| Author |
 Topic  |
|
|
Fredcorvette
New Member
Canada
2 Posts |
 Posted - 12/01/2010 : 08:40:00 AM
|
Hello, I'm new on this forum. I'm original Dutch (Netherlands) but I'm living in Saskatchewan, Canada.
I need some help with information about a 1995 school bus BFord 36pas.
It has the "famous" Lucas Girling park brake system and I now it's a pain to work on. It looks like the back plate's with cylinders and brake shoes on the rear axle are replaced a little while ago. The front brakes are disc brakes.
One of the hoses/lines from the hydraulic pump to the hydraulic manifold from the Lucas Girling park brake system runs hot when you drive the bus. And I mean really hot, it looks like the oil start boiling in the line. You can not tough the line or you burn your fingers. The park brake System works fine and also the hydraulic brakes, the electrical motor kicks in after the engine would stall works fine to. Somebody any idea what wrong?
Will it help to place an transmission cooler in between the line?
Thanks everybody for reading this and the help.
Fred |
|
|
Wolf0r
Top Member
USA
2181 Posts |
Posted - 12/01/2010 : 12:20:44 PM
|
| You have a restriction somewhere. |
“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson |
 |
|
|
Fredcorvette
New Member
Canada
2 Posts |
Posted - 12/13/2010 : 12:04:04 PM
|
Howdy,
A lot of readers but only one answer, Thanks WolfOr. I was thinking about an restriction to, but took the whole thing apart and can't find the problem. Does anyone know if there are manuals (books or Internet) available for this type of Bus, or for this brake system. Or where to buy. Or any technical information what would help to understand this brake system. O-rings and plungers in the hydraulic manifold looking good. I was thinking to check the pressure on any exit from the hydraulic manifold but I have no idea about the pressure different or pressure build up on the exit side of the manifold. Ford dealers around are not much of a help.
Thanks,
Fred |
|
|
|
Wolf0r
Top Member
USA
2181 Posts |
Posted - 12/13/2010 : 1:01:27 PM
|
| I have 1995 Ford dealer manuals and there is nothing in the troubleshooting about high temps. I just figured a restriction would build up heat. They don't list any pressures that I have found. I wouldn't see where it would hurt to add a cooler, the old F-150s used one on their p/s systems on the return side. |
“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson |
|
|
|
BJ Henderson
Advanced Member
USA
280 Posts |
Posted - 12/13/2010 : 2:37:54 PM
|
I assume you checked the filter for restrictions. Another thing to look at is the lines and hoses, especially on the suction side to see if air is getting in somewhere in the circuit. Pressure side leaks are easier to find. Those hoses can collapse internally and block the suctions side of the pump. Other than that, high pressures or low pressures as well can cause overheating in a hydraulic system. Remember the pump creates flow and wherever the work or restriction is creates pressures.
If you have a temp gun, start the thing cold and check for the first place temps begin to rise.
Not sure of pressures never had a need to check them. There has to be some specs somewhere. Without flow rates, you won't know near as much though. |
CMTT,CMAT,CMBT |
|
|
|
bwest
Administrator
United States
3820 Posts |
Posted - 12/14/2010 : 04:55:44 AM
|
It has been a long time since I have worked on one of these systems but I will attempt to help because you are having trouble getting anyone. You need to make sure you have Mercon automatic trans fluid in your system. If you have anything heavier you might have an over heat condition. Now check the pressure between the HR1 valve and the Park control valve to verify you have over 155 psi. I am not sure what the max pressure the book only says make sure it is over 155. Another check my book talks about is the difference in two gauge pressures. One gauge is in the location of the above mentioned and the other gauge is between the HR1 valve and the brake chambers. There should be no more than a 10 psi difference between the two. These two checks are when the system will not engauge so this may be a wild goose chase but at least you know where your at with pressures.
I guess I should have ask what, if anything, the system is doing out of the ordinary other than heat? Is there any noise from the pump? Are there any warning lights on? How does it feel when you press the pedal? Does it feel like there are rocks going through the system?
Like I said, it has been a long time since I have worked on these systems and when I did work on them I did not feel as if I had a handle on them. One time you felt you had the thing figured out then the next time you could have the same symtoms but what you tried before did not cure it. Good luck. |
Bryan |
|
|
| |
Topic |
|
Lucas Girling park brake
