Air system question.......(I'm stumped)

Chaz · August 05, 2015, 12:43:48 PM

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

Geoff · August 05, 2015, 04:43:02 PM

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

Chaz · August 05, 2015, 05:02:17 PM

So, how can I flush it out?? Is there a product? Or does it have to "mechanically" cleaned out?
Thanx!

Chaz · August 05, 2015, 05:04:14 PM

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!

chessie4905 · August 05, 2015, 06:48:50 PM

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.

Chaz · August 05, 2015, 07:06:45 PM

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

yvan · August 06, 2015, 11:54:54 AM

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?

dickegler · August 06, 2015, 01:26:42 PM

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.

Lee Bradley · August 06, 2015, 01:30:51 PM

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?

Chaz · August 06, 2015, 06:14:28 PM

Nope, no air dryer.
Yeah, it's from 0 psi.
I'll check that out Lee.

Jim Eh. · August 06, 2015, 08:54:15 PM

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?

chessie4905 · August 07, 2015, 01:41:02 AM

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

bevans6 · August 07, 2015, 04:37:34 AM

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

TomC · August 08, 2015, 07:05:15 AM

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

Chaz · September 05, 2015, 12:53:11 PM

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.

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