MCI 102c3 6v92ta Mechanical Won't Air Up

[Tedsoldbus]

Wow JC, Sorry you are having multiple headaches. I am NOT a mechanic and ask Buswarrior and BK and others to jerk the reins on my idea if I am sending you down a wrong path. I will take a picture of the air cylinder on my 6V92 in the morning.
Also remember I don't have an MCI but that shouldn't matter. My engine quit running a few times on a trip. (at 65 miles per hour. that was fun). Long story short I had recent service and knew I had clean fuel, fuel filters, oil was new and full, coolant full. All gages normal before shut down(s). And I had been running 5 hours before it hit.
I got two mechanics on the phone and they agreed, so I let them talk me through bypassing the engine run relay. Looked at my schematic, sent them a picture, and on the phone they had me move a wire so it bypassed it and they had me loosen one bolt on the air cylinder so I could swing it to the side to keep from shutting the engine off.
Kind of spooky because as they said it would do once I bypassed that, I had no gages and no jake until I could make it 3 hours away to a guy that replaced that relay.  Alllll better. So if you know your panel, that is a maybe, but the guys that correctly diagnosed that said that relay going bad is rare. When I told them I had new everything else, they both said check that with an tester. I did. It was bad. Probably not your problem but it shut me down. Frustrating thing was the relay was dying slowly. Intermittent damn thing. I'd rather something just crap out completely than make me chase 5 other things scratching my head.
Now you should listen to the experts. I'm guessing they will have you check fuel things...
Best of luck
Ted

[Tedsoldbus]

I just remembered a guy at the bus meet couldn't build air, couldn't find it. Nobody could hear it because it never built air. An old guy (the smart people) told him to push the big yellow air brake button to off. It aired up! It was a bad air brake valve. Probably not it again, but easy to try.
(And I learned it from an old guy, so you gotta try it.)

[luvrbus]

With water coming out the wet tank and setting for a year you may need a 10 $ set of unloader valves under the head of the compressor and a new head gasket will probably get you up and going in 2 hours. Those tiny valves rust and won't open or close. Check the easy things first like the connections on the skinner valve, It is normally closed with power no air can reach the shutdown till you kill the power and the rod goes out with air on the air cylinder pushing against the shutdown lever on top of the governor that is how the shutdown works. Make sure your rear start switches are in the right position also, those toggle switches on the rear start can be a bitch sometimes. Check the ground wire on the Skinner valve if it breaks or has a lot of corrasion it will shut the engine down,since you have air building now it and it shuts down it almost has to be electrical   

[Tedsoldbus]

Here are the pictures of what I called "the engine shutter offer" until these guys told me what it is called. Hope this helps. If you have one you CAN loosen on bolt and swing it to the side but it is there for low oil, overheat etc so I'd be cautious about disabling it to keep the engine from shutting down so you can air up. It may know something you don't...
There are better was to play with air like a compressor like Buswarrior suggested. Also easier to hear the leak without the 6V92 running.
Best of luck.

[Jcparmley]

What relay is the engine run relay?  I replaced the relay below the drivers window that usually clicks and starts the alarm until the bus airs up.  However, now that "new" relay doesn't engage.  Not sure how to bypass it but I know that I don't have power at the master switch and starter switch. 

Wow JC, Sorry you are having multiple headaches. I am NOT a mechanic and ask Buswarrior and BK and others to jerk the reins on my idea if I am sending you down a wrong path. I will take a picture of the air cylinder on my 6V92 in the morning.
Also remember I don't have an MCI but that shouldn't matter. My engine quit running a few times on a trip. (at 65 miles per hour. that was fun). Long story short I had recent service and knew I had clean fuel, fuel filters, oil was new and full, coolant full. All gages normal before shut down(s). And I had been running 5 hours before it hit.
I got two mechanics on the phone and they agreed, so I let them talk me through bypassing the engine run relay. Looked at my schematic, sent them a picture, and on the phone they had me move a wire so it bypassed it and they had me loosen one bolt on the air cylinder so I could swing it to the side to keep from shutting the engine off.
Kind of spooky because as they said it would do once I bypassed that, I had no gages and no jake until I could make it 3 hours away to a guy that replaced that relay.  Alllll better. So if you know your panel, that is a maybe, but the guys that correctly diagnosed that said that relay going bad is rare. When I told them I had new everything else, they both said check that with an tester. I did. It was bad. Probably not your problem but it shut me down. Frustrating thing was the relay was dying slowly. Intermittent damn thing. I'd rather something just crap out completely than make me chase 5 other things scratching my head.
Now you should listen to the experts. I'm guessing they will have you check fuel things...
Best of luck
Ted

[Jcparmley]

Ok, I started the bus today with no problems.  I removed the air line to the air cylinder on top of the governor and put a cap on it temporarily.  The bus aired up and did not shut off.  So now I know that it was the shut off cylinder that was engaging the shut down lever.  I still don't know why. 

I was unable to release the parking brakes because my break release button would not stay in the release position.  The only way I was able to get the button to stay engaged is when I pressed the brake pedal to the floor.  Then the button would stay engaged.  However, as soon as I released the brake petal the button would pop and the brakes would be set.  Do you think the parking break button has gone bad?  Also, why would it pop when I released the brake pedal?

[Jcparmley]

I forgot to mention that I am only building pressure to 95 psi or so even when I use a external air compressor.  I don't hear any air leaking when I walk around the bus.  I'm wondering why I can't air up to 120 psi?

[Tedsoldbus]

My parking break button will not stay down until I have 100 PSI on both gages. Might be a Prevost thing, but they don't want you trying to drive without enough air to apply breaks. I don't even try to push it down now until both gages are over 100 psi

If it started probably not the engine run relay, but if it is going bad slowly like mine, it will kick that air cylinder on in a hot minute even if you have good oil pressure and temperature. My bus has a schematic of all the relays on the inside of the door that covers them or I'd have been lost trying to figure out which one to by pass. Sounds like you may have already changed it??
Even with guys in the phone helping me I started off picking the wrong one and new it when the head and tail lights went out. Doesn't sound like you need to do that if it started but if it shuts off again maybe put a meter on that relay. NAPA should have one. The pros had me bypass it by taking the wire going into the left side and putting it with the wire on the right side. But that was a quick fix to get me to a guy with that relay (and it was his last one). Since you are not stranded I would caution against that. It killed all of my gages and the jake which was not a fun way to drive for 3 hours. I worried the whole way. You can get a new relay and change it at your place. If that is not it - be glad you are not trying to change it on I 81 with semi's flying past you and a frightened wife in the bus. That sucked.

I need to shut up and let Buswarrior, BK, Bob Glines and others that know what they are talking about help you but I hope you get it solved.
Good luck JC

[luvrbus]

I forgot to mention that I am only building pressure to 95 psi or so even when I use a external air compressor.  I don't hear any air leaking when I walk around the bus.  I'm wondering why I can't air up to 120 psi?

Try setting the pressure on the governor P>S they work opposite of most pressure regulators screw those up after you remove the rubber cover to increase the pressure.You still have an electrical problem to deal with and it will keep shutting down till it is resolved.MCI parking brakes release at 80 lbs the parking valve is not supposed to pop up till the air pressure is in the 20lbs range,where did you hook the supply line for the compressor? you may not be filling all the tanks since that is a dual air brake system and the parking brake valve is not getting a signal from a empty air tank   

[Jcparmley]

I hooked the compressor to the inlet in the passenger side rear engine hatch.  I attached it where it says "drain daily."  Is that not an appropriate place to attach the external compressor?

Here is a pic of the cylinder I removed that was shutting down the engine.  As soon as I figure out this electrical issue I will put it back in place.

Try setting the pressure on the governor P>S they work opposite of most pressure regulators screw those up after you remove the rubber cover to increase the pressure.You still have an electrical problem to deal with and it will keep shutting down till it is resolved.MCI parking brakes release at 80 lbs the parking valve is not supposed to pop up till the air pressure is in the 20lbs range,where did you hook the supply line for the compressor? you may not be filling all the tanks since that is a dual air brake system and the parking brake valve is not getting a signal from a empty air tank   

[Tedsoldbus]

Mine was bolted on each side. The guys told me to take one bolt out and loosen the other one and just turn it sideways but yours may be different. Keep it connected to air so you see it if pushes the plunger out of the cylinder even though it can no longer shut off the engine. It is at least telling you it wants to shut down. If you bypass the relay, it shouldn't activate the cylinder. When I did the bypass I lost gages and jake as the mechanics told me I would, but the cylinder did not activate all the way to the repair place (3 hours away). Again a bit touchy on doing the bypass. You are effectively hot wiring the bus and bypassing a built in shut down mechanism that is there for reasons we talked about earlier.
 If it quits while on bypass I'd say it is up to BW and Luvrbus guys to help you then -  but maybe go back to looking at fuel starvation...
I have the same thing you are talking about as far as a place that looks like you can add air. I have not tried it. I think it just fills my aux air tank that sits just below that port. I have not tried it but guess I should. I look at it as one of those "if it is not broken" things for now but I should find out before I need it.

[Tedsoldbus]

If you run the engine without that cylinder attached, and your relay is working so you have gages, watch your Oil Pressure and Temperature.
FREQUENTLY.
I don't want you seizing your engine because of advice I gave you. I know a bit about that cylinder out of necessity but I am not a DD mechanic....!
(Smart guys: jump in anytime here...).

[Jcparmley]

Someone help me by telling me what a skinner valve is and where do I find it on my bus? 

With water coming out the wet tank and setting for a year you may need a 10 $ set of unloader valves under the head of the compressor and a new head gasket will probably get you up and going in 2 hours. Those tiny valves rust and won't open or close. Check the easy things first like the connections on the skinner valve, It is normally closed with power no air can reach the shutdown till you kill the power and the rod goes out with air on the air cylinder pushing against the shutdown lever on top of the governor that is how the shutdown works. Make sure your rear start switches are in the right position also, those toggle switches on the rear start can be a bitch sometimes. Check the ground wire on the Skinner valve if it breaks or has a lot of corrasion it will shut the engine down,since you have air building now it and it shuts down it almost has to be electrical   

[luvrbus]

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 

[chessie4905]

A skinner valve is a term for an air control solenoid operated by electrical power. When power is applied the valve STOPS  pressurized air flow from your air system through it, OR when electrical power is  applied, ALLOWS air flow through it. I'm  guessing " skinner is a brand name or an expression for those valves.