MCI 102c3 6v92ta Mechanical Won't Air Up

[Jcparmley]

After reading past posts on the subject of the skinner valve, I believe my valve is not getting power.  The rear start toggle switch is not getting power.  This I believe is the answer to all current problems.  I don't have power getting to the start circuit.  I have another thread on the same topic so I will be checking that and everyone's help is much needed and very much appreciated. i will jump to that other thread and read through that. 

Your C has 2 mounted on the wall in the engine compartment above  the engine 1 is for the fast idle the other is for the shutdown both have a 2 wire plug with 1/4 in copper tubing for air supply ,does the fast idle work ? the skinner is doing it's job when the power is off it is shutting the engine down, you get power to rear start and I think your problem is solved inside the rear start there are relays and fuses,the engine safety shut down could be problem also if you have a override button on the dash it flips up to reset the system.

Van bought me the best relay tester for my birthday it so simple plug the relay in push a button and it tells all, no wires to deal with it is a HECS 200-2000 tester

[Jcparmley]

Ok, so I still haven't figured out the dash power but I did get a chance to work on the air system.  So I found two major air leaks.  A fitting broke off the rear tag passenger air bag air hose.  The other was in the spare tire compartment.  A small air hose broke off and the air fitting as just blowing air.  So I caped both of the air leaks and couldn't find anymore.  However, the bus still wouldn't build pressure above 75 psi, even with an exterior air compressor hooked up.  So could it possibly be the air compressor governor?

[freds]

Ok, so I still haven't figured out the dash power but I did get a chance to work on the air system.  So I found two major air leaks.  A fitting broke off the rear tag passenger air bag air hose.  The other was in the spare tire compartment.  A small air hose broke off and the air fitting as just blowing air.  So I caped both of the air leaks and couldn't find anymore.  However, the bus still wouldn't build pressure above 75 psi, even with an exterior air compressor hooked up.  So could it possibly be the air compressor governor?

No you still have massive leaks somewhere. An external air compressor should be able to fully air up the bus.

[buswarrior]

No you still have massive leaks somewhere. An external air compressor should be able to fully air up the bus.

Ditto. Never mind the whizz bang complicated distractions.
Keep looking, You have leaks.

How are all these lines breaking off? Something wrong here...

Happy coaching!
Buswarrior

[luvrbus]

Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak

[buswarrior]

Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak

Or, being lazy, i would try to hold the parking control button in the released position while trying to build air. Block the wheels first, of course...

If nothing changes, this does NOT rule out the DD3 as leaking, but is an intermediate diagnostic trick that might save some screwing around. You can't count on the inversion valve to perform correctly under these circumstances, but it is easier than crawling, if it does expose them leaking.

Happy coaching!
Buswarrior

[luvrbus]

Because the way air tanks are mounted a rusted out air tank with a pin hole is hard to detect too,you may need a larger compressor for more volume to find leaks.I use freon and sniffer sometime, the sniffer will pick up the freon in the general area for a leak then you can pin point it  good luck it is not all fun and games finding some leaks. You can take the compressor out of the loop too the unloader valves can stick and circulate the air into the engine crank case and those are impossible to hear.If you have a small compressor, I would rent a larger unit 3 to 5 cubic ft is not much air supply on a brake system on a bus without running the engine compressor (12CFM)   

[Jcparmley]

I'm not sure how the line broke off.  I heard the air blowing and wiggled my way between the tires and noticed the air bag wasn't filling.  So I reached up and felt the air line and sure enough, it was blowing air out of the 90 degree elbow that goes into the top of the airbag on the passenger side tag axle. 

Ditto. Never mind the whizz bang complicated distractions.
Keep looking, You have leaks.

How are all these lines breaking off? Something wrong here...

Happy coaching!
Buswarrior

[Jcparmley]

Cliffard

What is the best way to pinch the lines? 

Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak

[luvrbus]

Cliffard

What is the best way to pinch the lines?

Pinch pliers they look like vise grips only with round bars instead of jaw,Habor Frieght or Amazon

[Jcparmley]

Ok. I hooked up a larger air compressor put a chock under the wheels, and held in the break release button and the bus still wouldn't air up past 75 psi. The drive axle bags have air. The tag bags do not. The only air I hear is the air going into the air dryer. During the spring I replaced the air dryer and I checked the instructions and know I have it installed correctly. I know the tanks are getting air because I can release air when I pull the valve on the bottom of each tank. The engine is not on so I know it's not the compressor.  What are your thoughts?

[chessie4905]

Is the compressor far enough away so you can listen for air leaks?

[luvrbus]

Ok. I hooked up a larger air compressor put a chock under the wheels, and held in the break release button and the bus still wouldn't air up past 75 psi. The drive axle bags have air. The tag bags do not. The only air I hear is the air going into the air dryer. During the spring I replaced the air dryer and I checked the instructions and know I have it installed correctly. I know the tanks are getting air because I can release air when I pull the valve on the bottom of each tank. The engine is not on so I know it's not the compressor.  What are your thoughts?

On the C between the manual 2 dump valves for the tag there is a plug you can remove and try to air up the tag,there is also a electric dump valve in that plumbing to dump the air from the driver's seat,that valve maybe stuck or turn on dumping the air, it is all on the passenger's side at the engine compartment you can see the wiring and plug going to the electric valve and the 2 manual valves be sure they are closed

good luck 

[Jcparmley]

My air compressor is a 100 feet away and I can hardly hear it when it's running.  This afternoon I removed the air compressor discharge hose and hooked my external air compressor to the discharge line heading straight into the air dryer.  I figured this would tell me if my engine air compressor was the problem.  It still wouldn't air up beyond 75 psi.  I did hear air filling the air dryer.  So I decided to jack the bus up and block it.  I then crawled under and found a major leak in the hard line going from the air dryer to the wet tank.

The copper line had a hole in it. I cut the copper line above the hole and got a new copper compression sleeve.  However, I can't find the correct fitting to go from the copper line to the air dryer.  So I thought I would just remove the copper line and make a new line to go from the air dryer to the wet tank.   Tomorrow I will remove the copper line from the wet tank and have a diesel shop make me a DOT approved line to go from the air dryer to the wet tank.  However, I can't seem to find in my manual what size fitting I need for the wet tank.  Do any of you know what type of threaded fitting goes into the wet tank?  I am assuming its NPT.  The DOT Nylon Line and fitting is compression, so I will need compression to NPT. 

[buswarrior]

Take all the wreckage with you to the hose shop, lay it on the counter, and they'll fix you up.

Nothing we tell you is more accurate than what you unwind out of the fittings.

Happy coaching!
Buswarrior