Engine/Transmission (1998.5 - 2002) Intermittant Pac Brake?

[Diesel Gunner]

Exhaust Brake is intermittant. All Electrical connections are good. Recalibrated the APPS at pin #23. Brake actuator does not move all the way to closed and at times sticks closed. It is well lubricated with Pac Brake lube and moves freely by hand with engine off and with engine running. Soleniod has been disassembled and cleaned with electrical contact cleaner and all vacuum hoses are in good condition with no obvious leaks. There does not seem to be any consistancy with the operation of this unit.



Might any of you have any suggestions of what I might need to do in addition to the above? I really miss having the brake. I use it every time that I drive the truck weather I am towing or empty. Have 91K on original brake linings with just under 1/2" pad remaing at last inspection.



Merry Christmas and Happy New Year to everyone.

 

[MasterLow]

Didn't see if you're auto or manual. I have one sitting in a box here and it has a switch that mounts behind the go pedal, might be worth checking that if you have one?

 

[cerberusiam]

Didn't see if you're auto or manual.

Look at his signature, 2001. 5 QC ETH/DEE. DEE is the designation for HD 6 speed manual.

 

[Diesel Gunner]

Yes, it is a 6-speed. No switch under the go pedal. I do use a two speed switch on the shifter and it checks good. The thing that is really confusing is that the actuator works smoothly without any binding, but works intermittantly and at times only partially. I can easily move it with my hand (when it isn't too hot) into the closed or open position.

 

[Bill Stockard]

Call PacBrake. I had a similar problem years ago with a PacBrake on my previously owned Y2K 3500 dually with a NV5600. I had the same setup as you with the 2-speed type switch on the gear shift lever and the electronic control plugged into the ECM (no switch under the accelerator pedal). I called PacBrake and they suggested several things to check. I don't remember the specific repair, but what they told me to do fixed the problem.



Bill

 

[Diesel Gunner]

Yes, I called them about 2-3 years ago about the brake sticking and they told me that I needed to replace the whole unit to the tune of about $800 then. Then, Jelag came through and got me some of the lube for it and it has worked well since. Recently, it started sticking and sometimes not engaging completely so I started lubing the heck out of it and the problem has become worse. Now it will only operate about 2% of the time.



Is it possible for the vacuum pump to be getting weak? The brakes work fine as usual and the actuator moves freely. As I have said all else seems to be fine. I even calibrated the voltage from the APPS at Pin #23 and have it within . 002v. Or do I need to remove it and reseal the actuator due to internal leakage?

 

[ewcmr2]

Is it possible for the vacuum pump to be getting weak?

Weak vacuum pump is possible but it's more likely to have a vacuum leak. Is your HVAC/cruise control working normally? HVAC will revert to defog and CC will not engage without vacuum.

Pull the vacuum lines loose from the brake/control valve and check if engaging/disengaging the brake supplies vacuum to alternating hoses.

The only time my EB malfunctioned was when a small vacuum line under the hood came unplugged.

 

[Ram4Sam]

I would think that if the vac pump was the culprit, your hvac controls would be acting screwy.



Sam

 

[Diesel Gunner]

Thank You, guys. I will get into a more detailed vacuum system check as soon as I have some time. I have not noticed that HVAC controls being nutty, but I have not been paying any attention to them either.

 

[petersonj]

I have a 2002 w/ 6 speed and Pac Brake with 176,000 miles. I use the exhaust brake frequently and when symptoms occurred like yours, it was a vacuum related problem every time.



Some things to consider. If you can get a hand operated vacuum pump tool, then hook it up to the vacuum cylinder on the exhaust brake. Operate the vacuum pump several strokes. The valve on the the exhaust brake should open fully and remain open. If it does not, you have found your problem. You can do the same test by disabling all connections to the engine vacuum pump and hooking it directly to the exhaust brake vacuum cylinder.



The vacuum cylinder is not serviceable, but is replaceable for about $150. 00. I know because I have replaced mine. If the exhaust brake passes the vacuum test, then I would be looking for vacuum leaks and the operation of the solenoid valve. I have replaced all related hose clamps with steel spring clamps. I know everybody hates them, but they behave like a constant pressure clamp and they work.



I have approximately 35% of original brake pad left at 176,000 miles. Exhaust brakes are great!

 

[Diesel Gunner]

Thank you petersonj. I will give the entire vaccum system a thorough check out this weekend. So the ebrake should remain open with vacuum on it? Seems like it should fail in the open position with no vaccum?



Did Pacbrake supply the replacement cylinder? That is one of the reasons that I was hesitant to call them, because the last time I did the "know it all" that I got hooked up with told me that I needed to replace the entire unit for $800 bucks or so when all it needed was lubed.



Apreciate the help, all.

 

[petersonj]

You are correct - my mistake. The exhaust brake will default to the open position without applied vacuum. So, when you perform the vacuum test, you will be closing the valve against a spring. Also, there are two ports on the actuator cylinder - the port on the rod end will close the valve, but use both ports for internal leakage tests. After full vacuum is applied to either port, place your thumb over the other port to test for internal leakage.

I purchased the actuator cylinder from a company called Poulson Wilson in Portland Oregon. The part number is C11 898 (back in December of 2007).

Poulson Wilson Inc.
11077 North Vancouver Way,
Portland, OR 97217
(503) 283-0700

The Pac Brake is actually very reliable. The one I have on my truck operated 70,000 miles on a previously owned truck, so the total miles are now around 246,000. I believe the only reason the actuator cylinder seal failed was because I experimented with making the engine compartment quieter. In doing so I inadvertently restricted airflow around the turbocharger and exhaust brake area. I have since rectified that condition. The new cylinder has operated for 50,000 miles flawlessly.

Good luck with your project.

 

[Pacbrake]

Diesel Gunner, from your explanation I agree with petersonj, your vacuum cylinder is most likely the issue. If you don't have a vacuum pump to test the cylinder it can be checked by removing the two vacuum lines to the cylinder. Then hold your thumb over the end of the vacuum line or fitting at the cylinder (depends where you find it easier to remove them) to create a seal. Then pull and push the clevis (attached to the butterfly shaft arm) in and out, you should feel a vacuum seal on your thumb, then switch ports (or lines) to test the other side. If you don't feel vacuum on your thumb then you found the issue. You could also remove the clevis pin and rotate the butterfly shaft to see if it is sticking within the shaft to bore.

Feel free to call 800-663-0096 with your findings or if you have questions or concerns.

 

[Diesel Gunner]

Checked out the sytem this afternoon and it is definately the actuator cylinder. Vacuum applied in either direction leaks through the cylinder easily. I am supprised that it was even intermittant.



I use this brake each and everytime that the truck is driven, weather it is loaded or empty or towing so this cylinder has many thousands of cycles on it. There is obvious play in the actuator shaft at the bushing in the housing and the play in the piston and cylinder can be felt from there also. I will contactact Poulson Wilson as petersonj recommended and since Pacbrake posted with some advice I will give them a call also to see if I can get the part.



Thank you all for your help and have a great new year.

 

[petersonj]

Glad to hear you found the problem. Since you are an avid exhaust brake user, I have an idea that you may want to consider - remounting your exhaust brake control switch to the floor area just to the left of where you place your left foot.

The benefit is that your left foot is already resting there and you need only to pivot your foot slightly to the left and let it rest on the switch. (The new switch will be a universal horn button). This momentary switch will stay activated for as long as your foot remains on it. You don't have to push on it - just the weight of your foot will keep it activated. It is effortless to use and requires no reaching. Also, the exhaust brake cannot be accidently engaged while shifting gears since the clutch pedal will have the attention of your foot.

I re-wired mine this way several years ago and I will never go back. I used a universal horn switch because I could find one that had a large button area that depressed with the lightest touch and the fixture had a low profile. I have it pinned to the factory removable floor mat with two carpet tacks, that way it is easy to remove for cleaning the mat and yet remains secure while in use.

I wired the exhaust brake switch in series with a three position power switch (on, normal, and off), so the power can be turned off if someone else drives my truck (such as my wife).

Anyway, I thought I would pass along the information, just in case.

 

[Diesel Gunner]

Installed the new actuator this past weekend and it's like ten years ago. Petersonj thanks for the suggestion, but I am so used to the switch on the shifter now that I am going to stay with it. (Maybe on the new truck?)



Thanks to all for your help, and I want to say thank you to Pacbrake. The last time that I had a problem with the exhaust brake and called you a young man told me that I needed to replace the entire unit for $800 when all I relally needed was a $10 bottle of lube. That worked for 2-3 years until the unit was actually worn out. The only question that I have left now is should the unit be lubed internally (actuator and valve) or do I only need to lubricate externally?



Thanks to all again!