-
Bummer in Branson
Pam & I just arrived in Branson Missouri. We should be all smiles as we are finally west of the Mississippi River but we are bummed. When we were getting the bus settled at the camp ground I discovered a air leak (noise) from the area inside of the drivers duals..
The culprit is suspected to be one of my new airbags. All my bags were replaced this summer. We leveled the bus and I have the air leak still doing its thing. I call Branson Motorcoach and they can’t see us until Tuesday morning. I’ll check pressure each day until then. I’ll run the air compressor to help keep my pressures up on Tuesday. Thank fully it’s only 4 miles to the repair shop. Really bummed this happened as the idea of replacing all the old bags and fittings was to avoid shineola like this.
Could be worse, I could have had this happen in a more remote area.
-
17 Replies
-
The height control valve is located behind the fender liner in front of the dual wheels on each side. Based on where you hear the air leak, this might be the culprit.
-
There are a lot of potential leaks in the area described and usually there will be clues about where specifically the leak origin is.
If it is an air bag leak the coach should settle down on that location. If the coach does not anything related to the air bags, including fittings and valves can be ruled out. The leak could be a relay valve on the braking system leaking. The dash gauges will reflect that.
If the coach is parked and the key is off it is highly unlikely the leak has anything to do with brake chambers or ride height valves because they do not have pressure on them when parked unless something is wrong elsewhere.
Not completely sure why it would be necessary to run the air compressor when parked.
-
I live 35miles north of Branson if you need any help or assistance I will be happy to help.
Roy
-
Hey Chip,
Hope You have a good water separator setup on Your Aux compressor. They tend to make quite a bit of moisture. Maybe the repairs will not be too painful.
-
I think John is correct on this. IE: relay valve for the brakes. My primary & secondary brake gauges fell to 40psi. The ride height is steady, even with the cold weather.
We shall nurse her to the shop on Tuesday. I’ll let you know what the verdict is.
-
Chip,
It is not uncommon for a brake system that holds air pressure forever to have a time when the pressure goes away in a few hours. Sometimes the relay valve does not seat properly, and it leaks.
However, if a leak occurs because the valve is old and failing and the pressure loss is normal it will not hurt to verify the valve as a culprit and get it replaced. They are both cheap and quick to replace and the consequences of trying to nurse one beyond its useful life could be you might experience a situation where you cannot build air pressure. Then it gets expensive.
-
Jon
i agree, with both primary & secondary pressure drops it looks like the brake relay valves. I will call on Monday and see if the have the replacement relay valves on hand. If they do, the valves will be replaced even if they are not the culprits.
-
Try not to shoot in the dark. A lot of owners call for service and get a lot of things replaced or repaired because they think those are the problem when in fact they are not.
A relay valve issue can usually be easily diagnosed. If you can air up the coach and the brake pressures drop after shutting the coach down the leak is almost always a relay valve. A fast leak can be heard. If both drop the problem is usually associated with the relay valve for the parking brakes. If just one system drops it is usually the relay associated with primary or secondary circuit.
If the coach will not build air pressure it also could be an air dryer purge valve issue. If pressure drops when the parking brake is released it could be the diaphragm on a parking brake chamber.
My point is before deciding what you are going to have repaired let the professional mechanics do the diagnosis.
-
Jon
the verdict from Branson Motorcoach is that the relay valve is bad. They checked her out today. No replacements in stock so they ordered the valve(s) from Prevost. Since the drivers relay is bad, i am also having the passenger side replaced. With Turkey day approaching rapidly, we are going to have the work done on Monday. This takes all the stress out on our side and theirs as they can release their shop crew early on Wednesday to be with their families. Pam & I are secure at the campground and will go enjoy time with our family as well.
Happy Thanksgiving to all the PC folks. I will post a final on this case next week
-
Glad they could isolate the problem and that you are safe.
Have a Happy Thanksgiving.
-
I carry a couple of relay valve repair kits. They are only about $25. By changing the internals vs replacing the entire valve, you do not have to move and re-orient all the fittings and you don’t have to wait for parts.
https://www.finditparts.com/products/370147/haldex-rn10hk
Gerald
-
Here’s a thread on the subject
https://prevostcommunity.com/forum/threaddetails.asp?Category=&ThreadID=6143
-
I will order the kits but there is one huge question:
What are people using supporting the weight while replacing valves? I’m not talking at a shop, I mean while on the road. I was warned that I should never go under a bus without proper support.
What do you use to prevent getting squashed
-
While I carry a 20 ton jack, I’d be hesitant to go under the bus on the side of the road. Having the kit just avoids waiting for parts. Any truck or bus place should be able to repair the valve with the kit.
Gerald
-
Chip,
Rule number one is to never ever go beneath the bus unless it is supported at the chassis support points. The Prevost web site has the specific location of those for your vintage coach and you should look them up and if you need to spray them with some really loud color paint so you always know where they are.
The chassis support does not have to be sophisticated but it does have to be strong, along with the ground beneath the supports. Hardwood blocks are just as effective as stands. If you use a hydraulic jack do not use the hydraulic section, but instead screw out the center screw so the support is all mechanical and is not relying on a hydraulic support that can fail.
Specifically the coach is unaffected by any pneumatic system repair work except for the suspension. A relay valve can be removed and replaced and except for air escaping from its respective air tank the balance of a Prevost pneumatic system that is working right will retain air.
Almost 100% of what you might need to work on beneath the coach is going to be in the steer or drive/tag wheel areas and once you get into those areas you can sit up and do most work. Raising and supporting the coach just makes it safe and easy to get under the coach to access what you need.
Log in to reply.