Community Forums

Jetboyblue · 04-19-2014, 05:43 PM

First let me start by saying "I'm new here" and hope I'm posting at the right place.

Here is my story...
I purcahed a 1994 American Dream from a private owner who had it for 3 years. On the subject of the pacbrake he said it never worked for him and he didn't really much care, (flatlander). I found the issue to be a plug missing in the air line input at the elbow going into the pacbrake itself. I put a threaded plug in and shazzam, it worked, but I don't think it operates quite right.
My issue, there is a foot switch and a lighted ON/OFF switch, and at idle setting still either switch will operate the Pacbrake as I notice a slight decrease in the engine RPM. When moving (flatland) at 70 MPH (6th gear)I can lift foot off pedal, step on foot switch and barely notice any Pacbrake assist. I get back up to 70 MPH set the cruise, step on foot switch cruise kicks off as it should, still barely any Pacbrake assist. I think this issue has to do with Pac brake not fully closing or if its closed its not sealing well. But lets move on as i think I have another issue...If I turn the ON/OFF switch ON it activates the Pacbrake, no matter what, at idle, or at 70MPH with foot on the gas pedal. I thought the idea was to put switch ON and drive, Pacbrake would only operate when foot came off gas pedal. Keep in mind cruise control kicks off when either switch in turned ON so that part is right. So is the barley (and I mean barley) any Pacbrake assist at 70 MPH flatland normal? And why would the Pacbrake operate when gas pedal is ingauged?

1994 Fleetwood Dream with Cummins 300 HP /Allison MD3060. Pacbrake install in 2007 according to records with MH. I would go to the shop that installed it but it's 2,000 miles away. Looking for clues here before going to any shop. Thank you in advance.

**TonyDi** · 04-19-2014, 06:01 PM

It sounds like you may a couple of issues here. For starters if you are at 70mph the effect of the engine brake will be slight. A severe retardation in speed would surely result in over-reving the engine. As your MH slows down does there seem to be any difference in how it responds at different speeds? You might also want to check the operation manual for the brake. I know my coach will not allow the engine brake and the cruise control to be on at the same time.

dennis45 · 04-19-2014, 06:05 PM

Quote:

Originally Posted by Jetboyblue

First let me start by saying "I'm new here" and hope I'm posting at the right place.

Here is my story...
I purcahed a 1994 American Dream from a private owner who had it for 3 years. On the subject of the pacbrake he said it never worked for him and he didn't really much care, (flatlander). I found the issue to be a plug missing in the air line input at the elbow going into the pacbrake itself. I put a threaded plug in and shazzam, it worked, but I don't think it operates quite right.
My issue, there is a foot switch and a lighted ON/OFF switch, and at idle setting still either switch will operate the Pacbrake as I notice a slight decrease in the engine RPM. When moving (flatland) at 70 MPH (6th gear)I can lift foot off pedal, step on foot switch and barely notice any Pacbrake assist. I get back up to 70 MPH set the cruise, step on foot switch cruise kicks off as it should, still barely any Pacbrake assist. I think this issue has to do with Pac brake not fully closing or if its closed its not sealing well. But lets move on as i think I have another issue...If I turn the ON/OFF switch ON it activates the Pacbrake, no matter what, at idle, or at 70MPH with foot on the gas pedal. I thought the idea was to put switch ON and drive, Pacbrake would only operate when foot came off gas pedal. Keep in mind cruise control kicks off when either switch in turned ON so that part is right. So is the barley (and I mean barley) any Pacbrake assist at 70 MPH flatland normal? And why would the Pacbrake operate when gas pedal is ingauged?

1994 Fleetwood Dream with Cummins 300 HP /Allison MD3060. Pacbrake install in 2007 according to records with MH. I would go to the shop that installed it but it's 2,000 miles away. Looking for clues here before going to any shop. Thank you in advance.

The Exhaust Brake does not function until you are below About 45-50 MPH.

BFlinn181 · 04-19-2014, 06:07 PM

Have you put eyes on the brake to be sure it is making full motion? If it had not been used or hooked up for years, a good chance the mechanism needs lube and exercise. Also suggest engaging below 70 mph, it's to help decelerate, not stop you.

Papa_Jim · 04-19-2014, 06:21 PM

Quote:

Originally Posted by Jetboyblue

... I found the issue to be a plug missing in the air line input at the elbow going into the pacbrake itself. I put a threaded plug in and shazzam, it worked, but I don't think it operates quite right.

The exhaust valve is not supposed to have a plug in there. I know, it looks like it should because there are threads there. Inside that valve is a valve mechanism that stops working. You need to replace the valve. It is very inexpensive. The figure $5.00 comes to mind, but I may be a little off.

It's a Humphrey SQE-2 Quick Exhaust Valve. You can order it from Cleaner's Supply. Their part # is PRT441 1-1.

Until you get your new exhaust valve, you can try this. I did this and used mine for a few years, and it seemed to work fine. Take that plug out that you put in there, and drill a very small (like 1/16") hole in it. Put the plug back in and see if it solves things.

Jim

hypoxia · 04-20-2014, 06:47 AM

Quote:

Originally Posted by dennis45

The Exhaust Brake does not function until you are below About 45-50 MPH.

Huh? Mine works fine at any speed, the higher the RPM the better it works. If it is the PRXB Pacbrake it will do the job at a lower RPM.
Operation of Pacbrake

palehorse89 · 04-20-2014, 06:56 AM

Some "REALLY BAD" information in this thread.........
My engine brake works at all speeds (everyone's should) , right down to 1st gear, 5 mph, then off, seems like more that one person has problems with their engine brake also here.......
At 70 mph, you should really feel the engine brake come on(and stay in 6th gear) as I would guess your engine is running at around 1900-1950 rpm's , or more.Here is a link http://kareninthewoods-kareninthewoo...pac-brake.html that has photo's and info. as mentioned above to rebuild it or troubleshoot it. Hope this helps you out.

Jetboyblue · 04-20-2014, 08:27 AM

1-When I step on the foot switch at 70MPH I held it there till MH speed was down to 35 MPH and I barely noticed the effect of the Pacbake at all.

2- I did put eyes on the Pacbrake but this was only in the driveway. As I mentioned as soon as I turn ON the ON/OFF switch the Pacbrake ingauges, so setting in the driveway I turned on the switch went back to the engine compartment and saw the cylinder extended.(This does not mean the cylinder actually fully moved the butterfly I will need to look closer to see if butterfly is slipping some how)

3- The Humphrey valve, when I first started looking at this Pacbrake issue I noticed when I turned ON the ON/OFF switch I would hear air leaking, switch OFF air stopped. So with switch ON I went back and put thumb over air link at valve and cylinder on Pacbrake started to move, put plug in and it appears to close fully. I assume that seal is bad on valve so I will get new Humphrey valve. (now $15.95 at Cleaners)

I did test drive another American Dream prior to buying this one and when I stepped on the pedal switch on that one doing 55-60 I could really notice the Pacbrake kick in and slow the MH down, again flatland.

Any suggestions on why the Pacbrake can come ON no mater what when switch is turned ON? Some safety funtion is not working or hooked up, I think.
Thanks Guys.

palehorse89 · 04-20-2014, 09:27 AM

Quote:

Originally Posted by Jetboyblue

1-When I step on the foot switch at 70MPH I held it there till MH speed was down to 35 MPH and I barely noticed the effect of the Pacbake at all.

2- I did put eyes on the Pacbrake but this was only in the driveway. As I mentioned as soon as I turn ON the ON/OFF switch the Pacbrake ingauges, so setting in the driveway I turned on the switch went back to the engine compartment and saw the cylinder extended.(This does not mean the cylinder actually fully moved the butterfly I will need to look closer to see if butterfly is slipping some how)

3- The Humphrey valve, when I first started looking at this Pacbrake issue I noticed when I turned ON the ON/OFF switch I would hear air leaking, switch OFF air stopped. So with switch ON I went back and put thumb over air link at valve and cylinder on Pacbrake started to move, put plug in and it appears to close fully. I assume that seal is bad on valve so I will get new Humphrey valve. (now $15.95 at Cleaners)

I did test drive another American Dream prior to buying this one and when I stepped on the pedal switch on that one doing 55-60 I could really notice the Pacbrake kick in and slow the MH down, again flatland.

Any suggestions on why the Pacbrake can come ON no mater what when switch is turned ON? Some safety funtion is not working or hooked up, I think.
Thanks Guys.

Someone wired it up wrong if I had to guess, The ECM-TCM should not allow the pac brake to move unless the Coach is at 5 mph, or above......same while downshifting, "All engine brakes" will shut down at 5 mph or in the case of a semi, rpm through the ECM governs when it shuts off, or else the engine would stall. I would think you should not be able to activate it while just sitting still, there are a lot of folks that use and have the brake switch on their Coach's, maybe one of them will chime in and be able to tell if if there is something wrong and where to look.
To lube mine and exercise it after lubing it, I take the air line off it and apply just enough air to the fitting on the cylinder to make it move, not a tight seal on the air nozzle, and press and let off the air nozzle and this moves the butterfly valve.
Brakeswitch, A better way to MANAGE your exhaust brake

6 wire?

Jetboyblue · 04-20-2014, 02:18 PM

The switch is just a standard toggle ON/OFF switch that is an extension of the foot switch. By turning switch on it's like holding foot switch down. Pacbrake should only come on when foot comes off the gas pedal.

wolfer · 04-20-2014, 08:22 PM

First of all since your pac brake has probably not worked in several years first you have a compressor probably mounted under the bed close to a rear corner or side of the engine compartment. Trace it back from the exhaust brake. First the exhaust brake has a butterfly valve inside the pipe behind the turbo it is controled by a cylinder that is air operated. There is a hose going from the compressor to the cylinder follow it back to the compressor. There are two wires a positive and a negative giving power to the compressor. The power wires go to a solenoid similar to an old ford starter solenoid with two big lugs one on each side and two smaller ones. hook up two ends of a jumper wire from the big lug on the left side and contact one of the small lugs and see if it operates the compressor. Your ignition key has to be on. If the cylinder opens and closes the butterfly valve it is not froze. That is half the battle if it does then it is an electrical problem. If your exhaust brake is on and you give it throttle it will close and your engine will overheat quickly and lose power.

Jetboyblue · 04-25-2014, 05:28 PM

I took the MH to local Cummins Care for service and asked their opinon on the Pacbrake...
The Humphrey valve is not working correctly and the inline assembly (the actual brake spring butterfly valve) needs replaced. I asked if it could be taken off cleaned and lubed (rebuilt) and they told me according to Pacbrake NO.

I'm thinking that with this model Pacbrake being 15 years old and the new style PXRB out there is no supporting parts or they are pushing the new PXRB.
Cummins Care wanted $800 for new Pacbrake and 2 hr labor to change it. I found a new PXRB model C40115 on line for $630 and free shipping. I'm thinking of changing the Humphrey valve ($15) and pulling and cleaning the existing one myself. If that does not work I'll buy the $630 one and change myself then if there is still issues let Cummins Care take it from there.