Normal air bag bleeding?

Branderson · December 06, 2018, 06:51:11 AM

Hello gang, I recently got all my air bags replaced on my MC-8. Prior to that, it usually took a few hours for the air bags to bleed out whenever I turned everything off. Now that I have new bags, I have noticed that the bags bleed out a lot faster. I still maintain air when driving so no issue, I'm just wondering if the new bags are adjustable or if things are now working like they should be.

Now when I turn everything off at a campground for example, I better not take too long in getting the blocks underneath b/c they will drop within an hour. Just trying to figure out what normal is and if I should take it back to get looked at or adjusted.

Lee Bradley · December 06, 2018, 07:03:04 AM

Does not sound right. Mine will stay up for weeks. Maybe some leaks from the air line connections or the bags haven't seated on their seals.

luvrbus · December 06, 2018, 07:39:44 AM

Where the bags plated or was it kept original with the MCI air beams ?

Oonrahnjay · December 06, 2018, 07:40:21 AM

Quote from: Lee Bradley on December 06, 2018, 07:03:04 AMDoes not sound right. Mine will stay up for weeks. Maybe some leaks from the air line connections or the bags haven't seated on their seals.

Yeah, in my experience, anytime you do any work on air lines and associated components, you need to be sure that you have everything perfectly tight and leak free -- then go back later and trace everything down to find the items that are leaking. I don't know if things "take a set" or loosen up, or if I just missed them the first time, but there seem to be more leaks a week after I worked on the air system than two hours after I did. The factor of the large-diameter seats on air suspension bags can be an issue, too.

Branderson · December 06, 2018, 07:55:28 AM

Quote from: luvrbus on December 06, 2018, 07:39:44 AM
Where the bags plated or was it kept original with the MCI air beams ?

They were plated. Something that the other replies are confusing me is that even before my air bags would air out once I turned everything off. I'm not sure if they have a different model or not but it's my understanding that they are suppose to air down especially the 74 MCIs.

luvrbus · December 06, 2018, 08:23:38 AM

Is the bus dropping on all 4 corners evenly or 1 corner then dropping on the others ?

Branderson · December 06, 2018, 08:27:01 AM

All is evenly. I've only gone camping once since replacing the airbags and I always put blocks underneath 2 in the front and 2 in the rear and it was the first time I was perfectly level. I don't know if that was mere coincidence or not. I'm maintaining air while driving too.

luvrbus · December 06, 2018, 09:17:01 AM

It is probably the check valve then at the auxiliary tank where the bags get the air supply from.my MCI 8 would hold air for weeks

Branderson · December 06, 2018, 10:07:40 AM

Quote from: luvrbus on December 06, 2018, 09:17:01 AM
It is probably the check valve then at the auxiliary tank where the bags get the air supply from.my MCI 8 would hold air for weeks

Is the check valve near the front fender? If not are there valves at the fender b/c I can hear air coming out near the passenger front tire.

bevans6 · December 06, 2018, 11:46:28 AM

My MC-5C will hold air in the suspension for at least a week, even with zero pressure in the system. Check valves in the leveling valves, I believe.

richard5933 · December 06, 2018, 11:47:42 AM

Not sure about the MCI, but in the GM aren't the check valves in the leveling valves?

I've got new leveling valves all around, and after fixing a few minor air leaks my bus will stay aired up for months when parked.

I know that there are differences between MCI and GM buses, but dropping down in an hour seems way to quick.

Branderson · December 06, 2018, 12:34:59 PM

I talked to my mechanic and he was going to have me order leveling valve for the drive axle left and right but when I told him that I heard air coming out near the front tire, he said to hold on. So I'm going to drive it over there Saturday for him to look at it.

luvrbus · December 06, 2018, 01:05:15 PM

On a MCI 8 it is going to depend on the unit number, MCI changed the air system on the 8 as often as people change socks mine had a check valve at the auxiliary tank that feed the air bags it went bad I could stand and watch the bus settle down on the stops in a few minutes

buswarrior · December 06, 2018, 01:17:18 PM

No MC8 is intended to settle when shut off.

Unscrupulous mechanics know they can empty a newbie's wallet, and leave him feeling very supported...

Others have no problem letting you pay for their own education on buses...

Why the hell would it be acceptable to pay someone to improve air integrity and get the coach back with worse air integrity?

Get your radar spinning, you paid for a job to be done that wasn't.

Take a grain of salt or not, I'm a cynical old fart, legitimately earned... seen and heard way too much of this abuse of newbie's who can't defend themselves.

Happy coaching!
Buswarrior

Dave5Cs · December 06, 2018, 08:05:00 PM

On your MC8 if you have an AD2 air dryer( long white or blue cylinder with a purge valve in the middle of the bottom plate. It will sometimes stick open or get something stuck part way and keep leaking air when compressor is not running it will leak down pretty fast through that valve or no pump up when needed.
At the top driver's side big pipe that comes out has a big nut also. Inside that nut is a check valve ball type that will let air through if it is not sealing. You also have a airbag filter between the 2 big tanks in the wheel well hanging down. Make sure the valve on that filter is closed (cross ways to the pipe it on) Do not open that filter because they are generally rusted at the 4 corner bolts and will break if you mess with them. Don't ask me and three other people I know, how we know that)

Also at each connection to your airbags from your supply side at the hose end there is a small filter in that nut and needs to be cleaned if you never have just take it out and clean or replace them (Napa)and make sure those ends all 4 in back and 4 in front are tight and not leaking air. HTH