Hyster 120XL3:
Air in Brakes

S120XL2S
D004D11220Y
Hi I am new to the forum as well as forklifts in general so please bare with me if I start to Ramble and thank you in advance for any help that you offer me.
Last Friday the operator brought me the lift with no brakes
so I did an inspection found no external leaks and the fluid level in the reservoir was full.
so next I bled the wheel cylinders and master cylinder got lots of air bubbles kept bleeding till all air bubbles were out. I test drove it around picking up loads starting and stopping had no issues sent it back out to the line.
Today it came back with no brakes again.. and again the system is full of air with no external leaks so I am at a loss for what to test next. I dont want to just throw parts at it I actually want to find out what is causing the issue and then fix the issue.
Any help you can offer me would be amazing
  • Posted 19 Jun 2015 05:18
  • Discussion started by diesel_chick87
  • Oregon, United States
Showing items 1 - 7 of 7 results.
Update: got everything up and running the wheel cylinder were shot thank you for all the help
  • Posted 21 Jul 2015 03:36
  • Reply by diesel_chick87
  • Oregon, United States
the axle flange should have threaded holes in it, use the axle bolt threaded in to that to pull the axle, clean the surface and apply a sealant when reassembling
  • Posted 30 Jun 2015 22:35
  • Reply by don_a
  • Vermont, United States
loosen the nuts on the wheel but leave them on
then take a large sledge hammer and wack the edge of the wheel if the wheel is hard to get off.
as for the axle leave the bolts on and do the same thing, loosen them but dont remove them, then take a hammer and smak the axle plate and it should pop loose.
Don't hit it extremely hard but give it a good bump a couple times
it will pop loose.
You might want to deadjust the shoes first too before attempting to remove the drum, if they are adjusted out it will be alot harder to pull off.
And being a large truck those drums are heavy so BE CAREFUL, get some help :o)
  • Posted 30 Jun 2015 08:47
  • Modified 30 Jun 2015 08:50 by poster
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
UPDATE: so I rebuilt the master cylinder the seals were shot and there was a little bit of rust in places got everything cleaned up and cleaned up the booster (it was in good shape) and I am still having issues (except no air when I bleed the master cylinder) so I am moving down the the wheel cylinders and am going to do a full brake job..... if I can get the axle unstuck from the hub
  • Posted 30 Jun 2015 06:35
  • Reply by diesel_chick87
  • Oregon, United States
when I bleed the wheel cylinders its fluid then air when i bleed the master clylinder its air then bubbly fluid I am going to pull the master cylinder today and rebuild it Thank you guys for your help
  • Posted 20 Jun 2015 01:04
  • Reply by diesel_chick87
  • Oregon, United States
only 2 places it can pull air in at
-master cylinder
-wheel cylinders
normally...
unless there is a crack in a line or a fitting leaking somewhere

being an XL2 model it has some age on it
my guess is to pull the master cylinder boot back and see if there is any fluid inside the boot, also pull the wheels and check the wheel cylinders.

AND... even if you do this and see no fluid present it still can pull air in if the MS plunger seals or wheel cylinder seals are dried out from age.
when they get old they may shrink up or just be worn enough to allow air to get sucked in when the pedal is released, therefore is where the air is coming from.

Checking the lines for leaks is a bit tricky though, you'll need a pressure bleeder to do this to apply pressure, if there are any cracks or loose or damaged fittings the pressure will make it show up.
If you find no issues during that then the problem has to be in the seals.
  • Posted 19 Jun 2015 21:18
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
When you bleed it, does the air start to come out as soon as the wheel cylinder is cracked open? If so, test both sides and figure out which wheel cylinder is letting the air in. I've come across this twice in my 30 years of forklift repair. Somehow, it can get in the wheel cylinder. If the air isn't in the wheel cylinder as soon as you open the bleeder then it must have a problem further up somewhere.
  • Posted 19 Jun 2015 20:21
  • Reply by mrfixit
  • New York, United States

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