park brake will not disengage

[threelies]

Hey guys, I'm a retired jet mechanic/garbage truck driver/all around fixitifitsbroke that, while home on vacation, told my dad I would look at a truck he bought for his furniture business, I also own a non IDI ford f250 with the same basic engine which has caused me to drink on more than a few occasions. The truck in question is an International 4700 e444 that was bought used and has been sitting up since then with various problems. Unfortunately I don't know the actual year model of the truck but I believe it is between 1995 and 2000.
I've managed to work out all the kinks but one, appearantly the park brake will not disengage and this problem seems to have developed since it's been sitting up. One of the employees said that even though the brakes have never locked up before, when they were released, they seemed to drag for a while before "acting normal" and "didn''t have any power going up hill". I did a stall speed test on the torque converter and it stalls at about 1350 rpm. Oil pressure stays between 48 psi at idle and 55 psi at both stall and at 3000 rpm in Park or Neutral. The engine cold starts within 2 - 3 seconds with little or no valve rattle and no smoke was evident throughout the test, black or white. I mention these things because I think it eliminates or at least reduces the possibility that the lack of power is due to fuel injector(s), fuel line air leaks, or the injector pump. I found no evidence of loose clamps, leaking, broken, or torn turbo hoses or any other turbo related problems. The engine has no fuel or oil leaks (now), runs quiet, and the turbo appears to be functioning normally.
It has juice brakes and the shifter has "pb" annotated next to the park position. It looks like an allison automatic transmission and the park brake is integral to the drive shaft at the rear of the transmission. The brake "knob" looks like what you would expect for air brakes (might have even been yellow once) and passes through the firewall at the far left of the dash to a valve that is attached to the engine side of the firewall. Three hoses go from there to to a valve assembly at the rear of the transmission where three or four other hoses are also attached. Beyond this assembly is a canister that resembles the air canisters on most airbrake systems I've seen on tractor rear brakes and on trailer brakes. A pawl extends out of the opposite end of this canister and attaches to the actuator lever for the brake shoes on the rear of the transmission. The pawl does not move (extend out) as it should when the brake knob is pushed in. I initially thought that it might be frozen in place from lack of use and, with the knob pushed in, tried shifting the tranny from drive to reverse a few times to break it free. I had no luck at that so, with the engine running and wheels chocked, I cracked each line individually at both the firewall valve and the valve assembly at the transmission to check for fluid flow. With the brake knob pushed in I had flow at all fittings. Ultimately I removed the pin that holds the "pawl" and "actuator lever" together in order to release the brakes. Of course the truck has to be chocked all the time now and It can't leave the yard until this is fixed, but it does allow me to move it in and out of the shop in the interim. The only post I found in the forum was about brakes not engaging but mechman spoke of a "switch" that when bad would cause the brakes to not release. I hope that I have given you all the information you need to help me out. If not I would be glad to answer any questions as best as I can.
So now to my questions.
1. Is this "switch" the one with two wires that is screwed into the side of the actuator canister I spoke of?
2. Do you know the proper name for it so that I can get it at the parts house without sounding like a dope?
3. I don't have access to the internet at the shop and it's 50 miles each way. Assuming that this switch doesn't fix the problem, does anyone know of any other tips or troubleshooting measures I can use to narrow down the problem.
4. Assuming that with your help I'm able to get everything working, what is the proper procedure, if any, for adjusting this brake.

Thanks in advance for your help,
Threelies

 

[Racer X 69]

Is this the same truck that a guy was asking why the park brake would not hold on?

Also, Allison automatic transmissions do not have "Park" like an automotive tranny. The "PB" is a position added in recent years to truck automatic transmissions on rigs with hydraulic brakes and stands for Park Brake.

The brake dragging and the truck having low power story from the former owner sounds like the brake was hanging up, and it "freed up" after enough brake lining was worn away to have clearance between the shoes and drum.

That is not a good way to deal with a brake problem. It should have been taken to a qualified shop for diagnosis and repair. (I get that it was before your dad owned the truck)

You likely are going to need to tear it apart and see why the brake is not functioning properly.

 

[threelies]

Thank you racer x 69 for your insightful response. I'm certain that you are well known for being out standing in your field. Actually the guy with the park brake that would not hold was responded to by Mechman with the bit about the "switch" that would cause the brakes to fail to disengage as opposed to failing to engage and it was that quote that I was illiciting a response for with my question 1.
I am well aware that there is no mechanism within the transmission in question that locks the drive train while the shifter is in the uppermost position (which happens to be marked with a "P" to the left of the shifter handle and a "PB" to the right of the shifter handle) My purpose for adding this to my original message was to give additional information, to whomever might be capable of helping me, with as much information as possible.
My entire second paragraph (which is where you end a sentence before the end of one line on the page and start a new sentence on the next line) was devoted to the "brake dragging and low power story" and the things I had done to confirm that neither the engine nor the transmission were the problem but that, since I don't know everything, someone might have other troubleshooting tips that I had not thought of to further confirm the same and that the symptoms described in the "brake dragging and low power story" might be indicative of a specific part that was gradually failing to the point where the truck would no longer move.
Finally, tearing "it" apart is pretty much a last resort for any mechanic, especially before knowing what "it" is, how "it" might respond to being torn apart, and how one might confirm that "it" needs to be torn apart.
All this having been said, you were kind enough to respond to my post, my funny bone thanks you.
threelies

 

[Racer X 69]

One thing I just thought of was the possibility that the actuating cable is corroded inside the sheath, and the cable is not moving freely, and is causing the brake to hang up. You could test this by disconnecting the cable at both ends and see if it moves freely.

 

[bigyellowpete]

u gotta go to the p like it goes prnd321 go to the one that says "p" and when u want to go to a diferent one but your foot on the brake and move the shifter sometimes that shifter has a little button on the side u gotta push thats prolly what your doin wrong your not pushin the button to take it out of park

Really?

Just stop trying to give people technical advice. It's obvious you haven't a clue, or you are just being a douche and looking to get flamed.

 

[Racer X 69]

u gotta go to the p like it goes prnd321 go to the one that says "p" and when u want to go to a diferent one but your foot on the brake and move the shifter sometimes that shifter has a little button on the side u gotta push thats prolly what your doin wrong your not pushin the button to take it out of park

Really?

I worked on medium and heavy trucks for thirty years, a lot of which were equipped with Allison automatics, and not one ever had what you describe.

The shift lever markings were RND321. No park position.

I do understand some of the newer rigs have a "PB" position, for Park Brake, as it apparently is too difficult for some drivers to pull on the park brake lever.

I still think you were dropped on your head as a child.

Maybe you should go back to the sand box and your Tonka Toys.

 

[Private Pyle]

Racer you sound like my uncle whos been a mechanic for a long time.

 

[mechman]

The switch is the one on the dash, it is the same switch used for electric 2 speeds, but mounted on the dash instead of on the gearshift lever. Proceed as follows: under the driver's step is a plastic tank. This is the fluid reservoir for the system. Remove it and dump the water/ATF mixture out and refill with ATF. As outlined in the other post, these tanks will acquire water over time unless the cap is replaced. The chamber(actuator) is just a container with a spring in it that is released by fluid. Exactly like an airbrake chamber, but with fluid instead of air. The switch on it just indicates when adjustment is needed via a dash light. The chambers rarely fail, but may leak, so don't replace it unless it leaks. Near the reservoir is a solenoid/valve combination that is usually the problem. To diagnose, see if fluid goes to the chamber with the button in. If not, replace both valve and solenoid. And yes, racerx69, pb position actually does set the parking brake, hard to believe you worked in the industry 30 years and haven't seen this system. It was very common on medium GM products.

 

[Racer X 69]

And yes, racerx69, pb position actually does set the parking brake, hard to believe you worked in the industry 30 years and haven't seen this system. It was very common on medium GM products.

Most of my experience was with a fleet of electric utility trucks. When I started way back when the fleet was a mixture of Fords (mostly C cabs and Louisville 9000's) Dodges (yes they actually used to make medium and heavy duty trucks), Chevy and GMC 6500's and some Brigadiers (with 6-71's with mostly Allisons but also a couple 13 speeds).

At one point the majority of the medium duty trucks were GMC 6500 series 2 and 3 axle trucks with those 8.2 liter boat anchor "Fuel Pincher" turbo diesel engines and Allison automatics. The shop had a chassis dyno, and every week we had at least one truck a night on it checking power output before and after adjusting the rack because of low power complaints by the drivers. Of course all of the trucks were grossly overloaded. The single rear axle rigs that had digger derricks on them would get broken rear spring hangers and broken springs frequently. I got real good at replacing springs and hangers. And the engines were a joke. We would replace about 5 a year, the parts room kept several rebuilt spares on hand all the time.

Over time the fleet manager moved toward the International medium duty rigs with air brakes. They also had some class 8 trucks, International 9800 (one), Kenworth W900 (6) and a T660, and a Freightliner (with an ISX in front of an Allison).

Sometimes we would have some rental rigs with juice brakes, but they almost always had manual trannies and the parking brakes were drum brakes actuated by a pull typ e lever with a cable, mounted on the tailshaft of the trans. The occasional rig that had an Allison tranny but they still had the mechanical drum brake.

So by the time the GM started offering these PB setups, I was pretty much out of the loop.

 

[mechman]

Thanks for the resume.

 

[Racer X 69]

Thanks for the resume.

You looking for a technician?

 

[pop]

it looks like both of us are getting to old for this **** lol.

 

[Racer X 69]

it looks like both of us are getting to old for this **** lol.

I miss it a lot, but my broken body doesn't.

 

[pop]

you got right old man lol. dam that didnt feal good.

 

[pop]

dam beer it should say you got that right old man lol. dam that didnt feal good.