Air system questions

Tedsoldbus · June 23, 2022, 10:47:04 AM

When I shut down I know to bleed my tanks and my little air bottles front and back. Within a couple of days, my two air gages go to zero. But the suspension takes about a week to drop a few inches and about three weeks to drop the frame as low as it goes. (I have been told to be happy about that)Are the brakes and suspension separate air systems? All filled from one compressor? Isolated with check valves so keeps them separate from both bleeding out in 3 days?? My bus is spray foamed underneath so hard to follow what is going on. (Also told I should be happy about that, but I can't see anything).
Rita does not like the bus flattened and bugs me to start it so it airs up. I found two large beams that just slide under the frame in front when I pull the bus into the shop. Now it does not settle more than 3 inches so she is happy. I don't start it just to air it which I think makes the bus happy. Any issue with letting it settle on blocks?
My tanks all bleed pretty clean but the front one always sprays some moisture. Three mechanics looked hard and say I do not have an air dryer. A diesel mechanic I met in Evansville recommended I find a way to get some Alcohol into the system or the water can hurt gaskets inside the air release valve. If a good idea, where would I introduce that??

TomC · June 23, 2022, 11:46:40 AM

Carry a California 2hp compressor (very quiet) to pre air before starting and to keep the air up at all times. Plumb it directly into your first tank from the compressor. And you should install a air/water separator-then you only have to check the air tanks once a month. Good Luck, TomC

luvrbus · June 23, 2022, 12:04:53 PM

Bendix stopped using alcohol in systems years ago,alcohol dries the seals and o-rings out in valves and regulators and makes for more leaks a $200.00 air dyer is the best way to go

Busted Knuckle · June 23, 2022, 12:07:07 PM

OK first off the brakes and the rest of the air system are on separate systems. Now the reason your suspension stays up so long, (and yes that is a good thing) is because once air goes in the air bags it stays because the leveling valves won't let it out unless it gets too high. That's good because it means that your air bags, leveling valves and associated tubing and connections are all in good shape!

Now you could do as Tom says and add an auxiliary compressor to keep things aired up, and for airing up on the sly at campgrounds. You could plumb it as Tom describes to air the whole system up, or you could just plumb it to keep the "accessory" side up. (with a valve to open and air up the main system if desired for stealth mode airing up for early AM departures.
I personally like them plumbed the aux system with the ability to air up the rest only as desired. That way the pump comes on much less, and it allows you let the bus air system do it's job while you do your pretrip inspection for normal departures. (that way you know it's working as it should, and no sudden surprises that it's not working when you REALLY need brakes!)

As for letting the bus settle on blocks there is nothing wrong with that either lots of busnuts have a block made up for each corner of the bus to let it rest on to make a firm stop for the bus to stop swaying and rocking.

BK

dtcerrato · June 23, 2022, 12:23:15 PM

Speaking from a vintage GM Coach platform the brake and suspension receive air from the same compressor. The suspension and misc. air for wipers, horns and such are fed from air that enters into the auxiliary air tank through a pressure protection valve that only starts filling that tank when pressure reaches around 60 psi - with that said the braking system fills or gets its air first then @ about 60 psi finds its way to the aux tank. Your suspension is staying up longer than air in the system probably because your suspension leveler check valves are working as they should. Our bus has always dropped in a few days. When not using it regularly or prolonged camping we block the body using the front & rear bulkheads or we have the option to run the aux on board electric air compressor to keep the suspension up. Im with Luvrbus on the air drier - after 35 years of ownership w/o one we asked ourselves wtf took us so long to upgrade to a drier?!. Foam is a great insulator but has it's limits when common sensing not to cover what may need future maintenence. Your getting your feet wet now with your bus...

richard5933 · June 23, 2022, 01:58:32 PM

What Dan said...

On my 4108 it did about the same when I first got it - the gauges would go to zero in a day or so and the air bags would hold the bus up for a few weeks and then slowly drop.

After the first spring I had gotten the air system tightened up so it would hold up for months, and by the first winter it stayed up till spring.

This took countless hours of my checking everything I could check, tightening ever air line fitting I could find inside every hatch, panel, cover, etc. Every time the bus went to the shop, there was a standing order for the mechanics to check every air fitting they could see. It took a few months but it was finally done and the bus would stay up on the air bags.

Eventually I had to replace the front air bags and all the height valves as they started to leak. The air bags leak out to the atmosphere and can be checked with soapy water, but the valves were leaking back to the tanks when the check valves failed. That was harder to find.

If your or your wife's OCD get to you, it's possible to get the bus to stay up on the air bags. Otherwise, the earlier suggestion of installing a small electric compressor in parallel with the bus's compressor will allow you to air up the bus without running the engine.

freds · June 23, 2022, 02:21:05 PM

Hi Tod

Your aux air input should be in the battery compartment next to the primary fuel filter.

Be careful it's probably full of water. I ended up taking off the quick disconnect connector to free it up and a bunch of water came out. Fire up the engine with it off to make sure it's blown out.

With the motor running you can run air tools off of this connection.

I also have an alcohol bottle in the same area on the bulkhead, so I guess I don't have an air dryer also.

Also there's a big air tank hidden up above the front wheels that I have never attempted to drain...

Tedsoldbus · June 23, 2022, 05:10:02 PM

Interesting pictures Fred,
I have no air input that we can find. I have no alcohol bottle and based on above advice I will dump that idea and figure out how to put in an air dryer. Both Prevost and both 1980, but you are 40 feet. My owners manual is for a 40 footer and not reliable on many things. No grease fitting map for the 35 footer that I can find for example. My aux air tank is under my seat. Has a jack to air a tire. All of my tanks have cables I can pull to release air. I'm not a mechanic but I'd recommend you get a release valve in that big tank. That is your air brakes or suspension or something that needs the gack out of that tank. I also have what two guys have called "yarn balls" One in front above the accessory tank and it says accessory tank drain. Don't know what the rear one drains, but PO did not know what they were and did not touch them. An old guy showed me there is a petcock on the bottom you twist sideways. First time they were tough to turn and had fluid in them. They got easier to turn over time and I drain them after every day of running like the big tanks. Nothing comes out them now but air or maybe a little mist once in a while. Like DTCerrato said. Us new guys are working our way into the guts of these things we love...
All of my tanks have cables I can pull. Some under the wheel well, and the cable looks shiny so somebody added them me thinketh...

Tedsoldbus · June 23, 2022, 05:17:21 PM

I am lucky in that the three POs each added something. A block heater, a battery charger for the engine batts mounted in the engine compartment, and a fuel prime switch there. I was afraid to try it, but tried that for the first time at last fuel filter change. Why wait until out on the highway with a needed filter change on no diesel to fill the filter to keep from losing prime? We filled the big Racor with diesel but left the little spin on empty. We threw the toggle and a little pump went z z z z z until it slowed down and stopped. Hit the start button and it fired up fine. Guessing I will know all the owner operator stuff about the time I get creaky and need to sell it!

Tedsoldbus · June 23, 2022, 05:21:23 PM

Hey Fred. How do you make your pictures big? Are mine smaller because of the size of my bus?
Crap. I guess size matters after all....

oltrunt · June 23, 2022, 06:32:38 PM

I put copies of my pics on postimages.org for free and then share them using the servers "direct link". After my experience with photofuc--er--photo bucket I don't trust the free services for storage of my pics but for posting who cares. All my pics post up like this:

. Jack

freds · June 23, 2022, 06:35:57 PM

Quote from: Tedsoldbus on June 23, 2022, 05:21:23 PM
Hey Fred. How do you make your pictures big? Are mine smaller because of the size of my bus?
Crap. I guess size matters after all....

Dang Ted we are going to have to meet LOL!!!

I didn't see the power steering hardware in your front compartment, so do you have arm strong steering and hey no floor pan in the same compartment?

As to the picture size I think you are doing file attachments which automatically shows a thumbnail until you click on it.

Since I co-own a small software company with da X we have a company website internet presence. I then use the IMG tag in my posts and refer to an actual image file/URL which is used when presenting the web page.

How about PM'ing me the serial number of your bus and I will do a bit of research. I find it interesting that you have the vertical lift bay doors and I have the rubber hinges at the top for the swing out doors.

Tedsoldbus · June 24, 2022, 04:41:41 AM

I have the same doors you do and 2 of the rubber hinges are getting a few small cracks. My front compartment swings to the side as does the back door on the passenger side of the bus. Nothing goes "up". Will PM serial number.

buswarrior · June 24, 2022, 08:08:47 AM

Big Transit here had lovely hardwood 4x4 blocks, the magic length to readily slide into the gap between the axle and the bump stops, ring in one end and a short leash of rope to drag 'em out when done.

Painted hi-vis yellow too.

Serve as wheel chocks too.

Happy coaching!
Buswarrior

Tedsoldbus · June 24, 2022, 08:34:06 AM

Thanks Buswarrior. I can see that under my bus and like that idea. Now to find wood!
Bus serial is M 502 261 79 and it left Prevost for Foretravel in May of 1979.
See Fred. I have the same doors. I know you like the idea of pull up doors, but these work. Just have to change the rubber hinge now and then. BCM guys sent me the stainless hinge idea and how to, but the rubber lasts a long time and matching the paint would be a trick (or $$$).
Now and then I watch Bus Grease Monkey just to learn what things are. Recent episode was a shorty Prevost a guy had recently purchased. It made me feel good about what great shape mine is in. The guy must have left a pile of Benjamins when he departed and Luke up in Vineland must have been happy....
Yikes..
But it was fun to see another 35 footer back on the road!