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Topic: Sticking or bad air brake can? (Read 899 times) previous topic - next topic

Sticking or bad air brake can?

Someone just had this problem, but I can't find the thread. Today braking suddenly air pressure started dropping fast. Parking brake no issue. Get off the brakes and it builds back up. Does this require a Meritor specialist or just someone air brake knowledgeable?

I limped into a KOA after driving through Atlanta. Whew!
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Sticking or bad air brake can?

Reply #1 –
In my case is was a brake pod.

  • Engine at idle and air pressure builds up.

  • Put foot on brake and air pressure drops fast.

The Coach-Net mechanic that fixed mine said you can reverse a bad pod's function so you have service brakes but no parking brake.

If a bad pod is your problem and road mechanic will be very familiar with this. The only problem my mechanic is the pod on my 1999 40ft U320 are 30-24's, which he hadn't seen in 10 years. He thot current standard was 30-30's. So he had to make a parts run two times.


best, paul
Quote
Someone just had this problem, but I can't find the thread. Today braking suddenly air pressure started dropping fast. Parking brake no issue. Get off the brakes and it builds back up. Does this require a Meritor specialist or just someone air brake knowledgeable?
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: Sticking or bad air brake can?

Reply #2 –
Quote from: Dave Head –
Someone just had this problem, but I can't find the thread. Today braking suddenly air pressure started dropping fast. Parking brake no issue. Get off the brakes and it builds back up.

Looks like Paul beat me to it as I was typing.  Here's his thread on the subject

Lost Air in BOTH Tanks in Salem, OR

-M
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Sticking or bad air brake can?

Reply #3 –
Sounds like a pancake in the service brake pod, not the parking brake.  The pods are double, one part for service brake and other part is  for parking brake.  Would think any truck mechanic could solve that one real easy, most truck stops should stock those pancakes.
Dave

Re: Sticking or bad air brake can?

Reply #4 –
Woohoo! Chafed brake line! The guy from the truck stop ERS is on his way to put something together. I told him he would earn himself a forty buck cash tip...
I was having them come over to isolate that brake because they didn't have a 30-24 and I would have had to wait until Monday.
Now he's excited too.
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Sticking or bad air brake can?

Reply #5 –
Seems cash does talk.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Sticking or bad air brake can?

Reply #6 –
Hi Dave,
Maybe a leak in a brake air line? (Don't ask me how I know.) Do you or your spouse hear air leaking when the brake pedal is held down?

Jim
... Today braking suddenly air pressure started dropping fast. Parking brake no issue. Get off the brakes and it builds back up. Does this require a Meritor specialist or just someone air brake knowledgeable?

Dave Head & Starr Martin
Jim Frerichs
2002 U320 42'

Re: Sticking or bad air brake can?

Reply #7 –
It was a chafed line. I thought it was a bad diaphragm in the service canister since it had just happened to someone else.
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Sticking or bad air brake can?

Reply #8 –
Hi Dave, What is a "chafed air line"?

Re: Sticking or bad air brake can?

Reply #9 –
Quote from: Smitty71 –
Hi Dave, What is a "chafed air line"?

A brake line has rubbed through.  Could be on another line or any chassis component.  Easy to find, as there will be a massive air leak.

If the chafed air line is on the brake system, it will only leak when the service brakes are applied.  If a suspension air line, it will leak all the time.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Sticking or bad air brake can?

Reply #10 –
Raising the coach and blocking it, then crawling around under it with a light, you can find all sorts of interesting little things that might need attention, like a Ty-Rap to hold wires or hoses back from something, might see rusty area that needs some attention,  there are many areas that need a little attention once in a while.  Enjoy, I find it an adventure ;)

Re: Sticking or bad air brake can?

Reply #11 –
One that rubs on something and chafes until it wears through. Sorry if I miss-typed
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT