2001 MCI 102DL3 - Driver's side lean on startup...

mqbus767 · November 16, 2018, 04:39:46 PM

Hello Bus Nuts,

Well, time to start the repair and maintenance on this new adventure.

When our bus is started and building air, it leans quite heavily to the driver's side. Even after air pressure is fully up, the bus does not automatically level out. If I raise and lower it a couple of times with the kneel switch, it seems to lean less, but it's still not quite level. Only after driving the coach for a few hundred yards does it seem to completely level out.

Other possible relevant information:
* It's behaved this way since we purchased the bus just about a month ago
* The "low air tag axle" tell tale does illuminate during this time period, but eventually goes out
* Air pressure seems to build quickly enough up to 110-120 PSI and holds
* During a cold morning this past week (40s), the air pressure built up only to around 90 until the bus was moved a few feet down the road and then it increased to the typical 120

Any ideas on where I should start my search?

Thanks!

lostagain · November 16, 2018, 06:38:00 PM

Leveling valve on the driver's side drive axle might be bad. Cheap and easy to replace.

40s is not cold. However, below freezing temperatures would bring on problems with the air system if there is moisture in it. Maybe time to service the air dryer then.

JC

richard5933 · November 16, 2018, 06:49:10 PM

Could the delay on pressure build-up on the 40-degree day be due to a sticking governor on the compressor? if so, they are cheap enough to replace.

luvrbus · November 16, 2018, 06:55:10 PM

It is your leveling valve on the front axle mine did that the MCI DL3 uses 4 leveling valves 2 at the rear axle and 2 on the front axle it doesn't have the standard 3 point leveling system like older buses,pay the price and buy it from MCI or it will drive you nuts with a aftermarket brand BTDT

thomasinnv · November 17, 2018, 07:22:44 AM

Quote from: luvrbus on November 16, 2018, 06:55:10 PM
It is your leveling valve on the front axle mine did that the MCI DL3 uses 4 leveling valves 2 at the rear axle and 2 on the front axle it doesn't have the standard 3 point leveling system like older buses,pay the price and buy it from MCI or it will drive you nuts with a aftermarket brand BTDT

Cliff the DL3 still uses a 3 point system just like the older ones. The second valve up front is for the kneeling system, it is a fast fill recovery for when you raise the front back up. It is not a standard leveling valve.

luvrbus · November 17, 2018, 07:45:00 AM

MCI calls it a leveling valve when it goes south the drivers corner will not raise I know that for sure BTDT

buswarrior · November 17, 2018, 08:47:05 AM

From a preventive maintenance standpoint...

If one has crapped, change 'em all and you won't look back.

Or, at the minimum, the pair for the axle, if that is the case.

The coach tells you what's wrong, the busnut needs to extrapolate that to strengthen reliability.

happy coaching!
buswarrior

mqbus767 · November 21, 2018, 08:31:43 PM

Thanks for the feedback guys.

I believe Thomas is correct per my inspection of the bus and this bulletin: http://www.mcicoach.com/service-support/serinfo/serinfo12A.htm

Correspondingly, I've order a replacement pair of the valves on the rear for $120 with shipping. They should arrive next week, so I'll update ya'll once I've got them installed.

On a slightly different note, while airing up the bus today, I noticed what sounds like a leak coming from the LH rear side engine bay. Investigation led me to the exhaust ports on two Norgren solenoids. (P/N v61r517a a313jb)The top one was exhausting quite heavily, the bottom one, not so much. My guess is that these are electronically actuated tag axle unload valves because I haven't so far been able to find the manual ball valve style ones. I searched my parts and maintenance manual for this specific run of bus and neither one of them mention Norgren at all. However, I was hoping to get some feedback on exactly what they are and why they would be exhausting constantly. (Picture attached)

The "low air tag axle" telltale is lit, but goes out fairly quickly down the road.

luvrbus · November 22, 2018, 12:39:59 AM

Those 2 valves lock and unlock the steering tag,your light should go out around 20 mphs when the tag locks in place.there is a service bulletin on the MCI web site about those,I carry spares

buswarrior · November 22, 2018, 07:34:17 AM

There is a "tag locked" indicator, different from "low air tag"...

Something wrong here, locking and unlocking of the tag steer is different from the amount of air in the tag suspension...

You need to know the operating logic for your tag steer lock, when does it lock and unlock itself, and does it light the light when operating automatically, or just when you over ride...

Or something else...

Takes a lot of words to get to the bottom of it.

Happy coaching!
Buswarrior

mqbus767 · November 22, 2018, 07:38:32 AM

Got it. Will continue the investigation and let you know. Thanks guys and happy Thanksgiving!

luvrbus · November 22, 2018, 08:02:21 AM

The 2 Norgern valves are for the rear steering lock and should not be leaking

chessie4905 · November 22, 2018, 08:08:21 AM

I'll have to check and see if my 4905 has them...lol.

Jim Blackwood · November 22, 2018, 08:17:37 AM

How does that tag steering work? Does it use an axle with kingpins for instance? With a steering tie rod and possibly a squarish looking block attached towards one end?

Jim

luvrbus · November 22, 2018, 08:20:46 AM

Quote from: chessie4905 on November 22, 2018, 08:08:21 AM
I'll have to check and see if my 4905 has them...lol.

Thankfully MCI didn't get carried away with Norgern valves like Prevost those things are expensive