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Author Topic: URGENT (again!) -- Air system failure, even more stranded now...  (Read 3637 times)
technomadia
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Zephyr - 1961 GM PD-4106-446


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« on: September 30, 2011, 09:24:47 AM »

Ok - it happened again, and our theory yesterday is wrong - it is not the high pressure safety valve.

Slowing down at an intersection just after leaving camp this morning, there was a pop, and now I know that the noise was our air brakes popping and engaging (simultaneous with the air warning alarm going off).

The pressure had dropped instantly to 30psi again.  I got safely off the road, and unlike yesterday - this time the air pressure did not climb back to 110psi on its own.

Revving the engine to 1500rpm, I can barely get the air pressure back up to 55psi.  If I drop to idle, the pressure drops down to 30psi.

Walking around the coach - the governor on the air compressor may be the issue.  It is leaking air, and continues after the engine stops.  There are three plug holes on the back of the governor.  The bottom is not plugged, and has air coming out.  This was also open yesterday - I have no idea if it supposed to be this way, or whether the plug fell out.

Anyway - we now can't build up pressure to drive, and are on the road right outside Monument Valley.  We had made an appointment at the diesel garage in Durango this afternoon, but now are about to call in Coach Net.

Any help appreciated - call 408-667-9022.

   - Chris
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Cherie and Chris / www.technomadia.com
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technomadia
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« Reply #1 on: September 30, 2011, 09:32:18 AM »

Some more observations...

When I first put the new air compressor air filter on, I was impressed with how much quicker our bus aired up.  But yesterday morning, the bus aired up slowly - it stuck at 30psi for a while, until I put the bus in fast idle.  Once it got to 110psi, it was fine and held pressure.

Today - the same thing happened - the bus sat at 30psi for a long while until I gave it a lot of throttle to air it up.

I am certain this is related to the failure we've experienced the past two days.

I am thinking the governor's over-pressure relief valve may be sticking open.  Yesterday it popped back shut.  Today it isn't.

I am going to saturate the governor with WD-40, and try to find the manual to figure this one out.

But if you have ideas - please call.  Thanks!

   - Chris
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Cherie and Chris / www.technomadia.com
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travlinman
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« Reply #2 on: September 30, 2011, 09:39:57 AM »

Hey Chris,

Are you sure that the governor is your only leak? When you say air brakes popping and engaging I'm wondering if one of your air brake cans is bad? I'm around this morning so give a call if I can be of help. I'm looking for my governor manual now....

Steve
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Steve & Kristen Full time nomads since '06 - PD4106-674  8V71/V730
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« Reply #3 on: September 30, 2011, 10:00:11 AM »

Chris, don't you have a governor on the spare compressor that is in the bay the port that is leaking is the exhaust port it is open no plug   

good luck
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technomadia
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« Reply #4 on: September 30, 2011, 10:04:39 AM »

We just checked that actually, Clifford - there is no governor on the spare compressor.  (Good memory!!)

 - Cherie
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Cherie and Chris / www.technomadia.com
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technomadia
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« Reply #5 on: September 30, 2011, 10:12:00 AM »

Ok.. lubbed up the exhaust port on the governor, did a little percussive maintenance... turned the engine on. And she's airing up normally, and no more whooshing of air out the governor.

*crossing fingers*

 - Cherie
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bevans6
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« Reply #6 on: September 30, 2011, 10:13:49 AM »

everything you ever wanted to know about a D2 governor (D2A is just non-adjustable D2)

http://www.bendixvrc.com/itemDisplay.asp?documentID=5644

The only time air is supposed to come out the exhaust port is when the governor is transitioning to cut-in, when it has to dump the air in the unloader port to let the compressor start to compress again.  If it is dumping air continually, then it is broken.  Probably the inlet/exhaust valve has some junk in it, or an o-ring has cracked.

I would get a new one, it's about the most common air thing that you can possibly ask for at a store.  If it's a D2, that is.

Brian
« Last Edit: September 30, 2011, 10:16:20 AM by bevans6 » Logged

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luvrbus
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« Reply #7 on: September 30, 2011, 10:27:24 AM »

The D2A is adjustable Brian you do it with shims they can be set to cut in at 5 lbs below max pressure used in construction equipment where there is not much tolerance for air pressure drop on the air controls,I ran one on my bus for years because I didn't like the cut in pressure for the D2 mine was set on 125 cut in was 117   

good luck
« Last Edit: September 30, 2011, 10:37:48 AM by luvrbus » Logged

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travlinman
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« Reply #8 on: September 30, 2011, 10:35:01 AM »

Just as a side note, how often should I replace my governor? Seems like a read a lot of posts where these go out!

TM
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Steve & Kristen Full time nomads since '06 - PD4106-674  8V71/V730
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« Reply #9 on: September 30, 2011, 10:40:28 AM »

Tm, those are supposed to be part of the pm if you service the D2 they don't give problems most neglected item on the air system so they go south,only cost you a 1.25 and 15 minutes of time but people wait till they quit on the road lol 

good luck
« Last Edit: September 30, 2011, 10:43:56 AM by luvrbus » Logged

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travlinman
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« Reply #10 on: September 30, 2011, 10:47:55 AM »

Luvrbus,

I read the D2 service manual and it sounds like the PM consists of testing the unit for proper operation and checking for leaks. Is there anything else you do? Would you replace this unit on a time schedule or wait until it fails a test?

Thanks

TM
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Steve & Kristen Full time nomads since '06 - PD4106-674  8V71/V730
bigjohnkub
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« Reply #11 on: September 30, 2011, 10:55:00 AM »

You should carry one in the bay.  Cost me $12/15 at NAPA>
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Big John  Tyler Tx PD 4903-188 & 4107
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luvrbus
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« Reply #12 on: September 30, 2011, 11:01:37 AM »

TM, they will show when they are going bad just like Bendix's SD-01-16 says, me I cleaned mine 1 time a year and replaced the o-rings 1.25 is abetter to me than 15 or 20 bucks and looking for one knock on wood never had a failure or replaced a D2A like you read here Bendix has to love these guys here lol


good luck
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skihor
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« Reply #13 on: September 30, 2011, 01:31:06 PM »

coach net will pay for a service call. You are responsible for labor and materials @ around $125 + or -

Don & Sheila
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Busted Knuckle
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« Reply #14 on: September 30, 2011, 02:11:24 PM »

Rather than opting for a service call I'd have coach net tow it to the shop they already had an appointment at for service.

Other wise they could be paying a service guy to "chase" parts all day time and mileage.

Just my way.
Grin  BK  Grin
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Busted Knuckle aka Bryce Gaston
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