View Full Version : loss of brakes after changing trans oil

Big Tomm
11-04-2010, 04:09 PM
I loss the brakes on my JD 2040. I changed transmission oil and noticed I didn't have any brakes. The pistons on the brake control valve are completely retracted. I tried to bled the lines without success. I also removed the plug in the bottom of the braked control valve assembly and noticed it was completely dry (NO OIL). Any advice on my next step

Big Tomm

11-04-2010, 08:31 PM
Tomm, I'm not sure I understand why you would lose brakes after changing the oil. The brake valve should be supplied oil from the pump, but it is a very slow trickle. The plug you removed from the bottom of the brake valve should have had a spring and a ball in it. If there is no spring and ball, the brakes won't work.
Since the brake valve fills so slowly, sometimes it is easier to fill it manually while bleeding the brakes. Remove the right footrest to access the top of the valve. epending on your serial number, you might have a large hex plug in the top of the valve. If not, you will have two soft plugs. Use a punch to poke a hole in one of the plugs and pry it out. fill the brake valve with Hygard oil and then try to bleed the brakes. Keep filling it occasionally until brakes are bled out. Ten install a new soft plug in the hole.

11-04-2010, 10:00 PM
Sorry to hear of your problem Tomm.

jd110 - Excellent post/reply - THANS!!!

Big Tomm
11-06-2010, 07:32 PM
JD, the plug on the bottom of the brake assembly is a very small drain plug. Not the plug with the spring and ball. I removed everything and what I have is the metal soft plugs. I have not removed them because I wanted to ask you would I still be able to bleed the brakes without the plugs. Also the pistons are completely retracted. I am wondering if I have a clog in the system preventing oil from entering the assembly. How much pressure does the pump supply . Any tips appreciated. Big Tomm

11-07-2010, 01:24 PM
The pump does not really supply pressure to the brake valve. It only trickles oil in to keep reservoir full. The brakes are applied by manual pressure only from foot pressure. Yes you can bleed the brakes while the plug(s) are removed from the top. But, if your pistons are fully retracted, they must be stuck and need to be freed up. Sometimes there is paint or rust built up on outside diameter of the pistons that makes them stick when they go in farther than their normal travel. when you lift up on brake pedal, do they still stay in? Sometimes the pedals get tight on their pivot shaft. If the pistons are protruding from the valve housing, you might be able to wrap a heay rag around the piston to protect the outside diameter and then grip them with pliers or vise grips and twist them to free them up. Then polish the outside with fine sandpaper to clean any rust or paint. If there is not enough sticking out to grab, you will need to remove the large plugs on the rear of the housing to access the pistons from that end. Disconnect the small brake lines going to each wheel and then remove the plugs. Be careful because there will be alot of spring pressure pushing the plug out. There is a ball, cup, spring, and then the piston. Remove the plug, ball(about1/4" diameter) cup and spring. Then use a long punch from the back side and tap the piston towards the front untill it stops. It helps to tie the brake pedals back so the piston makes full travel. Then polish the piston so it slides freely. reassemble, fill the reservoir and bleed the brakes.