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Bus would not air up
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Any chance you took picture of the part he removed ? How did he determine this part failed ?
Trying to help you.
AL
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update:
They took the part off. Took it back to their shop. Blew it out with an air hose. They said it appeared to be stopped up. They clears some obstruction. Brought the part back to the coach and reinstalled it. Cranked the engine up. Still no air in the primary and secondary systems other than the 25 psi that was there before they did anything. Next they undid the air line coming out of the air compressor at the engine. Started the engine and told me there was no compressed air coming out of the compressor. Said compressor was bad. Trying to get a new one locally from the Detroit diesel shop here in Hobbs, NM. Tomorrow is Saturday so we may not have things going again before next week. Will take a photo of that air valve and post it here if anyone is interested.
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The good news is your retention of pressure in the primary and secondary tanks shows the check valves and protection valves are working.
Sorry about the compressor though because they are a little pricey.
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This is the valve they took off and cleaned. When they removed this valve all the air in the auxiliary system drained. There was also water dripping out of the black hose attached to the right side of the valve.
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You never want to see moisture in your air system. Your coach has a dryer downstream from the compressor and it has a cartridge to trap moisture. Downstream from that is what is called a “wet” tank. You might get a bit of an oil / water mix, perhaps a tablespoon full from time to time from that tank.
Every other tank downstream should be dry.
Because you got moisture from the accessory side of the system it indicates water generated by the auxiliary compressor is passing into the accessory side of the coach air system. I imagine the water traps downstream from the aux compressor have a lot of moisture in them because they have not been drained.
If the water has backfed into the accessory air tank and further into the accessory side of the system that moisture can be very damaging to the suspension, especially the valving. You should get that checked ASAP by someone that knows Prevost coaches.
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As Jon said oil/water in the air system is bad. With a failed compressor I would recomend replacing the air dryer cartridge asap and draining all tanks……
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The local repair facility here in Hobbs is trying to come up with a new air compressor. They say the old one is not outputting air. We are thinking that they haven’t checked to see if the air compressor governor is bad. Yesterday they couldn’t find the governor. What they found was just the auxiliary pressure regulator (see photo in my previous post). They just took it off, messed with it and brought it back and hooked it up again. We don’t think they’ve found the governor. We have found a picture of the governor in the parts book we have in the coach. We have found the description of the air compressor and governor in the maintenance manual. What we haven’t found is the actual governor. Does anyone know where it is actually located on our coach?
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Try looking on the backside of the compressor, that is where mine is.
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My compressor is a Bendex BA921. According to the parts manual the governor is suppose to be located where three holes are in the rusty area of the attached photo. The photo is of the cylinder head view with the camera facing the back of the coach. There is no governor there. I’m beginning to think there is no governor for this compressor anywhere. Am I correct? Does that center hole lead to the unloader piston?
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GPSMen……
If you haven’t found the governor at the compressor is is probable you have the Haldex dryer which has the governor built into it. It is mounted on the bulkhead forward of the drive axle I think. It will have a clamp holding the cartridge in place that has four screws as opposed to the previously used Wabco dryer with the spin on cartridge.
I’m a little concerned your service guys are spending so much of your time and money doing on the job training. I’m more concerned they might not have a clue.
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If the tech does not know the difference between a APR and governor I would be worried the governor will be in air dryer it’s built in like Jon said if it’s not on compressor
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What you are saying is so true. They haven’t returned today yet. Probably because they cannot find the BA921 air compressor. I believe you are correct in that the governor is built into the Haldex dryer. We’re wondering if the dryer can be accessed without raising the coach. We are sitting here at an RV park. The service facility is 4 miles away. If we could get to the dryer we would try to do something with it. We’re just wondering how our compressor could work without a governor?
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Yesterday, the service guy disconnected the air output line from the compressor. Started the engine and he said that air was not coming out. So, how could anything else matter if the compressor is not making air? Could it be that the unload pistion in the air cylinder head is stuck open?
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Jon,
I too am concerned that the service guys are doing on the job training, and *very* concerned that they might not have a clue. We are trying to learn enough about our engine to *stop* them if they start doing something that will cause even more damage.
What we really do not understand is that the mechanic disconnected the air output hose from the compressor, we started the engine, and the mechanic said that no air was coming out of the compressor output port. What could cause this to happen? If no air comes out of the compressor, could anything else matter?
We made a guess that the cylinder head of the compressor has an unloader piston in it, and that the unloader piston has somehow come open and stayed open. Could there be an unloader piston in the cylinder head if there is no governor to actuate it?
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The whole problem could be in the dryer which essentially controls the compressor.
Can you reach it while in a CG. Yes.
First I am going to guess you can adjust your aux compressor cut out and cut in pressures. Get your aux air built up and try to raise the rear of the coach using the aux pressure as it is set. If the cut out pressure is too low to raise the rear of the coach, adjust the pressure to no more than 120. That will certainly raise the rear as high as it will go.
Then put supports under the body support points. If the ground beneath the coach is gravel or blacktop or thin concrete distribute the load with some planks. A good hydraulic jack with an adjutable center screw is a safe support. A Hydraulic jack that has been pumped up is not, but in an emergency that might have to do.
With the rear of the coach up, you can slide beneath the coach. Then you can sit up.
Here is what you have to recognize. With the key off and any automatic leveling feature off such as on an HWH system air is locked in your air bags. But anytime anyone goes under a coach and is working on the pneumatic system you are at risk. I don’t know your coach and here is where other Vantare owners need to jump in to make sure you are not going to have the suspension come down when you turn off the key. But if it does the chassis supports will be your safety device so take them very seriously. Do not get beneath the coach until the chassis is supported as a back up to the air bags.
If you are beneath the coach ALWAYS remember to not put yourself in the position where if the coach drops you are in a pinch point. Even with the suspension air locked in place and the chassis supports in place. There is a lot of height and room for you to sit up once under there.
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