Air Bags - MCI-DL3-45 Chapter 2

plyonsMC9 · March 21, 2021, 09:53:59 AM

Good morning bus folks!,

From an earlier post, we had a lot of problems getting the correct front air bags for our DL3-45 and finally resolved via Continental. But now the correct bags have arrived, and fit.

The bags are the two piece design, meaning they seal (bead?) up against the top retainers lip on the mounting plate vs. being crimped on to the plate, and then the weight of the bus on the bags as they are inflated seals them. Best I can explain it.

The seals aren't happening and the bags are leaking where it hits the plate. Mechanic tried several times - and we even ran an air hose in from the shop compressor to try to get them to seat but still no joy. We are leaving the bottom of the bag unsecured as per MCI instructions during the process.

Pictures below.

Has anyone had this issue and some hints which could help? I've got the manual but basically just says to install to top retainer first and be sure the top bead is secured in the retainer's lip.

Thank you!, Phil

plyonsMC9 · March 21, 2021, 05:41:45 PM

Good evening Bus Folk!

Thinking about seating the bags as best as we can, then driving the bus a very short distance ( couple hundred feet ) to see whether the bags catch and seat on the ridge with the 'jostling' as the bus moves.

Any thoughts, concerns? Doomed to fail, or wild success?

Thanks!, Phil

** UPDATE 3.22.2021 ** MCI sez NO to this approach. Risk is that the air bags could rip on the lip of the metal top plate while grabbing the plate due to the increased weight of the bus.

chessie4905 · March 22, 2021, 04:38:52 PM

I thought that design was superceded by a whole unit with plates attached.

plyonsMC9 · March 22, 2021, 04:45:25 PM

Interesting, had just been replacing like-for-like. Maybe newer setup fits? Will look into that further. Not a lot of success so far w/ this approach.

Thank you!, Phil

plyonsMC9 · March 22, 2021, 05:29:27 PM

So far bolt patterns for newer plates are not the same. [edited] Still checking......
Thanks again, Phil

chessie4905 · March 22, 2021, 06:51:45 PM

Earlier 4905's used a two three piece air bag with separate plates, like yours. Is was superceded by new style with plates vulcanized to the bellows.

plyonsMC9 · March 22, 2021, 08:54:39 PM

So much easier to have just the air bag / vulcanized like that.

Do you know whether there was any kind of 'trick' to getting them to seal properly ?

Thank you!! Phil

chessie4905 · March 23, 2021, 04:17:58 AM

There was something in the GMC service manual on procedure. They show installing plates in bellows, aligning arrows on bellows with arrow on plates, making sure upper and lower plates are indexed to each other in reference to mounting studs. Inflate airbag to seat plates. Then sit assembly in arbor press and inflate enough while operating press to allow bag to fold into itself properly. Personally, I would change to the newer design if at all practible. Quicker installation and less chance of air leaks between plates and bellows lips. Did you talk to Luke about this? Maybe he would be able to get the newer style.

RichardEntrekin · March 23, 2021, 07:31:33 AM

Truck tire places will have some heavy goop "Murphy grease" they use to bridge reluctant beads. That and hit it with a blast of air.

plyonsMC9 · March 23, 2021, 09:48:41 PM

Thanks very much for suggestions re: procedures and grease. We'll give it another shot Thursday and I'll hopefully have a positive update. And yes, we did indeed contact Luke.

With best regards, Phil

RichardEntrekin · March 24, 2021, 05:56:44 AM

You are gonna laugh, but there is a similar failure mode on Goodyear air bags used on the Ridewell suspension Newells that happens when the coach is raised to maximum height. That bead breaks loose from it's seal. Twice, about a quart of Slime into the leaking airbag has put the show back on the road.

plyonsMC9 · March 24, 2021, 08:35:49 PM

Quote from: RichardEntrekin on March 24, 2021, 05:56:44 AM
You are gonna laugh, but there is a similar failure mode on Goodyear air bags used on the Ridewell suspension Newells that happens when the coach is raised to maximum height. That bead breaks loose from it's seal. Twice, about a quart of Slime into the leaking airbag has put the show back on the road.

Definitely keeping that in mind Richard. Wouldn't hurt for me to carry a couple of cans of the Slime with us.
Thank you!, Phil

chessie4905 · March 25, 2021, 03:40:38 AM

Maybe maximum height setting needs adjusted if that's possible.

RichardEntrekin · March 28, 2021, 04:15:59 AM

Did you get them to inflate? and what worked?

Curious minds want to know.

plyonsMC9 · March 29, 2021, 11:58:23 PM

Thank you for the follow up!
Found a replacement one piece air bag, bolt pattern match, size match. Will post part #s soon. Install should be later this week.
We shall see.

Kind Regards, Phil