Hello, I'm new to the forum I'm from Macungie PA. I have a 1993 Polaris 350L 4x4 that will not build pressure in the brakes. This model has one master cylinder that goes to the two front single piston calipers and to the rear that has one single piston. The I'll start with the maintenance I've done so far to the brakes.

New front brake calipers (left and right)
Shot air through the brake lines
cleaned the master cylinder and confirmed pressure buildup from it
Cleaned rear brake caliper
Filled up with Dot 3 brake fluid (it does say that it should Polaris brand dot 3 brake fluid but I didn't think that mattered, tell me if it does though) and tried building pressure through it and after many hours of trying had no success.

I tried the traditional method of opening and closing the bleeder valve and that didn't work. I then went to trying to put a syringe on the bleeder valve and pushing fluid back up the system but that didn't work either I saw no bubbles from the master cylinder. I started from the furthest caliper and repeated the steps multiple times.

I'm trying to figure out what is wrong and why it isn't building pressure. I don't think the brakes are out of adjustment either because they aren't moving at all.

(This machine was sitting for 20 years in a shipping container and when I pulled the master cylinder off it was just breadcrumbs, the brake fluid had become solid. I blew it out of all the lines and cleaned the master cylinder very well though.)

Any help is appreciated, I'm really confused right now why it isn't building any pressure, Iv'e bled brakes on three other machines, only one of them having a completely dry brake system before bleeding like this though.


Photo of the machine at a relatives cabin when I picked it up.

Photo of master cylinder the day I got it.

 

are you sure you got the lines cleaned? by the looks at the picture you might want to replace brake lines. I'm suprised the master cylinder is still good after seeing that picture as well and the seals haven't failed from Dring up.

 

Thanks for the response, I am 99% sure the brake lines are clear because when I had everything off I was able to put brake cleaner in one side of the line and it would drain out the other. The master cylinder as far as I know is good. When it was apart I bled the master cylinder and it made pressure and if I put my finger over it I can't keep it on there and I can feel the pressure.

I was just taking apart the rear brake which is a strange one it is mechanical and hydraulic, it has a mechanical assist thing but that wasn't working either and if I adjusted the rear brake it would lock up. I took the rear brake caliper apart and it was stuck so I am in the process of rebuilding that right now the core of the caliper is soaking in parts cleaner (I made sure to remove all the seals first).

Could the stuck rear caliper have been why it wasn't building pressure? Thanks for the response.

Here is a link to a parts diagram with a diagram of the rear brake.
https://www.polarispartshouse.com/oe...-w938139-parts

 

So I put the rear brake caliper back together and adjusted the mechanical brakes and those ended up working good, I wanted to have hydraulic brakes too though. What I did was I attached a hose to the rear brake caliper with a syringe and pushed in and it gave the master cylinder pressure, I closed the bleeder screw and then I had pressure, any time I tried bleeding it normal after that though it would loose pressure, I repeated and I had pressure again so I left it at that, the pressure isn't great, but it kind of works, does anybody know why it isn't building full pressure? Thanks.