anyone know why they are building pressure and not releasing and is there a adjustment I can make on the master cylinder that will correct this?
 
Sounds like the pedal travel is out of adjustment.

But being the dealer just repaired it, and I'm sure you paid deerly for the repair, I would have them look at it and make it right.

There may well already be damage since it's been driven until it bound up.

Should be their problem. If you start making adjustments they likely will blame your repairs and refuse any warranty. At least contact them before taking any action.
 
I m not sure I would hope they did. With all that being said are you talking 3 dot brake fluid in lieu of something else?
 
Shawn: Take the cover off the master cylinder. It is under the rubber floor mat on the right side, right behind the brake pedals. You need to remove the floor plate too. Any way with the cover off push the brake pedal down and then release it. You should see brake fluid squirt up a little as the pedal returns. If it is not doing this then they may have the pedals adjusted too tight and that is not letting the master cylinder return far enough to release the pressure.

Also the wrong fluid in the brake system could have ruined the seals. It takes regular brake fluid not hydraulic oil. I have seen guys make the mistake of putting hydraulic oil in them.
 
Are you talking about a John Deere 4420 combine? If so this is what I have found over the years in running 4420's and 6620's. There is a little hole in the bottom of each side of the brake fluid reservoir which allows brake fluid to come back into the reservoir when the brake pedal is not applied. This little hole is plugged. All of the heat from the engine and all of the belts and chains, etc. warms everything up under the combine. The brake lines, master cylinder, even the wheel cylinders get warmer and the brake fluid expands pushing the brake cylinders out thereby applying the brakes. If the hole was open in the bottom of the reservoir the fluid would just expand back into it. I remember the right brake drum glowing red hot and starting chaff on fire under the combine a few years ago. Initially I thought the brake shoes were set too tight. But after it cooled the drum was free to turn. I took a small drill bit, found the little hole in the reservoir, and spun the drill bit between my thumb and index finger to "clean" or "drill" it out. Worked just fine after that. If the brake shoes (6620) or brake disks (4420) were way out of adjustment it probably would not expand enough due to heat to begin to apply the brakes. Problem occurs when you work on things - adjust shoes or disks up or install new. A little brake fluid expansion and the brakes are applied. The solution for me was to clean the little return hole in the reservoir. There are two holes. Front one supplies the piston. Back one allows for expansion. Been awhile but I think the front hole furnishes fluid for the actual brake piston. When the piston moves the back hole is covered to pressurize the system. I believe it is the back one I needed to clean. Suck all of the brake fluid out with a suction bulb so you can find that back hole.
 
(quoted from post at 21:46:48 10/13/19) Are you talking about a John Deere 4420 combine? If so this is what I have found over the years in running 4420's and 6620's. There is a little hole in the bottom of each side of the brake fluid reservoir which allows brake fluid to come back into the reservoir when the brake pedal is not applied. This little hole is plugged. All of the heat from the engine and all of the belts and chains, etc. warms everything up under the combine. The brake lines, master cylinder, even the wheel cylinders get warmer and the brake fluid expands pushing the brake cylinders out thereby applying the brakes. If the hole was open in the bottom of the reservoir the fluid would just expand back into it. I remember the right brake drum glowing red hot and starting chaff on fire under the combine a few years ago. Initially I thought the brake shoes were set too tight. But after it cooled the drum was free to turn. I took a small drill bit, found the little hole in the reservoir, and spun the drill bit between my thumb and index finger to "clean" or "drill" it out. Worked just fine after that. If the brake shoes (6620) or brake disks (4420) were way out of adjustment it probably would not expand enough due to heat to begin to apply the brakes. Problem occurs when you work on things - adjust shoes or disks up or install new. A little brake fluid expansion and the brakes are applied. The solution for me was to clean the little return hole in the reservoir. There are two holes. Front one supplies the piston. Back one allows for expansion. Been awhile but I think the front hole furnishes fluid for the actual brake piston. When the piston moves the back hole is covered to pressurize the system. I believe it is the back one I needed to clean. Suck all of the brake fluid out with a suction bulb so you can find that back hole.

Very interesting to read your reply. The exact same thing happens with snowmobiles with hydraulic brakes. Had to do the same return hole cleaning on one of mine awhile back. The only way I could release the brakes was to open the bleeder.
 
Thanks for the comments. I have talked with the dealer again this morning and they will be coming out a 3rd time but it may take over a week to get there cause they have other customers (larger farmers)
 

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