86 Husky 400 WR Brake Bleed Question.

Hi,

I just got back my master cylinder from a dealer who rebuilt it. I tried to bleed it today with no luck. When I open the bleeder I do have some fulid come out. No pressure though. I put a clear line on the bleeder with it open and I don't get any fluid that comes through. I do see air bubbles in the master cylinder when I pump it. I have probably pump it 100 times. Any tips on this?

make sure there is no loop in the line
by this I mean a place air can get stuck from a high place in the line
remove the master if you have to and elevate it
do a gravity bleed, if you have any pressure on the lever, squeeze it and crack the line at the master tighten it and see if it's better
if you have bubbles in the master it's your bypass not working correctly as I recall
on my KTM had that problem, removed the brake line and put my finger over the outlet to be sure I had pressure

and second question round or rectangular reservoir?
early like an 85-86 style or later like 87-88 type?

It's the rectangular Brembo master cylinder.

I believe on two occasions I have resorted to removing the caliper and routing the line so it could be hung higher than the master cylinder. Wedge something between the pads and bleed it in that position.

I can't answer if there is something wrong with your master cyl. from your description,
but I can give a friendly tip to use a Mityvac handpump for bleeding brakes. I got the cheapest one in plastic and it works great.

Have you tried strapping the lever back to the handlebar with a zip tie or bungee cord?
This has worked for me many times if left overnight as long as the hose never gets higher than the master cylinder.

I have one from the 80's when they were made of aluminum. I made the mistake of loaning it to a friend and not checking it out when he returned it. A seal blew up from him drawing hydraulic fluid thru the pump. So when I needed it 10 plus years later, I had to buy the plastic unit that will not fit in the case for the original.

remember, no good deed goes unpunished

When I had that problem on my 430 I seem to remember I forced the fluid up from the bleed nipple up into the reservoir using a syringe. It still goes slack if not ridden for a couple of months so I tend to leave the lever bungied back to the bars!

another vote for the mityvac...quick and easy work for any bleeding.

yyou probably have the zinc silverline 4000 like i do with the finger grooves on the handle. you can still rebuild these.
they can still be bought in metal..

heres the newer zinc version

I have installed new or rebuilt master cylinder in automobile type stuff and the instructions are to bleed (pump, circulate) it back into the reservoir first, then attach it in a permanent fashion.

Brake fluid should be changed, not that I do it right, that plastic one looks more useful for changing fluid in things. Larger volume pump.

When I checked on the rebuild parts, they were more expensive than the plastic version I picked up. I will rebuild the original as it is still dear to me. At least I have something that works but I always prefer the way older tools were made

like the new crap Craftsman is trying to pass off as tools. OLD is where it at in the tool department.

If you're still having issues consider reverse bleeding. This is done by forcing fluid into the system through the caliper bleed valve.

Youtube how to. Link is at the bottom of the page.


View: https://www.youtube.com/watch?v=6UCNWfA7dVs

Thanks I will give it all a try. Got real busy have not had a chance to work on it.

Face it, its a black magic thing....

We found the problem. Piston in the brake caliper. We're sized. Thanks for all the help.