| Author | Message | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 155 Registered: 10-2007 Posted From: 206.45.93.160  Rating: N/A |
When I intially start my bus it builds to 90 lbs quite quickly, this is all good. But once It gets to 95lbs or so I get a air leak that seems to be coming from under my dash. It leaks quite badly until I hear a little pop sound like a valve closing or something, then it builds again as normal. Sometimes it takes quite sometime before it pops and starts to build pressure as normal. After it has gone through this proceedure it seems to work quite well. However when I shut down I do loose air until it hits the 90 lb mark quite quickly ,at that point the bus will sit at 85 to 90 lbs for a few days. Any idea where I should start looking? Wiper motor?? Grant | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 245 Registered: 12-2003 Posted From: 142.46.199.30  Rating: N/A |
It could be your windshield wiper motors or switches. | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 156 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
That's what I was kind of thinking , thanks | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 708 Registered: 7-2006 Posted From: 75.208.41.62 Rating: N/A |
Grant...I had similar problems with mine (under the dash)...turns out it was a defective quick disconnect valve; like the ones used on air tools. I replaced and no more problems....there...   RCB | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 157 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
Where was this valve specifically loacted? which side? I'm a little concerned as we are planning on using the bus more and more. I have a pancake compressor in case the system goes down, but with this darn leak the little compressor doesn't quite do it. | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 1 Registered: 5-2009 Posted From: 205.208.227.54 Rating: N/A |
Hi There, I have a similar problem with my 4106 except my leak seems to be underneath and I can't get any air pressure to build at all. My air horn was sticking and I got that quieted down but I keep hearing a loud hissing sound right about middle front when I start my bus. Any suggestions? Thanks, Kat | ||
| Craig Campbell (Craig_4104012)
Registered Member Username: Craig_4104012 Post Number: 42 Registered: 2-2009 Posted From: 72.59.17.12 Rating: N/A |
i had the same problem until i wiggled the wiper motor control knobs | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 2 Registered: 5-2009 Posted From: 205.208.227.54 Rating: N/A |
Hi Craig, You mean the control knobs on the dash? Thanks, Kat | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 712 Registered: 7-2006 Posted From: 75.208.41.62 Rating: N/A |
Grant...the dash...front of the wheel...where all the "stuff" is. But then, mine is a Crown and quite possibly much different than your coach. Start at the wipers, if they are air. Work your way thru the "system" that is up there(under the dash, which, if I recall is where you said you heard to leak)...one step, one thing at a time. Use a spray bottle with soapy water if you can't detect it audibly... Hope this helps. RCB | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 905 Registered: 11-2005 Posted From: 208.54.200.113  Rating: N/A |
For some reason this area seems to be a major source of leaks. Those Trico WW adjusting valves are impossible to repair or replace as far as I can find out. There may be more modern replacements available? I managed to repair one of mine but don't remember now how I did it. I do remember it was a pain and that it couldn't be repaired again. Seems to me there is a small piece of carbon that controls the amount and direction of the air flow but don't hold me to that. If they give more trouble I'm just going to replace them with plain air system valves even though I may not be able to keep the nice looking knobs I now have. I will most likely lose the "Park" feature also. | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 4 Registered: 5-2009 Posted From: 205.208.227.54 Rating: N/A |
My coach is a GMC 4106 and there are 3 knobs that actually work the wipers. They are part of the air system. I hear the leak underneath the frame in the middle front and am thinking my air adjustment valve may be stuck or have some dirt in it. With the bags down it's hard to crawl underneath to look. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 908 Registered: 11-2005 Posted From: 208.54.200.113 Rating: N/A |
Kat, What is the third knob? Sounds as if a PO may have added a third valve because the two WW valves leaked so much. I've thought about doing just that because I am tired of the leaking. I also found a bunch of leaks where the lines go into the valves, they are a peculiar type of fitting not common anymore. If they are tightened too much they will no longer seal and have to be replaced. I happened to have some spares, have no idea where they came from? | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 827 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Welcome Kat, No better thing than soapy water in a spray bottle to find leaks you can't hear, but. DON'T GO UNDER AN AIRED UP AIR RIDE BUS, OR BETWEEN THE TIRES AND THE WHEEL WELLS WITHOUT BLOCKING IT PROPERLY AT THE JACKING POINTS!!! We want you around for some more posts! George | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 6 Registered: 5-2009 Posted From: 205.208.227.54 Rating: N/A |
Hi Gus, Not sure what the third knob is. I think it's for wiper fluid as my rig has a wiper fluid set-up but it doesn't work. I will check all and see what I can find. I may have to get someone out here for roadside as I am out in the boonies. Thanks, Kat Hi George, I was actually thinking of digging a trench. I am pretty skinny so it wouldn't take much for me to shimmy underneath with a little trench dug out. I have my soapy spray bottle ready...lol. Thanks, Kat | ||
| Larry Nelson (Larryn4106)
Registered Member Username: Larryn4106 Post Number: 31 Registered: 8-2008 Posted From: 173.30.230.77 Rating: N/A |
That sound you describe reminds me EXACTLY of what happens about 1 hour to 90 minutes after shutting down in a campground, first the sound of air escaping, getting louder, louder, LOUDER....then my yellow brake knob popping OUT. Usually scares the dog. Whole event takes 8 seconds. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 909 Registered: 11-2005 Posted From: 208.54.200.119 Rating: N/A |
Larry, That is your spring parking brake popping off. It automatically comes on when pressure drops to around 50-60 psi. If you set it as soon as you park you will hear that same sound then. You should always set the spring brake when you stop. This is an emergency feature if you lose air pressure and don't notice it while driving. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 721 Registered: 7-2006 Posted From: 70.210.170.231 Rating: N/A |
Frankly...no criticisms here....I can't imagine NOT setting the brake upon a "QUIT" stop....FIRST thing I do...before I take my foot off the brake pedal. Just my way. BTDT...and wished I hadn't; began to roll as I opened the door! .... RCB | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 152 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
If that bus is loosing enough air pressure to pop the brakes in an hour and a half it has a few more problems than just the driver not using the parking brake. | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 234 Registered: 12-2000 Posted From: 24.164.20.23  Rating: N/A |
A leak down to 50-60# in an hour and a half is significant but not critical. I think it would still pass DOT inspection. As for the leak, you can use a 3-4 foot length of hose as a "stethoscope" to probe around under the dash and listen for the leak to narrow down the location. You could even do that with a longer hose taped to a broom stick to probe around under the bus or engine compartment without getting under yourself. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 153 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
I have decided to isolate some accessories that use air that are not necessary when camping run them through an air manifold and give them each an air toggle so I can shut them off, easily accessible from the drivers seat. For us there are 3 sources for leaking when parked that would cost plenty to completely stop leaking that is remedied by some 5 dollar air toggles. The engine compartment feed, ours has all the air belt tensioners that were standard with a bus with OTR A/C. The wipers. Finally we have 2 automatic ISRI seats and a dog that jumps in and out of it twice every 5 minutes. With these strains on air pressure are eliminated the only accessory air that is needed when camping is the air door lock and the step well slide and the auxiliary air compressor only needs to run maybe once a day to provide sufficient air. This is not a remedy for a bad part loosing lots of air but to eliminate slow air loss due to slight bubbling of of soapy water around components. The diaphragm for the regulator for the belt tension has a very slight leak that would not even be noticeable underway but with the engine off will drain the air over a week or so. Add the control valve the tension cylinders all the lines and you have all kinds of places to spend money to keep the air up when parked. Isolating these accessories like this will also aid in future searches for air leaks. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 154 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
A stethoscope certainly would not be necessary for a leak of that size. I would be embarrassed if I had an air system that was that poor holding pressure. Loosing 100psi in 1 hr????????????? You could HEAR the air escaping at that rate. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 727 Registered: 7-2006 Posted From: 75.210.28.5 Rating: N/A |
Last I was told (Border International, Las Cruces) was that DOT is 3 minutes...unbelievable, but said to be true. Point of applying the parking brake immediately is obvious...good practice makes for good habits makes for safer situations. Do it your way. Soapy aqua is still the best "finder"...MHO. RCB | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1604 Registered: 12-2000 Posted From: 76.66.18.100  Rating: N/A |
3 pound leak in 1 minute would be the expected performance standard to beat. Full air pressure, parking brake released, brake pedal to the floor, shut off the engine and watch the gauge hold steady. Is it a good thing or not that our conversions do not have to see the Federales for some periodic inspection? happy coaching! buswarrior | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 157 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
It is a good thing they do not. Look no further than their standard for air pressures, ridicules. I would never roll with a leak like that. No thank you we can do way better without. I was under the impression it was no greater than 10 lb in 10 min with brakes released, still ridiculous. I shoot for 0 loss, currently if the evenings stay above 50 degree the brake tanks drop to 80 and go down no further, the suspension holds indefinitely, winter and colder temps are a different story but winter is also a good time to look for them. Previous owners were corporate (regulated by the feds) bus air leaked worse than a screen door on a sub. Now it has a private owner and is much happier and no need for oversite by dewycheatumandhow. (Message edited by Joe Camper on May 18, 2009) | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 158 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
Buswarrior Our minister is a dispatcher at a large nationwide charter service, here in Chicago they go by central states charter. He drove for them for as long as he has dispatched he has worked there for years. Church picnics are great we talk buses. He told me there is not a bus in the fleet that holds any air pressure overnight. They have H-3's 40 or so, when the air bleeds off the air door bolt sets, all the drivers start them from the engine start every morn to get the doors open. I am sure they PASS all the bureaucratic bull. There is nothing they can do for us that we can not do better and cheaper. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1606 Registered: 12-2000 Posted From: 76.66.18.100 Rating: N/A |
That's a real shame. The new coaches are so easy to keep leak free, if the boss makes it a priority. The charter/linehaul company I spin the wheel with when I'm in the mood takes great pride in keeping the fleet leak free. Park it for the night at a hotel, just go out and start and drive away in the morning. No low air alarm, no sagging suspensions. If a coach is reported as leaking down, fixed that night on return. And every valve checked closely on inspections so drivers rarely get to report a leaking coach. I'm talking 200 plus coaches. Nice to have the founding old man still around many years into the international corporate world. happy coaching! buswarrior | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 732 Registered: 7-2006 Posted From: 75.210.201.236 Rating: N/A |
Not sure I completely understand the two posts Joe...seem somewhat contradictory to me...maybe just too late in the "day". "Ridiculous" , methinks is a fact of life in many "for profit" organizations...( AIG, et al). Seems to me what BW posted corroborates what you posted, somwehere in the above two posts....as what I was told at BI. Of course the prudent thing to do (as do I, but, alas, fall short) is to "shoot for 0 loss"...but then my labor is very cheap,,,my patience (don't ask my wife) very long, and my resolve very strong. I am pleased that one side remains at 120 for a very long time....and am learning to live with the other side going down more slowly than when I last "worked" on it; each time, I would add. Again, I apologize if I "mis-read". RCB | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1551 Registered: 12-2000 Posted From: 98.192.173.82  Rating: N/A |
The US DOT standard for bus air system psi loss is: Static: 2 psi/minute. Applied: 3 psi/minute. In a rare example of actually understanding, the US DOT obviously realizes that it's very difficult to maintain a totally leak-free air system. (The standards are slightly different for tractor-trailer rigs at 3 & 4 psi, respectively.) For the complete air brake check, it's posted in the Articles of Interest, and has been since 2001: http://www.busnut.com/bbs/messages/12262/16203.html?1167072614 FWIW & HTH. . . | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 159 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
RC what I meant to convey is all the bureaucracy in the world seems to to no good at all at central states charter. Warrier ponders gov oversite of bus conversions and I disagree. I'll bet there are a few reading this who would benefit from the soapy water treatment. Don't be scared jump right in the water is fine. It is easy and darn neer every time I snoop around with the soapy mix I can find a leak. While shopping for a bus and selling one, air pressure loss or lack there of is an indicator of the previous owners knowledge and perseverance in taking care of things. Very little makes me happier than to wake up to 100lbs on the gauges. Yes I am incurable. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 832 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Unfortunately, the Highway Patrol doesn't do a very good job of inspecting charter buses until something bad happens. As posted previously, my bus had a broken slack adjuster on the right drive axle, a missing yoke on the right tag, and a leaking oil seal on the left tag. The charter company's answer to poor braking was to set the governor up to 150 psi! This bus ran a gambler's tour from LA to Lost Wages 3 times a week over Cajon Pass, until they put it up for sale at a broker. It wouldn't build air over about a hundred psi idling, due to the leaks. Two weeks ago, a driver tipped a tour bus over on a freeway offramp returning from the coast. I believe ten people were killed, or injured, so two days later, the CHP did a surprise stop and inspection. 45 buses were checked, 3 were not allowed to continue, 17 more got repair tickets, and ten drivers were either not properly licensed, or medicals out of date... Then we buy them? G | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1553 Registered: 12-2000 Posted From: 98.192.173.82 Rating: N/A |
George - I guess it depends on where you are in CA. Around my neck of the woods, CHP's Motor Carrier Division inspects the bus fleets at least once every 13 months, often unannounced. It's also not uncommon for them to pull surprise inspections on the highways leading in/out of Yosemite & Kings Canyon National Parks. I've also been subjected to a surprise inspection in the parking lot at Disneyland during Grad Nite! But you're right - they're much more visible after somebody does something stupid. FWIW & HTH. . . | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 8 Registered: 5-2009 Posted From: 205.208.227.55 Rating: N/A |
Hi Debbie and Joe, I am going to do the soapy water treatment as soon as I can get under my rig. In the meantime, does anyone have any ideas as to what would cause no air pressure at all? I hear a very loud hissing sound coming from underneath the front of the coach toward the middle when I start her. Thanks, Kathryn | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1078 Registered: 12-2000 Posted From: 71.3.157.139  Rating: N/A |
No air pressure is because leak(s) is/are greater than the compressors capacity. Just a guess, but there is a leveling valve in the center front of the bus, right above the center of the front axle. Only way to know for sure is to get under there with a spray bottle. Be sure to BLOCK the bus before going under it. | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 9 Registered: 5-2009 Posted From: 205.208.227.55 Rating: N/A |
Hi Jack, That's what I think it might be. What size jacks do I need? Thanks, Kathryn | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 161 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
It sounds like an air tank or corresponding plumbing that is leaking if it is producing 0 pressure. You never know but if it is that loud it will not be hard to pin down. I do not know for sure on your old bus but usually you need to build 60lbs or so before the suspension even begins to inflate. You are new. Have you ever had a bus before, ever operated and maintained a vehicle with air brakes before. | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 10 Registered: 5-2009 Posted From: 205.208.227.55 Rating: N/A |
Hi Guys, I have had my bus for almost 3 years now and this is the first time I have had this trouble. The bags won't inflate at all. I get brakes but no pressure build up and yes, the hissing is very loud so it should be easy to pinpoint. Thanks, Kathryn | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1556 Registered: 12-2000 Posted From: 98.192.173.82 Rating: N/A |
Kathryn - Check your emailbox listed in your profile. RJ | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 248 Registered: 12-2003 Posted From: 61.10.5.98 Rating: N/A |
A stuck air dyer purge valve could be your problem. DaveD (Message edited by DaveD on May 21, 2009) | ||
| Kat Battersby (Ramblinruby)
Registered Member Username: Ramblinruby Post Number: 11 Registered: 5-2009 Posted From: 205.208.227.55 Rating: N/A |
Hi David, Thanks for the tip. Can you elaborate a bit more? Where is this valve located and what is its' function? I appreciate your input. Kathryn | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 162 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
I'm with Kathryn, could be a purge valve, verry simple to take apart and at least clean, could be some crap in it. I think my problem was between the WW switches and the park brake valve. I did take the valve apart and cleaned it. It was quite dirty and I also replaced the o-rings. It is better but not perfect. Think the valve might have some wear in it, and will just replace it. My air was going down to 90 lbs or so in the matter of a couple of minutes but now it takes an hour or so. I can still hear a little leaking back through the valve so I'll replace it. Thanks for the help guys. |