bleeding brakes

[FarmerBrown5]

Bleeding the rear brakes on my 92 Comanche. Had a line blow and had it replaced. Can you bleed the brakes when the truck is on a two post lift? I still have the proportioning valve and I did not know if the valve completely extended would create a problem while bleeding the rear brakes. Any info is appreciated

[johnj92131]

Short answer from me:  I simply do not know!   BUT, can you pull and hold the valve lever in the up position with a strap?   Would that solve your issue/question?

 

 

[HOrnbrod]

I also still have the load sensing valve (always will) and have never done anything special, like the procedure in the FSM, to bleed the LSV and it's associated brake lines. Always have had a nice firm brake pedal and good braking. So I wouldn't worry about it as long as you have good braking.

[Pete M]

the factory procedure is in the DIY forum (link in my sig)

 

 

[FarmerBrown5]

10-4. Was not sure if being on a lift in the air mattered or not. Doesnt sound like it does. Thanks all!

[Eagle]

4 hours ago, HOrnbrod said:

I also still have the load sensing valve (always will) and have never done anything special, like the procedure in the FSM, to bleed the LSV and it's associated brake lines. Always have had a nice firm brake pedal and good braking. So I wouldn't worry about it as long as you have good braking.

 

This works fine -- for the normal braking fuction/circuit, which is what your foot feels when driving around. By skipping the FSM procedure for properly bleeding the MJ system, you have no way of knowing if there's air in the rear bypass line. If there is, instead of getting full braking to the rear if the front brakes fail, you'll get mushy rear brakes at best, or posibly nearly no rear brakes at all.

 

The factory specified  that procedure for a reason ...

[HOrnbrod]

Yes, that's how it's supposed to work. I've yet to hear of anyone in an MJ losing their front brakes then have the bypass line provide rear braking. Have you?

[Eagle]

1 hour ago, HOrnbrod said:

Yes, that's how it's supposed to work. I've yet to hear of anyone in an MJ losing their front brakes then have the bypass line provide rear braking. Have you?

 

No. When I lost brakes in my '88, it was the height sensing valve itself that popped, so I still had the fronts. The fact we don't know of it happening doesn't in any way negate the reason the system was designed the way it was, and it doesn't provide me any rational reason for NOT ensuring that the system is properly bled.

[cruiser54]

I've always bled mine the old fashioned way with no issues...ever.

 

That Hobo Freight air operated one man bleeder is the cat's meow though. 

[Pete M]

those of us that live in the rust belt know what it's like to blow out brakelines   I haven't lost the front line in an MJ yet though, just a rear.  lost a front in my dakota though.  a buddy of mine lost a front in his ranger twice in one winter.  (note to everyone: if you lose one, chances are the other is close behind so replace them together)

[HOrnbrod]

10 hours ago, Eagle said:

 

No. When I lost brakes in my '88, it was the height sensing valve itself that popped, so I still had the fronts. The fact we don't know of it happening doesn't in any way negate the reason the system was designed the way it was, and it doesn't provide me any rational reason for NOT ensuring that the system is properly bled.

 

Yes, I agree. If there's a chance that the bypass system might work should a blown front line occur it should be bled. The bypass line is probably clogged up solid though after 25+ years though........

[DesertRat1991]

2 hours ago, cruiser54 said:

I've always bled mine the old fashioned way with no issues...ever.

 

That Hobo Freight air operated one man bleeder is the cat's meow though. 

 

What do you mean?  Do they make a pressure bleeder adapter that fits this thing??

 

[cruiser54]

Nope. It sucks fluid out through the bleeder.

 

 

[Skorpyo]

I used a hand-pump one that my buddy had (looked like this: http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=MITMV8000&source=froogle&kw=MITMV8000&gclid=EAIaIQobChMI492ftYLB1gIVwc0bCh36fwLAEAQYASABEgJRZfD_BwE) to bleed mine and while it worked pretty well we still got a little more air out using the pedal pumping method afterwards.

[Eagle]

7 hours ago, HOrnbrod said:

 

Yes, I agree. If there's a chance that the bypass system might work should a blown front line occur it should be bled. The bypass line is probably clogged up solid though after 25+ years though........

 

That's what happens if you don't bleed it for 25+ years.