Pirate 4x4 banner

1 - 8 of 8 Posts

·
Registered
Joined
·
2,036 Posts
Discussion Starter #1
Ok, so my peddal drops to the floor I pump and pump and pump and get a little preassure then as I hold it it drops to the floor.....mastercylinder...right! Nope I get a new master (the master is good) and now it does the same thing in fact its worse because no matter how much I pump it never builds preasure. there are no leaks! so I havent blown a wheel cylinder. If the drums where this out of wack Im sure I would have over extended the wheel cylinder and blown it. The pads are new. The shoes are 1 year old. There are no soft lines any where on the truck just hard lines and steel braided....

What say Pirate?


Oh yes i bled the master:flipoff2:
 

·
Registered
Joined
·
1,016 Posts
Ok, so my peddal drops to the floor I pump and pump and pump and get a little preassure then as I hold it it drops to the floor.....mastercylinder...right! Nope I get a new master (the master is good) and now it does the same thing in fact its worse because no matter how much I pump it never builds preasure. there are no leaks! so I havent blown a wheel cylinder. If the drums where this out of wack Im sure I would have over extended the wheel cylinder and blown it. The pads are new. The shoes are 1 year old. There are no soft lines any where on the truck just hard lines and steel braided....

What say Pirate?


Oh yes i bled the master:flipoff2:
We had a guy lose all pressure on our last trail ride, after replacing the master cylinder he still had no pressure... Here's what ended up being wrong with his:

it turned out to be the regulator that mounts under the master cylinder...the one thing that I did not have spare parts for. Figures. Apparently, the mechanic here took it apart, cleaned it, and reassembled it and now everything is working well again! He was telling me that alot of times when you replace the master cylinder, that regulator needs to be cleaned out of the old fluid and basic gunk. For those of you looking at doing a master cylinder change....keep that one in mind!

I'd make sure to check that if you haven't already.
 

·
Registered
Joined
·
1,557 Posts
Sounds like air in the system, if in fact your "new" MC is OK.
Assuming:shaking:you properly bench bleed the new MC, I'd suggest you start capping off each circuit until you discover where the problem lies.
Start by plugging the rear line before it goes to the rear-axle "T"; pedal should be spongy (assumes problem exists in the other circuit).
Then plug the front circuit so that you can isolate the problem.
You may want to start by plugging both MC ports to insure you have a good MC/bleed; pedal should be rock hard.
 

·
Registered
Joined
·
595 Posts
I know on the 80's fords, they have a similar problem, and it's ussually the rear abs vavle messing up.
 

·
Registered
Joined
·
2,036 Posts
Discussion Starter #5
We had a guy lose all pressure on our last trail ride, after replacing the master cylinder he still had no pressure... Here's what ended up being wrong with his:

it turned out to be the regulator that mounts under the master cylinder...the one thing that I did not have spare parts for. Figures. Apparently, the mechanic here took it apart, cleaned it, and reassembled it and now everything is working well again! He was telling me that alot of times when you replace the master cylinder, that regulator needs to be cleaned out of the old fluid and basic gunk. For those of you looking at doing a master cylinder change....keep that one in mind!

I'd make sure to check that if you haven't already.
Huh thanks...I didnt see any regulator but I will look again.
 

·
Registered
Joined
·
2,036 Posts
Discussion Starter #6
Sounds like air in the system, if in fact your "new" MC is OK.
Assuming:shaking:you properly bench bleed the new MC, I'd suggest you start capping off each circuit until you discover where the problem lies.
Start by plugging the rear line before it goes to the rear-axle "T"; pedal should be spongy (assumes problem exists in the other circuit).
Then plug the front circuit so that you can isolate the problem.
You may want to start by plugging both MC ports to insure you have a good MC/bleed; pedal should be rock hard.
I blocked off the MC and the peddal is rock hard. I didnt want to strart blocking off components (calipers, wheel cylinders, LSPV) before I threw this thread out there because its a pain in the ass and I have to re bleed every time I do it. But it is certainly in my future.
 

·
Registered
Joined
·
52 Posts
I'm going to assume that there's no signs of leakage from around the boots on the calipers, correct? And also, have you checked the fittings on your ABS pump to see if its gone out? Does that year still have a vacuum booster? Is the fluid level in the resevoirs on the master cylinder changing at all after the pumping?
 

·
Registered
Joined
·
2,036 Posts
Discussion Starter #8
Well for future searchers.

After isolating each and every component I found that the proportioning valve was bad. I grabbed one from a junk yard and it was also bad so I just replaced it with a union-t and away I went they work great. the next time it rains I will take the truck out and make some hard stops to see if the the rear locks up.

All I wanted to do was bleed the brakes and it snow balled into findinf the following things wrong with my brakes

master cylinder
proportioning valve
wheel cylinder
caliper
both adjusters in the drums

:shaking:
 
1 - 8 of 8 Posts
Top