For starters, it probably takes about 20 mins. to air up. Yeah, that bad. Once I have enough air to manually high idle it, it comes up pretty quick...sorta (at least in my estimation.).
History:
I had this issue with an old compressor so I swapped it out. Still had the same issue so I bought a rebuilt. Same issue. Could the line be clogged that bad some where to cause that? The system could use a good cleaning for sure. Should I put some airline anti freeze in it to try to clean it out??
The only air leak I can find (since I now have ramps :) ) is the Valve (??) under the brake pedal in the compartment under the drivers seat. There is a SMALL leak out of the bottom of it where the air is expelled when you let off the brakes. I'd like to seal that back up but since I want to use the bus this weekend, I'm thinking I better not mess with it in case I mess something up and can't get a part for it. What do you think?
So, what can I try?? I'm struggling.
Thanx gents!!
Chaz
Yes, the air line between the compressor and the air dryer or wet tank can accumulate a lot of oil residue and cut the air flow quite a bit. The old air compressors passing oil into the air system would cause this.
--Geoff
So, how can I flush it out?? Is there a product? Or does it have to "mechanically" cleaned out?
Thanx!
Also, what is the "ticking" (fast paced) that I hear at the (I believe) "wet tank" in the old air conditioner bay? It sounds like it is coming from the back somewhere?
Thanx again!
Once it is aired up, how long does it hold pressure with engine off? It probably leaks off rather quickly. Connect an aux. Air supply to it so you can listen for leaks with engine off.
Chessie,
I did that. The only leak I found was under the brake pedal. The "green" arrow on the gauge leaks down rather quick. You can watch it move slowly. I would think the compressor could out pace that leak.
Thanx,
Chaz
Your best not to take a risk. Yes the compressor can outpace the leak in a static bus(I know existential question, is a bus eve really static...? ) but can it out pace a few quick jabs on the break treadle from the idiot in the car that cuts you off and breaks in your face?
Chaz,
do you have an air dryer?
If so, it can become clogged with oil from a worn out compressor. It would require a new desiccant cartridge.
When you say it takes 20 minutes to air up, is that from 0 psi? Once the system is up to shut off pressure and you fan the brakes to drop the pressure to cut-in pressure, how long does it take to come back up to shut off pressure?
Nope, no air dryer.
Yeah, it's from 0 psi.
I'll check that out Lee.
I see by your fotobkt pics there is no intake filter? Also the coolant return line seems out of place. There should be a line on either side of the cylinder head from what I can remember or does it exit out the back side of the head?
Leaking out of the bottom of the foot operated brake application valve could be from one of the dd3 rear brake chamber diaphragms perforated and leaking back through the lines. Try pinching off the three hoses to each rear chamber one at a time to see if leak stops.
Please locate and purchase shop manuals for this coach as they contain invaluable troubleshooting information on the brake system plus servicing and troubleshooting info on all systems on coach. Someone on here may have copes or Ebay or other sites. Coach information network is another such site
Compressor recover test is with the bus running and air pressure stabilized (suspension full, etc) fan the brakes to reduce pressure to 80 psi. Observe the governor change and the compressor start to deliver air. With engine on high idle or 1,000 rpm, time the rise from 85 psi to 100 psi, should be less than 45 seconds (in some regions the rule is 2 minutes but I think 45 seconds is long enough). Mine does that in 12 to 15 seconds. That is part of the DOT daily inspection. Pressure loss is with the air pressure above 100 psi, engine off, observe the pressure with brakes off, pressure drop must be no more than 2 psi in one minute. Next apply the brakes fully, same test, no more than 2 psi in one minute. Again this is a DOT test, if the vehicle fails it's technically not legal to drive.
Rear DD-3 leaking produces a leak at the exhaust valve at the relay valve, not the foot valve, as a rule.
Brian
My bus takes at least 20 minutes to air up if all, including the air suspension needs to be aired up. The air system should hold air pressure. Mine goes down to 60psi overnight. Once your air is pumped up, how fast does the air compressor recover? Good Luck, TomC
I'm still wrestling with this issue guys. Here are some pix of the actual compressor. Krank brought up an interesting point - and I don't know what to make of it.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi58.photobucket.com%2Falbums%2Fg279%2FSkulptor%2FDSC00608_zpsigmqw7ju.jpg&hash=6b90333695b8d160d3809eb32ac5fbd69cee87ce)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi58.photobucket.com%2Falbums%2Fg279%2FSkulptor%2FDSC00607_zpslf4uslmf.jpg&hash=291fb420055e407f73446805e9192afa1e667af5)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi58.photobucket.com%2Falbums%2Fg279%2FSkulptor%2FDSC00609_zpskdjecgwi.jpg&hash=645cdc3dfc57d1642401004fe76e807f07a7e42d)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi58.photobucket.com%2Falbums%2Fg279%2FSkulptor%2FDSC00610_zpsucv3weqi.jpg&hash=97fa87962c4d9320d8cbe3e4f3ffdd9828f05078)
Maybe seeing the actual compressor will help - I certainly need it!! ???
I have the manual with the bus but find it MUCH more less time consuming - and enlightening - if I can bother one of you for some help.
I want to clean the system anyway so, what would you suggest??
Thanx again!
Chaz
Everything is there in way of plumbing,it probably doesn't have filter looks like the intake hose is headed for the blower which is a common place for the compressor intake on the older buses
Cool. I was hoping it was correct. It's how I got it. And it does go above the blower for air.
So how could I clean the system? I'm hoping a good cleaning will help with air up time. I don't know what else could be wrong????
IMO you just have a ton of small leaks most of the time when the tanks are full of curd they air up faster less volume to fill
But I "think" the lines may be plugged. I did have to "rod out" a valve (to atmosphere) with a wire to open it up. So I am wondering if that could be an issue.
There also seems to bee a....for lack of a better word.....wispy leak that has a rhythm to it. Hard to explain but - psst...psst...psst...psst...etc. when the motor is running. It is about 1 second intervals or quicker. I just can't find it to tell what it is. I guess it could also be exhaust or something else????
Man, I'm just frustrated with this............
Thanx Luvr.
if the air lines are plugged then the regulator would keep exhausting, ie unloading the compressor. i have an old mc5 that unloads into the intake so you dont hear it blow off. only can tell when the sound of the motor changes.
I love the sound of blow off! Sets the bus apart from all the coal roller pickup trucks out there. Can someone answer his question about what to use and where to insert cleaner for the lines? I'm curious tok
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I never heard of injecting a cleaning agent into a Bendix system, the main supply line will coke up and you just change it.
Bendix tells you it will take a while with draining the the tanks to clean the system after a compressor failure adding a cleaning agent they make no mention of it
You can probably buy some type snake oil that will tell you how great and easy it is,I wouldn't attempt it to many sensitive valves,o-rings,diaphragms and seals to chance it IMO
I know when you do get oil in the air system it's usually black and thick like gear lube. Any way the oil accumulates at the bottom of every thing and will come out when you drain the water out. May be a separator on the right wall of the engine compartment. Should have a drain on it be careful because the goo will come shooting out of it. And the oil come out best under pressure because it's so thick.
IF you wanted to go through the effort you could use methyl hydrate to flush the lines (disconnect both ends). If any valves need cleaning best to remove, disassemble, clean and reassemble with a rebuild kit.
Quote from: krank on September 06, 2015, 07:48:00 AM
IF you wanted to go through the effort you could use methyl hydrate to flush the lines (disconnect both ends). If any valves need cleaning best to remove, disassemble, clean and reassemble with a rebuild kit.
I have and have seen 100's of rigs in the Arctic that had HEET poured and pumped thru the air systems. none suffered any damage.
Mostly to facilitate freezing, but it does move sludge, to a point. it may not cure..but it won't hurt.
i would definitely inspect the main discharge line.
The oil is only suspended while the air is compressed as the system cools off the oil condenses and reliquifies. The heat from compressing the air turns the oil into a vapor that can be explosive, but would need an ignition source. Adding any flammable solvent would oh lower the flash point of the gases in the system. Best is just disconnect the lines and blow them out as best as possible. The tanks are not bothered by the oil. Just keep draining them. Once in the bottom of the tank. The oil stays liquid. But may cause the bottom of the tanks to rust more if you leave the water in them. In a fuel system the low oxygen levels keep the electric fuel pump from ignighting the vapor. in compressed air system the oxygen level could produce the right level of carburetion. And you shouldn't be adding any vapor if you replaced the compressor with a good reman.
When i first got this bus, there was a problem airing up according to the dash gauge. I decided to change the sensor. When I took off the old one there was a large amount of slop that began to ooze out. It seemed to me that the location of the sensor, below the driver in the spare tire compartment, put it at about the lowest and most distant point from the compressor. I think Luke had said that I could try running some alcohol through the system to clean it, but I never did. I just drained what I could and put the new sensor on. No problems since, but sometimes I think I should open it up and see if there is anything more there. I would guess that if one were to remove the sensor and start up the bus, it would blow a lot of crap out.
Quote from: jackhanow on September 06, 2015, 10:15:09 AM
The oil is only suspended while the air is compressed as the system cools off the oil condenses and reliquifies. The heat from compressing the air turns the oil into a vapor that can be explosive, but would need an ignition source. Adding any flammable solvent would oh lower the flash point of the gases in the system. Best is just disconnect the lines and blow them out as best as possible. The tanks are not bothered by the oil. Just keep draining them. Once in the bottom of the tank. The oil stays liquid. But may cause the bottom of the tanks to rust more if you leave the water in them. In a fuel system the low oxygen levels keep the electric fuel pump from ignighting the vapor. in compressed air system the oxygen level could produce the right level of carburetion. And you shouldn't be adding any vapor if you replaced the compressor with a good reman.
seriously ?.... back before air dryers, every vehicle that encountered freezing and potential frozen condensate in an air system had an alcohol evap system... haven't heard of any railroad cars exploding....
The difference is the alcohol is misted in after the compressor not though the compressor and there is no ignition source besides the fact it's a really small amount of alcohol unless your trying to thaw the system because you didn't fill the jar soon enough. And every time you pump the brake the vapor passes to the outside. Simple science is compression makes
Heat and expansion cools.
Get a mechanics stethoscope and start hunting near compressor. Also drain all air tanks and leave drains open to allow accumulated oil and sludge to completely drain out, at least one or two days. Tank at rear bulkhead, in compartment under driver, and two above batteries on 4905. My 4905 has air drain pushbutton inside fuel filler door for the main air tanks. Make sure all drains actually work and aren't plugged up. The air system is designed to accumulate most of oil and moisture in wet tank; much less in others that receive their air from wet tank. An air supply to the system without engine running can be very helpful.
Get a mechanics stethoscope and start hunting near compressor. Also drain all air tanks and leave drains open to allow accumulated oil and sludge to completely drain out, at least one or two days. Tank at rear bulkhead, in compartment under driver, and one above batteries. There are 2 air drain pushbuttons inside fuel filler door for the main air tank. The tank is divided into two sections, wet and dry.Make sure all drains actually work and aren't plugged up.There is also a moisture drain on the compressor muffler, which is shsped like a fat horiz. Sausage by the compressor. The air system is designed to accumulate most of oil and moisture in wet tank; much less in others that receive their air from wet tank. An air supply to the system without engine running can be very helpful.You did also replace the governor when you did the compressor ? Small air leaks at idle can extend air build up significantly.
That air leak at the brake treadle.....does it leak with the dd3's applied or released?
I'll have to look.