FZJ80 brake bleeding hell

Brian894x4

Explorer
The brakes on my '95 FZJ80 were a tad mushy, so I thought I'd bleed and see what happens....

I spent half the day yesterday and half the day today bleeding...and bleeding...and bleeding. I've got the clearest and cleanest brake fluid I've ever seen, but not only do I still have mushy brakes, now I have brakes that go almost (although not quite) to the floor, when the engine is turned on. With the engine off, the pedal feels OK, although when I really stand it, it's pretty low. I'm pretty sure it's not drivable at this point. However, it was perfectly drivable before I started messing with bleeding the darn things.

I've followed the FSM to the letter again, and again. Even did the master cylinder several times. At this point, I'm wondering if my master cylinder was going bad and bleeding the brakes just caused it to go over the edge somehow or if I just need to keep bleeding, because I still have air in the system.

I'd certainly appreciate any insight as to why it is so difficult to get air out of the system, compared to other rigs, assuming that's my problem. I thought maybe the ABS was trapping air, but I've read this problem is occures on the FJ80s too. My other theory is that some how the return line from the LSVP is trapping air and not letting it out.

The FSM says to "bleed the by-pass pipe", but makes no mention of what exactly that is. I'm guessing they are referring to the LSVP, which I've definately bleed over and over again. But I would sure love to know if they mean something else and I'm missing something.
 

RAM5500 CAMPERTHING

OG Portal Member #183
Hey Brian

I also had a very hard time bleeding the brakes on my 80, for some reason, it took A LOT longer then most rigs to get it dialed in. Weird, i have read the FSM several times and dont recall any mention of a "bypass pipe" maybe thats my problem! :D

Sounds like you have done all of the usual stuff.

I will bet my $ on the MC, although you VERY rarely hear of those going out on these trucks. If all else fails, i suggest "Bench" bleeding the Master Cylinder and trying the whole process over again before you go out and buy a new one.

I ended up going with the one person speed bleeders from Napa and they work great! The first time i bled my brakes, some really gnarly crap/goo came out of those lines.

My .02
 

Grim Reaper

Expedition Leader
Is it on jack stands with the rear wheel dangling? The LSPV will make it feel like doo doo sometimes. The rear brakes are the majority of brake feel. Put it at ride height and see how it feels.
Got a vacuum pump? Pull a vacuum on the master reservoir for a couple hours.
 

Mlachica

TheRAMadaINN on Instagram
Oh man, I hope you're able to figure it out. I saw the nipple at the LSPV but only used the four corners to bleed.

I didn't refer to the fsm, I just had somebody at the peddle and pumped it until clear fluid came out (while keeping reservoir full). Once I felt it was good enough, he depressed the peddle until I closed the nipple. And did this at every corner.

Just make sure you tell him to let off the pedal before you loosen the next valve, or you might get shot in the face - like somebody I know :oops:
 

Brian894x4

Explorer
Well, I have the axle on jack stands so the LSVP is sitting normally. I'm going to try something different tonight, based on some stuff I saw on Mud.

I'll bleed using the pedal method with the engine on. I have a feeling this might be the little known trick to fix the LC80 bleeding problem, but we'll see.

I'll post results when I'm done.
 

asteffes

Explorer
Here's the procedure I always follow on every car/truck I work on. It requires a helper and is the best way I know of to bleed brakes.

Helper gets in the car, turns key on, and maintains pressure on the brake pedal until told otherwise.

You take position at one corner of the vehicle with wrench for bleed screw.

Open bleed screw for two seconds.

Close bleed screw.

Tell helper "cycle," as in raise the brake pedal and again maintain pressure.

Open bleed screw for two seconds.

Close bleed screw.

Cycle.

Repeat 5-6 times. Check fluid level.

Tap caliper with rubber mallet to dislodge any air bubbles.

Bleed again, as needed, until no more air or debris comes out.

Move to next corner.


This method works well because there's no guesswork as to when to stop pushing the pedal. Your helper just maintains pressure until you say "cycle." You are certain to open and close the bleed screw while the fluid is under pressure, giving no chance for air to enter the system.

Hope this works for you.
 

Brian894x4

Explorer
Thanks for the tips. Good info.

I'm a step closer, but still no dice.

I finally got a nice steady stream of fluid come from each corner with no bubbles, but the LSVP is still giving me headaches. Still got bubbles and pedal still goes to the floor.

I ran out of brake fluid, so I'll have to continue tomorrow. I used 3.5 full size cans today and total about 7-8 cans of brake fluid to get to this point. But now that I know what it looks when there are no bubbles, I at least know what to shoot for with the LSPV. I'm a little confused why I have no bubbles at the rear brakes, but still have air at the LSVP. I"m guessing it's the return pipe from the LSVP that still has air in it. I also wonder if that darn air in the return pipe and the fact that most people and brake shops don't bother bleeding the LSPV, much less use 8 cans of brake fluid, if all these complaints I hear about the 80s braking system might be nothing more than an improperly bleed brake system with air still trapped in the LSPV and return pipe.

By the time this is done, it's going to one seriously flushed system. I did test the master cylinder using the method where you put steady pressure on the pedal and see if it drops over time. It doesn't, so while the brake pedal does go to the floor with full pressure and the engine turned on, I'm think it's still just air in the system.

I also went to change the oil today and it took me about an hour to get the oil filter off, thanks to who ever the PO had change the oil over tightening it. Not a good weekend. But, I figured out if you just unbolt the power steering resevor, getting to the oil filter is super easy, assuming it's not overtightened.
 

HongerVenture

Adventurer
One other item that may come in handy...
Import_Power_Bleeder_Small.JPG


It is the Motive Products Power Bleeder. I picked one up used (only used once) off of Yotatech and absolutely love it. It makes bleeding the brakes a cinch. My wife doesn't have to pump the brake pedal and the system is under constant pressure. BTW, I don't have any interest in them, it has just REALLY made the job easier.

One other detail... when bleeding brakes by pumping the pedal you can cause the brake piston to travel further in the cylinder than it normally does. If there is corrosion or debris in that area, it can damage the seal on the piston. While this is typically a problem only in older vehicles or those with a poorly maintained brake system, it is a consideration. Was your fluid extremely discolored before you started?

Brian, are you bleeding the LSPV last, after all four wheels? I know for my truck the LSPV has to be bled last. Since you have the FSM, I'm sure you are but just thought I'd ask to be sure.

Hope you get it worked out.
 

Brian894x4

Explorer
I've heard that product mentioned a few times with good comments. If all else fails, I may try to find one. I'll definately consider one if I have to do this again.

The FSM is very vauge about the brake system on a number of different points. They only mention start at the cylinder with the longest line first and that's it. Then the second sentence says, bleed the brake return pipe, but doesn't indicate what that is.

I assume that's the LSPV. It definately doesn't mention bleeding the LSVP by the name we all know it as, or in what order. However, since the LSVP feeds the back brakes, I assumed RR, LR then LSPV, then front. However, I've been doing it so much that I've gone out of order a number of times.

Now that all four wheels bleed good, but not the LSVP I'm kind of confused, except that I think the air coming out of the LSVP nipple is actually from the return pipe between the LSPV and ABS. If that's the case, then it might make sense that the LSPV needs to be done last.

As for the color, it was pretty good. I don't "think" I've damaged the master cylinder, but I'm heard of that being possible. I know I still have air in the LSVP line as I can see bubbles when I bleed.

We'll see.......
 

Grim Reaper

Expedition Leader
The line at the LSPV is a feed back line from the front circuit.

It works against a diaphragm in the LSPV. No fluid exchanges. The brakes should bleed in the same order as your 89. Four wheels then LSPV
 

Brian894x4

Explorer
3.5 more full size cans and about 4 hours of my life I'll never get back and I still haven't fixed the problem.

I think I've used about 12 cans so far over the last 4 days. Or about 3 gallons of brake fluid to flush this POS out.

I have good solid fluid from all four wheel cylinders, and I finally have pretty good solid fluid coming from the LSPV, but I still get an occasional bubble, so I still have air related to the LSPV. The big problem is the brake pedal still goes almost to the floor when the engine is on. When it's off, it feels nice and firm, much better than even before I started bleeding. So, I can't figure that out. I guess I still have significant air in the system...somewhere.

I've done the master cylinder leak down test and when I hold firm pressure on the pedal, it does not move, so I don't suspect the Master Cylinder is bad.

At this point, I'm debating whether I want to keep bleeding the LSPV or just drop the darn thing off at the dealer and let them bleed it. I may try to find one of those before mentioned Power bleeders here locally. I'm in no mood to order something and wait for it. I just want to be done with this.
 
Last edited:

DaveInDenver

Middle Income Semi-Redneck
HongerVenture said:
It is the Motive Products Power Bleeder. I picked one up used (only used once) off of Yotatech and absolutely love it. It makes bleeding the brakes a cinch. My wife doesn't have to pump the brake pedal and the system is under constant pressure. BTW, I don't have any interest in them, it has just REALLY made the job easier.
I have one of those Power Bleeders. It works well, I've used it for both brakes and clutch on my truck and our Civic. The only issue I've had so far is getting the cap on the clutch master takes some fiddling. Once you get it attached and sealed, works really well. I've heard some people speak negatively about it because the brake fluid and pressurized air are not separated by a membrane. This is common on pro bleeders that use shop air and apparently it's possible in theory to cause air to dissolve into the brake fluid, which then introduces air into your brakes. I dunno, I don't seem to have an issue like that. Anyway, this makes brake bleeding truly a one man job.
 

Brian894x4

Explorer
Grim Reaper said:
Have you drove it yet?

It might put you through the windsheild. Might have a very light peddle.

You make a good point. I might be over reacting. I'm going to bleed it a little bit longer, since I was making progress and then test drive it. It might be fine after all. For some reason I assumed that the brake pedal shouldn't go down that far, but in driving other cars, it does.
 

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