| Author | Message | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 6 Registered: 3-2010 Posted From: 67.174.144.159  Rating: N/A |
Need some Info Please.No hurry it is at home base. Maybe some of you have had this problem and know what it is. I came out this morning and have been working on inside of Our MCI mc5c (Saudi)we just purchased. The old owner said it holds air sometimes for a month and sometimes for a week.I had just loaded the big bay with all my tool boxes don't know if the weight change would matter? This was 3 days. He said he put a 3 inch spacer (which in my book is unacceptable?)between the bump stop on the left side rear to level when it sits down. Someone also cut out the right rear wheel-well to make it flat but never did the other side. I put that back in because in my guess it was there for a reason. So when I came out the bus was sitting sloped to the left rear. Looked under it and the airbag was empty. I started the 6v-71 with 740 Allison up and let it air up which brought it back to normal height which took 15 minutes. It took 10 minutes to 60 PSI then high ideal kick in and 5 to go the rest of the way. Shut the motor down and walked the coach listening for any leaks. At the left rear wheel-well area just in front of the tire there is a bump out in the wheel well as if there is a tank inside(maybe the dry tank?). I noticed a hissing or light buzzing sound that over an hour decreased to a low level and then stopped. Can't see anyway to get in there except a little door in the left back bay at the bottom about 5"X 5" which my 68lb LP tank is in front of but can move if needed. Sprayed Bags and connections with soap and water and saw no leaks. So what do you all think might be going on and how would you suggest I fix the problem. All help is much appreciated. Dave | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 971 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Dave, The air system in yours and mine has a protection valve which doesn't let air into the auxiliary tank until all the brake reservoirs are up to about 60 psi. This is why the fast idle is slow to engage, as it is an air powered auxiliary, as are the air bags. Obviously you have a leak somewhere in the rear, which you can find with a squirt bottle full of very soapy water. DO NOT GO UNDER YOUR BUS WITH THE AIR UP, OR BETWEEN THE TIRES AND THE WHEEL WELLS, without blocking it SECURELY at the jacking points! We want you alive and enjoying your bus. Okay, there are two leveling valves in the rear, one on each side, and one in the front which only maintains the front height. The rear valves control the rear height, AND the side to side leveling of the whole bus. When one side drops, the valve should open to add air to the bag, however, if there is no air, no raise. There is also a check valve which SHOULD prevent air from flowing back out of the bag into the aux res when the valve wants to raise, and the aux res is empty. Probably either your check valve is leaking internally, and/or your leveling valve or the left rear bag or tubing is leaking. Its squirt bottle time, there's just no better way. An electric compressor will make it easier and quieter, if you have one. Adding weight will certainly make a difference in the rate of decline, and as I described above, the leveling valve would have wanted to add air to keep the bus level when you added weight. Since the aux res had none to give with the engine off, and if you have an internally leaky check valve, the left side would settle as soon as the valve called for air. Welcome, George | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 8 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Thank You George for the great info. Yes I will not or ever get under it without it being blocked 1st. The only hissing I could hear was coming from the tank in front of the left-REAR wheel-well (which I can not get to but I will also check with soapy water tomorrow. It has stayed up all day today after I filled it up. When using a compressor ( yes I have 3 of them I am A general contractor and in California they are not in use right now? So I can use them. Where do I put a fitting to hook in the electric compressor. I have one back in the rear side bay that has a sign o it to drain it daily which I would suppose is the condensate from engine compressor.I also have three Maintenance manuals which show lot also. I have rebuilt regular motors and trannies but not these behemoths but will learn gradually. And does sound like a check valve. If it is, can I rebuild it or does anyone know where can get and how much they cost near Sacramento,California Dave | ||
| Tom Yaegle (Tom_5c)
Registered Member Username: Tom_5c Post Number: 43 Registered: 1-2008 Posted From: 71.169.124.171 Rating: N/A |
Dave, The 3 inch blocks will keep it from falling on you if a bag goes out. Check the drain on the rear brake tank, maybe your leak? Tom Y | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 9 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
As that is true, I think I will still block it, eh? Tom I will check that also. Question ; why would the brake drain be involved if it got to 120PSI and raised back and brake exhaust did its thing at 120 and held air all day. Yes something I heard behind the wheel-well that I can't get to on left rear. Is that the hidden brake tank? It does have a 1/4" looks like plastic line sticking out the bottom but no air was coming out there. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 252 Registered: 10-2006 Posted From: 99.23.157.14  Rating: N/A |
There is 3 ports on a ride height valve. Most are Haldex If it is a Haldex the center port is to the bags. It should have an in line screen. The top port is the exhaust and it is normal for air to exhaust there, alot if way over ride height but it SLOWLY GRADUALLY tappers off as it gets close to ride height. Could take up to 5 min or so to COMPLETLY drop and stop. The bottom port is the source of air from the bus this is where the in line check valve is. It is the same type air valve that is in the valve stems on the tires. Haldex Valve is 75 bucks or so the shrader valve comes in a fitting kit in with that valve. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 253 Registered: 10-2006 Posted From: 99.23.157.14 Rating: N/A |
On our Prevo when you turn the key off solonoids close and isolate the suspension air from the brake tank air and one will not affect the other under these conditions. | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 10 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Thank you for that information Joe and Debbie. I will check this out also. It is still OK this morning and it never effected the air brakes at least on the short trip down the dead end street we live on that I checked that out on. I still don't know what the hidden tank is, in front of the left rear wheel-well is. I can see a what looks like a bump-out in the metal wheel-well wall that suggests a tank is in there, and that is where the sound of air temporarily is coming from for an hour after the engine is stopped. The coach doesn't drop during that time. Sounds like a balloon being squeezed off an then the sound gets less as time goes on and then stops.If I go into left rear bay, I have a 68lb. LP tank within 4 inches of that compartment and can see a little door at bottom of that wall. That is the only way into that compartment. I am about ready to get the sawzall out. I put my ear to that area and can hear it. Dave | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 256 Registered: 10-2006 Posted From: 99.23.157.14 Rating: N/A |
NOOOOOOOOOOO put the sawzall away. No good Mr bus driver no good. The air loss you describe sounds just like what a good ride height valve SHOULD sound like as it lets the bus back down from ABOVE normal ride height. Unless you are purposly raising it past ride height before you are hearing the hiss, it should not make that noise. If it is loud enough to hear it is a reasonably easy one to find. Be careful and make sure you are supporting it correctly. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 257 Registered: 10-2006 Posted From: 99.23.157.14 Rating: N/A |
Hey you MCI guys, do those buses shut off the source of air to the suspension when you turn the key off like Prevost does? | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 11 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Joe, didn't mean to freak you out with the sawzall but we contractors resort to them and bigger hammers when needed. I gues because no one knows what is behind that hidden area that is making the noise I want to see for myself! I think it still goes back to George explanation or the check valve and aux tank having no air until the brakes are full. If it has nothing to draw off of then that bag will go flat. I put in my sliding tool boxes full of carpenter's tools and mechanics tools. Other than cabinets I had not added any weight to it since we got it. Thats a lot of weight. 7.5 foot long, 14 inches high and 50 inches wide.I made them up to slide all the way across and then when needed I will pull the whole thing out to put in our Truck that we will tow behind. So the bus was adjusting but the motor hence the compressor was off and the system tried to adjust but drained the left rear bag and down it went. Probably a slow leak somewhere and I will have to take a look to see where, or internal leak in check valve? Thanks for everybody's great advice. She is still up this morning as I am working on the inside and not leak sounds. But I will bet she will slowly over a couple of days start to droop at that left rear. | ||
| Tom Yaegle (Tom_5c)
Registered Member Username: Tom_5c Post Number: 44 Registered: 1-2008 Posted From: 71.169.124.171 Rating: N/A |
Dave, That tank is for the rear brakes. Close to the brakes. There is a valve in front of the rear axle between the tires opens from the brake pedal and air from this tank applies the brakes. Tom Y | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 973 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Dave, Yours will not have come from the factory with solenoids. Joe's looks like a factory conversion with a leveling system added, which has a bunch of solenoids. From the sound you describe, it may be the inversion valve, or the relay valve leaking. As you notice, the bus doesn't settle when the leak stops, which means the leak is in the brake system, not the suspension? G | ||
| David Guglielmetti (Daveg)
Registered Member Username: Daveg Post Number: 157 Registered: 2-2009 Posted From: 66.122.182.221  Rating: N/A |
A great source for air brake related parts in Sacto is Capitol Clutch and Brake in West Sac...maybe on Duluth. All the counter guys are very knowledgeable...stuff is not cheap, but you get the right stuff and good quality. | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 12 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Thanks Tom now that answers what it is behind the wall because in the manual it doesn't show it there it shows it further up. Yes I know where the valves are but after blocking the jacking points and spraying all the fittings and valves and bags no leaks and I work in it all day building cabinets getting in and out, pulling out my tools and tool boxes and pushing the weight back in when done for the day no change in height, so lets see if it drops over night. Dave George mine was a factory conversion but way back in about 1986- 89 guessing because of the Cabinets but don't know what they did mechanical wise. When I got it there was only the bed left in back.a small kitchen new refer and stove top no oven new inverter just sitting on the floor of the hall closet but hooked up(4 Trojan T-105 house batteries are dead but will replace when can afford) and a couch, a National air ride drivers seat and 2 new air ride Bostrums seats that are just sitting there not hooked up. Does have a new wood floor in hall and kitchen and full bath. 3-40 gallons tanks which I wold like to put in bigger ones sometime at least Fresh and Grey. So pretty raw. Motor runs strong, has Koler Generator. So don't know but don't see any solenoids within the air system, so probably the original setup eh. Also thanks David for the tip on Capitol Clutch. Also "Valley Power systems" does DD's and Allison and Spicers, etc. in West Sacramento over by the CHP Academy. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 258 Registered: 10-2006 Posted From: 99.23.132.46 Rating: N/A |
Prevo did not do factory conversions they put out motorhome shells that then went on to be converted by individual companies. Both the charter bus and motorhome shells from the factory have solonoids controling spool valves that feed the suspension. The difference was that the charter buses could only manually control the suspension by lowering the front (kneeling) and the motorhome chassis could raise or lower all 3 corners front left and right. Some converters piggybacked the factory level low to make it fully automatic. HWH is one system that many converters used. | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 13 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
It is still up this morning. I don't have that involved a system (went on line and looked at the HWH system). Mine does have 4 Firestone gauges in a panel with up and down buttons in the middle on the front dash. If I push the front 2 down, 1 at a time while motor is off air in released from that side but don't notice much of a change. If I push up while motor running it does rise slowly but takes a while. It seams to hold around 40-45 lbs. The rear gauges are not hooked up so the PO told me. all 4 have up and down buttons with an on off switch in the middle of the rear 2 and it does nothing when flipped. Will have to pull out to see if even has lines to the Rear and what the switch is hooked to. So in looking back at the original problem. The left rear dropped overnight and bag was collapsed. Only difference in anything that day was that I added the weight of my tool to the front main bay. Sprayed all connections after blocking jacking points and found no leaks. Tried adjusting inside front bags with Firestone system which didn't do to much. With motor on system recovery to full 120 lbs and brake exhaust aprox. 15 minutes. Air noise from brake tank as if extra air is bleed off last about 15 to 30 minutes and stops. Have to now check out inverter valves etc. when get time. Will watch to see how long it holds. And I do know when it decides to go down it will be that left side rear. OK well thanks guys for all the help and will keep you all informed as to what is happening. Dave | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1876 Registered: 10-2003 Posted From: 71.58.71.157  Rating: N/A |
Does that panel have labels for the selector switch? that say hiway and manual? Might also say "level it" on it? | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 14 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Nope it just has Up ,Down at each button , then on the glass of each pressure gauge it says in red letters that are very hard to read, but says Firestone, then lower on the glass it says Ride Right. And between the rear ones that are no longer hooked up there is a toggle switch with on and off. It is all in a Black plate about 6 X 7 inches. Today I was in and out of the coach doing more cabinets and moving sink, plumbing and noticed the front door had closed which I have noticed happens when it is loosing air slowly in the rear left side. Looked at the gauges for the front and they were still at 40lbs. Checked the bags in back and still had air but looking at the front and standing in the coach I could tell it had lost some air? I started the engine and blew them back up to full again It seems that when I am moving in and out of it that it starts loosing height or air in the left rear. Or adding or subtracting weight. I will keep checking for leaks. Dave | ||
| Patrick levenson (Zubzub)
Registered Member Username: Zubzub Post Number: 205 Registered: 5-2007 Posted From: 174.91.225.235  Rating: N/A |
Suggest you get the manual for the bus....best $ you can spend....Maybe someone here has a pdf of it. Since you have time why not read all the posts on the forum...lt will give you a better idea of bus systems. | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 270 Registered: 11-2003 Posted From: 75.214.69.10 Rating: N/A |
I have the Level It system on my 5A and i also have the right rear air bag go down. All new bags 2-3 years ago. I can't hear air leaking any where, (impaired hearing from the army doesn't help matters), the soap test is negative, and some times it will go down in 2-3 days, other times it takes several weeks to drop. I am to the point where i now suspect that the leak may be at the control knob itself. To be able to take it apart i am going to have to pull my seat out first. It's the little air leaks that are a pain to find and fix. :>) | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 15 Registered: 3-2010 Posted From: 67.174.144.159 Rating: N/A |
Patrick I have 3 manuals fr the bus and have read and followed each on this problem. Each one is the updated version but alas I find not the problem so will keep trying. We won't be going full time until August or September so Have some time. Just though some of you might have had the same problem and with all the wisdom here on the BNO boards I thought I would ask. Hey Ed Are you talking about the emergency brake pull up knob? I check that but nada. | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 271 Registered: 11-2003 Posted From: 75.213.242.242 Rating: N/A |
Nope, i am talking about the pull up/push down knob on the Level It panel that controls the right rear air bag. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1878 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
one way to isolate the bag,s to check it/them is to disconnect line to bag,s (after proper blocking) and rig up a schrader fitting for that or those bags. manually fill it or them with an air hose to about 70 lbs. check after a few days to see if they go down or pressure drops. If no loss, problem can be in other lines or leveling valve components or in lines to level it. Also check for leakage at manual/highway valve. Buy yourself a mechanic's stethoscope and remove metal end to use tubing on end. It works great and should be in every coach owner's tool box. |