Bus Mechanical help thread.... non-urgent (with pics)

[philiptompkjns]

So, I just got a 102a3  for a pretty good price, there are a few things wrong with it that I've been working on.
First off some of my  background...
I have a bit on experience  working on cars/boats/airplanes.  I've done engine  swaps on all but only have engine rebuilding experience on rotary engines.
I've swapped entire car drive trains, from the engine to the whee hubs.
I do not however have hardly any diesel or air systems experience but I am working on learning.
Any help you guys could give me is greatly appreciated, anything from troubleshooting to the best place to buy parts.
I do have both the  maintenance manual and the parts manual on hand but and especially terrible  at figuring out electrical diagrams.

Now on to what I have at hand.
I found 2 air leaks in the engine  bay, one  at this air cylinder that pushes on this lever (governor? I used this lever to shut the engine down).
It seems like in certain positions this cylinder leaks air, and in other positions it does not, I'm guessing that it's never supposed to leak air and needs to be replaced or rebuilt.


This valve is also leaking a little air, it seems to control air for the belt tensioning  device for the a/c compressor.  I'm not even sure if I'm going to keep the bus  air right now, the switch for that on the dash is broken (anyone have one of those?) Can I replace that  valve with a home depot air valve?


And when I bought the bus it  seemed like the solenoid or relay that the "master" switch is controlling was kind of  sticky, like it would not shut down right away (hesitate  for  a  second or two) or  it would not power up if the voltage was even slightly  low.
Lucky for me the solenoid got stuck in the ON position today, to shut the bus  down I pushed the lever that is shown in the first  pic in. That seemed to work pretty well because the bus actually  started back up after that.
When the master switch was working I could hear a loud clicking coming from the  back of the bus, now I don't... could someone point me  in the right  direction on that one?

The bus is a 1990 102a3 with a  6v92

Thanks for reading and any help will be greatly appreciated.

[luvrbus]

The 2 items in the photos are a easy fix clean them up and replace the o/rings.
Check your power to skinner valve on the fire wall that supplies the air to the shutdown if power is there in the on and start postion and you don't get a clicking when turning the switch off and on try cleaning it also it will not work for shutdown without around 90#s of air.
If the skinner valve is bad I replace the shutdown and skinner with the all in one unit from Detroit cheaper around 80 bucks

good luck

[RickB]

Heed Clifford's advice (aka luvrbus) and if you find that the fuel shutoff solenoid is too wore you can order a kit form CandJ coach here in Minnesota nine five two 881-0034 ask for Fred.
Also, since the shutoff operates on air your bus will not shutoff until you have enough around 90lbs of air built up in the system.

welcome aboard,

Rick

[philiptompkjns]

I guess I should have been more specific. 
When turn the master switch off nothing  turns  off, like  the gauges ect. do not power down.

I'm fairly convinced that this particular problem is electric because before, when  the bus had NO air whatsoever, I could hear it clicking somewhere in the back when I flipped the  master on and off.... I think that this relay is stuck ON.
anymore ideas?

[Iceni John]

How come a 1990 6V92 apparently is MUI?   I thought by then they were all DDEC II.

Just curious.
John

[Jriddle]

This what is was for me.
http://www.busconversions.com/bbs/index.php?topic=14518.0
And then this thread.
http://www.busconversions.com/bbs/index.php?topic=14563.0
Sounds like you may have two problems?

John

[Busted Knuckle]

How come a 1990 6V92 apparently is MUI?   I thought by then they were all DDEC II.

Just curious.
John

No John many folks were reluctant to go DDEC and MCI and Prevost both were the last to go strictly DDEC up till then it was which ever the customer wanted is what they put in them from '88 or '89 to '93-'94 !

[philiptompkjns]

The 2 items in the photos are a easy fix clean them up and replace the o/rings.
Check your power to skinner valve on the fire wall that supplies the air to the shutdown if power is there in the on and start postion and you don't get a clicking when turning the switch off and on try cleaning it also it will not work for shutdown without around 90#s of air.
If the skinner valve is bad I replace the shutdown and skinner with the all in one unit from Detroit cheaper around 80 bucks

good luck

Ok lvr,  I'm pretty sure  that it is an electrical issue that I'm having because when I  turn the master off, not only does the engine not  shut down but the dash power stays on.  If the shutdown valve  were not working  wouldn't the power to the dash  turn off when I turned the master off and the engine  stay running?

[Nellie Wilson]

Acronym Question: What's MUI?

IYDMMA (If you don't mind me asking).

Nellie Wilson

[lostagain]

Mechanical Unit Injector, I think. Mechanical for sure, as opposed to electronic: computer controled.

JC

[edroelle]

The belt tensioning valve that appears to be leaking - 

The root cause of the problem may not be the valve.  (If it is, Luvrbus is right, just change the O rings.)   The problem might be the the air cylinder itself.   Air leaks by the air cylinder seals, back to the valve, and the valve allows air to bleed as it is suppose to.  You can diagnose  the problem by removing and capping the air lines to the cylinder.  If you still have leakage at the valve, the valve is the problem.   After chasing this problem around, I had a cylinder seal that sealed intermittently.

Ed Roelle
Flint, MI

[Hartley]

Ground Your entire Dashboard and side panel fully.

Maybe that will help eliminate the phantom switch failures....

It's an MCI and they ALL have bad dashboard/relay panel grounds (eventually)...

Dave...

[philiptompkjns]

ahhh that could be... got any advise on the best way to do this? I'll be tearing into it this weekend.