Brake mystery in a HJ60-long, but need advice! (1 Viewer)

[Jan-78FJ40]

I am putting this in the international section, since the vac pump could theoretically play a role here-I'll link it in the 60 section to here.

I am having some brake problems that we can't figure out. The truck is a 1984 HJ60, originally from central america.
Here are the symptoms: The brakes work just like they should, when used frequently. However, when driving for a while without braking, the pedal will have very little resistance till it is almost at the floor. One pump brings it up to working order again. Even a quick tap with the foot brings it to proper working order.

Here is what we have done:
-Tested vacuum from the pump-the vac is fine
-the vac tank holds vacuum
-the booster holds vacuum, and was replaced, since I first thought it might be the culprit
-the calipers are new
-the rear cylinders are new
-the hardware in the rear brakes are new, except the drums, the cable with the 2 stop washers on it, and the adjusters
-the system has been bled many times
-the brake master is new and has been bled
-there are no leaks anywhere
-the pedal is not spongy
-the pedal height and freeplay are adjusted to specs
-the booster test works to specs

-yesterday, when driving home from Michael's garage, the passenger rear side overheated.

-the frons brake discs are NOT new as well


I am at a loss here and need help-this needs to be fixed!

thanks for your advice!
Jan

 

[David*BJ70]

still air in the system...

 

[Jan-78FJ40]

still air in the system...

wouldn't that lead to a spongy pedal?
the pedal is firm, once working.
and where would the air be? we've bled this system numerous times...

thanks
j

 

[NocalFJ60]

I would start with replacing all the soft lines if you haven't yet. They are cheap from dealership.

Talked about it in this thread

https://forum.ih8mud.com/showthread.php?t=79304

 

[Jan-78FJ40]

I would start with replacing all the soft lines if you haven't yet. They are cheap from dealership.

Talked about it in this thread

https://forum.ih8mud.com/showthread.php?t=79304

Thanks Doug. The soft lines have been replaced by stainless steel lines.
Jan

 

[NocalFJ60]

You replaced the soft line going down to the rear axle from the frame with a hard line?


Replace the rear cylinder again on the wheel that is acting up. If the brakes is burning up, it would seem there is either a mechanical issue with the cylinder which is not allowing it to release and uncompress or the brake fluid is putting pressure on the cylinder.

Jack up the bad wheel and have some one push on the brakes. Try and spin the wheel and see if it locks up. Then have them release the brakes and immediately try and spin it and see if there is a restriction.

Goodluck

 

[Jan-78FJ40]

You replaced the soft line going down to the rear axle from the frame with a hard line?


Replace the rear cylinder again on the wheel that is acting up. If the brakes is burning up, it would seem there is either a mechanical issue with the cylinder which is not allowing it to release and uncompress or the brake fluid is putting pressure on the cylinder.

Jack up the bad wheel and have some one push on the brakes. Try and spin the wheel and see if it locks up. Then have them release the brakes and immediately try and spin it and see if there is a restriction.

Goodluck

Thanks, I'll try that.
Yes, the soft line to the axle has been replaced.
Do you know if the rear drums for a full floater are the same as for a semi floater?
J

 

[lowtideride]

Sounds like you still have air in the system there bud. I hate bleeding brakes but I use a gooood amount of fluid when i bleed them. Tape the calipers when you are bleeding the brakes to help get air bubbles out.

 

[60wag]

-yesterday, when driving home from Michael's garage, the passenger rear side overheated.

-Jan

When you replaced the booster, did you confirm that the pushrod between the booster and the master is adjusted properly? That could cause the breaks to drag a bit and cause the overheat. The overheat MIGHT cause the fluid to boil and allow the pedal to drop. Its a long shot but worth checking.

 

[Jan-78FJ40]

When you replaced the booster, did you confirm that the pushrod between the booster and the master is adjusted properly? That could cause the breaks to drag a bit and cause the overheat. The overheat MIGHT cause the fluid to boil and allow the pedal to drop. Its a long shot but worth checking.

Thanks, I will check that.
The pedal drops was happening before I replaced the booster, unfortunately. I hoped it would be the booster, but it was'nt.
Jan

 

[Tapage]

sometimes when we bleed with our usually method the system we wornout the rubers seals on the master. The proper way to bleed the system is with a bleeder, not using the pedal ..

Is a cheap option I thought ..

 

[Jan-78FJ40]

Update: I had an exhaust put on today (for the new turbo), and asked the guys to bleed the system with a bleeder, not just pumping. They did that, there was very little air in there, but the pedal started sinking again afterwards.

Their suggestion (which is exactly what Wayne predicted-ThanksWayne) was that the master is dysfunctional. Well, the master is a new one, but new parts can be bad too. So I'll put another new one on on sunday, and report back.

Thanks guys,
Jan

 

[KOZ_73]

I'll chime in here because i had this exact thing happen to me on my BJ70. You mentioned that your rear passenger brake overheated, well this happened to me and i had the exact same symptoms. Turned out that when i had my rear brakes done, the piston was sticking, causing my brakes to be constantly on and boiling the brake fluid. The result of this was that i was able to floor the brakes, I had to pump once or twice to get braking ability back. I suggest you take it for a drive and check how hot your rear passenger rim is getting, mine got so hot from the brakes that when i spit on it it sizzled. DONT touch it with your hands.

 

[Tapage]

Their suggestion (which is exactly what Wayne predicted-ThanksWayne) was that the master is dysfunctional. Well, the master is a new one, but new parts can be bad too.

Jan .. and you keep your invoice .. this part have warranty .. ?

 

[Jan-78FJ40]

I'll chime in here because i had this exact thing happen to me on my BJ70. You mentioned that your rear passenger brake overheated, well this happened to me and i had the exact same symptoms. Turned out that when i had my rear brakes done, the piston was sticking, causing my brakes to be constantly on and boiling the brake fluid. The result of this was that i was able to floor the brakes, I had to pump once or twice to get braking ability back. I suggest you take it for a drive and check how hot your rear passenger rim is getting, mine got so hot from the brakes that when i spit on it it sizzled. DONT touch it with your hands.

Thanks for the information! I'll check into that. Just ordered new adjusters for the rears, and I still have 2 more new cylinders. I'll put those on on sunday...

thanks
Jan

 

[Jan-78FJ40]

Jan .. and you keep your invoice .. this part have warranty .. ?

it won't be a problem to return, thanks,
jan

 

[dieselDaryl]

Jan,

I've been having brake problems in my HJ61 (88) recently as well. My pedal doesn't drop easily to the floor like yours, but it isn't as firm as I think it should be either. I can still 'bottom it out' while stopped with the engine running or on the highway in panic stop conditions. I cannot lock the brakes up very easily on gravel. The pedal is relatively firm, but with enough pressure I can definitely reach a hard point at the bottom of its travel.

Now I know everyone is going to tell me that I've got air in the system and should bleed it, but I've bled it a over and over and over. I've had other people bleed it. I always bleed from furthest wheel to closest wheel. There is no LPSV that I can see to bleed.

I've done the following:
-Run at least 4L of fluid through the system (using one man bleeder and also doing it with a helper)
-Replaced the rear wheel cylinders
-Turned the rear drums
-Replaced the pads and shoes
-Replaced the Rotors
-Replaced the Master Cylinder (bench bled it first)
-Adjusted the rear brakes both with the e-brake cable (bellcranks are not seized) and manually through the backing plate.
-Adjusted the pedal according to the FSM
-no Leaks
-No oil on rotors and/or drums


Jan, have the new rear cylinders fixed your problem? I've already gone down that road and it didn't make a difference for me, but sounds like it may fix your problem. Don't forget to pull the e-brake handle about 50 times to get the new clyinders adjusted properly.

I am at my wits end with this. The brakes are okay but only at about 70% of what I remember them being a year ago. My gut tells me that its air in the system but for the life of me, I can't find where it would be. I've also thought maybe the booster has gone bad or needs adjustment. If yourself or anyone else has any ideas, I'd appreciate it greatly.

 

[bigbrowndog]

Jan,

I've been having brake problems in my HJ61 (88) recently as well. My pedal doesn't drop easily to the floor like yours, but it isn't as firm as I think it should be either. I can still 'bottom it out' while stopped with the engine running or on the highway in panic stop conditions. I cannot lock the brakes up very easily on gravel. The pedal is relatively firm, but with enough pressure I can definitely reach a hard point at the bottom of its travel.

Now I know everyone is going to tell me that I've got air in the system and should bleed it, but I've bled it a over and over and over. I've had other people bleed it. I always bleed from furthest wheel to closest wheel. There is no LPSV that I can see to bleed.

I've done the following:
-Run at least 4L of fluid through the system (using one man bleeder and also doing it with a helper)
-Replaced the rear wheel cylinders
-Turned the rear drums
-Replaced the pads and shoes
-Replaced the Rotors
-Replaced the Master Cylinder (bench bled it first)
-Adjusted the rear brakes both with the e-brake cable (bellcranks are not seized) and manually through the backing plate.
-Adjusted the pedal according to the FSM
-no Leaks
-No oil on rotors and/or drums


Jan, have the new rear cylinders fixed your problem? I've already gone down that road and it didn't make a difference for me, but sounds like it may fix your problem. Don't forget to pull the e-brake handle about 50 times to get the new clyinders adjusted properly.

I am at my wits end with this. The brakes are okay but only at about 70% of what I remember them being a year ago. My gut tells me that its air in the system but for the life of me, I can't find where it would be. I've also thought maybe the booster has gone bad or needs adjustment. If yourself or anyone else has any ideas, I'd appreciate it greatly.

Have you had your booster checked out? Would pay to pull the vacuum hose off the vacuum pump and check that it is working ok if it is ok at the pump replace the hose and do the same at the booster.I suffered similar problems with my truck a while back. The booster was actually still holding a vacuum but the unit was not functioning. I had bled all wheels and the load proportioning valve and replaced everything.cheers

 

[Jan-78FJ40]

Jan,

I've been having brake problems in my HJ61 (88) recently as well. My pedal doesn't drop easily to the floor like yours, but it isn't as firm as I think it should be either. I can still 'bottom it out' while stopped with the engine running or on the highway in panic stop conditions. I cannot lock the brakes up very easily on gravel. The pedal is relatively firm, but with enough pressure I can definitely reach a hard point at the bottom of its travel.

Now I know everyone is going to tell me that I've got air in the system and should bleed it, but I've bled it a over and over and over. I've had other people bleed it. I always bleed from furthest wheel to closest wheel. There is no LPSV that I can see to bleed.

I've done the following:
-Run at least 4L of fluid through the system (using one man bleeder and also doing it with a helper)
-Replaced the rear wheel cylinders
-Turned the rear drums
-Replaced the pads and shoes
-Replaced the Rotors
-Replaced the Master Cylinder (bench bled it first)
-Adjusted the rear brakes both with the e-brake cable (bellcranks are not seized) and manually through the backing plate.
-Adjusted the pedal according to the FSM
-no Leaks
-No oil on rotors and/or drums


Jan, have the new rear cylinders fixed your problem? I've already gone down that road and it didn't make a difference for me, but sounds like it may fix your problem. Don't forget to pull the e-brake handle about 50 times to get the new clyinders adjusted properly.

I am at my wits end with this. The brakes are okay but only at about 70% of what I remember them being a year ago. My gut tells me that its air in the system but for the life of me, I can't find where it would be. I've also thought maybe the booster has gone bad or needs adjustment. If yourself or anyone else has any ideas, I'd appreciate it greatly.

Hi Daryl,
here's the update: I had the brakes bled by a shop, and there was no air in there.
So I changed the master on sunday, and that fixed the problem almost completely. The brakes are still not as good as in my BJ70, but the pedal does not drop anymore.
So my advice is to look at the master again. I did not think it could be at fault, because it was a new one, but obviously I was wrong.
regards,
Jan

 

[dieselDaryl]

Hi Daryl,
here's the update: I had the brakes bled by a shop, and there was no air in there.
So I changed the master on sunday, and that fixed the problem almost completely. The brakes are still not as good as in my BJ70, but the pedal does not drop anymore.
So my advice is to look at the master again. I did not think it could be at fault, because it was a new one, but obviously I was wrong.
regards,
Jan

Hmm.. Mine was a 'new' master Clyinder (Alstrom P9885 posted elsewhere in the forums)

I've heard of people needing to try several master cylinders. Maybe I will go for OEM ($220) or so... But I will check the booster operation first. I've done all of the tests in the manual.. ie pedal sinks when I start the truck, etc...

Glad to hear that your issue is resolved..