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My brake will compress but it will not return. What is happening is something is not allowing the brake fluid to return to the decompressed state. When I open the bleeder valve on the slave cylinder caliper will return and the fluid will bleed out. I have inspected the inside of the slave cylinder, blown air through the brake line, blown air through the elbow from the master cylinder fill reservoir, visually inspected the master cylinder and removed all components and cleaned them and re-assembled. All seems to work fine unassembled. I need input from you.

Thanks

Rear brake pins with a worn groove...worn out/damaged dust seal, fluid seal, etc. ?

I had the same problem with the one on my 220.... Would compress but on release it would make the brake drag.....i found that the master cylinder piston had corroded after years of use.... No repair kit could fix so I opted for a second hand unit, now everything's good

For me, this problem was due to a gunked up wheel cylinder and piston.

Had to use air pressure for several minutes to remove piston.

After thorough cleaning and new seals, it now works like it should.

Actually, there was no problem with the seals. It was all the junk build-up on the piston and cylinder bore.

The caliper will move in and out with the bleeder valve open. The caliper will not compress back into the slave cylinder with the bleeder valve closed.

I have seen the inside of a brake hose tear and create a flap of rubber that acted as a one way check valve. You could apply the brakes but the caliper would not release unless you opened the bleeder. Instead of opening the bleeder, crack the line at the caliper. If the pressure releases, tighten it back up and try again but this time crack it at the master cylinder. If it doesn't relieve the pressure, I would replace the brake hose.

I don't think blowing air through it is a good test.

Rebuild kits are cheap and easy for both the master cylinder and caliper. I'd rebuild them both and go from there. At the very least, disassemble them both and make sure everything is clean, look for corrosion or damaged seals, clear all the passages, etc...

david wrote:I have seen the inside of a brake hose tear and create a flap of rubber that acted as a one way check valve. You could apply the brakes but the caliper would not release unless you opened the bleeder. Instead of opening the bleeder, crack the line at the caliper. If the pressure releases, tighten it back up and try again but this time crack it at the master cylinder. If it doesn't relieve the pressure, I would replace the brake hose.

I don't think blowing air through it is a good test.

I was just gonna mention that too.... I've seen the brake thing happen several times, in both cars and bikes. If the piston compresses when you crack open the bleed valve then more than likely it's the brake hose

thirdgenlxi wrote:

david wrote:I have seen the inside of a brake hose tear and create a flap of rubber that acted as a one way check valve. You could apply the brakes but the caliper would not release unless you opened the bleeder. Instead of opening the bleeder, crack the line at the caliper. If the pressure releases, tighten it back up and try again but this time crack it at the master cylinder. If it doesn't relieve the pressure, I would replace the brake hose.

I don't think blowing air through it is a good test.

I was just gonna mention that too.... I've seen the brake thing happen several times, in both cars and bikes. If the piston compresses when you crack open the bleed valve then more than likely it's the brake hose

I will 3rd this! Ironically I actually have a partially collapsed soft line on the front of my truck right now

david wrote:I have seen the inside of a brake hose tear and create a flap of rubber that acted as a one way check valve. You could apply the brakes but the caliper would not release unless you opened the bleeder. Instead of opening the bleeder, crack the line at the caliper. If the pressure releases, tighten it back up and try again but this time crack it at the master cylinder. If it doesn't relieve the pressure, I would replace the brake hose.

I don't think blowing air through it is a good test.

Thank you for the idea! I will try that next.

Most likely just a bad master cylinder piston seal or blocked return valve hole.

Thank you all for the idea to check the brake line with fluid. I did so last night and I'm 80% sure enough it is the brake line. I have ordered a new line and will report back once I am 100% confirmed the solution is fixed. I never would have thought the line would collapse or a flap would cause a one way valve. When I blew air through the line both ways and it worked I assumed the line was fine.

Thanks again.

Make sure the pedal fully retracts off of the master cylinder. If it's adjusted too tight, it won't allow fluid to return.

Got a new brake line installed but the caliper piston still won't go back in. Closer inspection shows that the piston was at askew so I pressed it back in with a vice. I finally got to noticing the exterior piston seal is shredded and mostly gone. Looks like the next move is a new caliper or a rebuild.

Ahhhh that sucks the hose didn't take care of it. But the caliper is an easy fix. You can get the rebuild kit for $18 and it comes with all new seals and pad slide pins. You can get the piston seperate if needed too. But as long as it's not damaged, cleaning it up with a scotch brite pad is usually sufficient. I just had to do mine a couple months ago, it's super easy. Just make sure everything is super clean and get the new o-rings good and wet with fresh brake fluid before pushing the piston back in

If you need to use an air hose to push the piston out of the caliper, do it slowly and with only a few psi in the compressor. I shot mine out like a bullet the first time I did it haha it was sketchy.

Those rebuilds are pretty straightforward, hope that does it for ya!

Had the same the exact symptoms on my recently acquired 96 KDXKDX 200. The PO wasn't too big on routine maintenance . The caliper clearly needed to be rebuilt. However, the brake pin we're so stripped and seized that I couldn't remove it with my trusty ez-out. So, I cut to the chase and purchased a used one ebay for 39.00. Removed the old one, cleaned and installed the new used one, bled the brakes and now it's working fine.

The rear caliper rebuild kit didn’t fix it. I swapped the original master cylinder for a used one I bought and now it works. Problem solved but I don’t know why and I don’t care anymore. Yay

Willbilly wrote:The rear caliper rebuild kit didn’t fix it. I swapped the original master cylinder for a used one I bought and now it works. Problem solved but I don’t know why and I don’t care anymore. Yay

Good stuff, Willbilly.

Willbilly wrote:The rear caliper rebuild kit didn’t fix it. I swapped the original master cylinder for a used one I bought and now it works. Problem solved but I don’t know why and I don’t care anymore. Yay

Return hole in the master was probably plugged up. Glad you got it fixed.