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Author Topic: Air problems  (Read 6861 times)
compedgemarine
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« Reply #15 on: September 09, 2008, 08:27:40 PM »

I had a similar problem a while back on a Kenworth tractor. I went to change the dryer cartridge and found a lot of oil/water/sludge in it. prior to us getting the truck the compressor had gone out and been changed but no one cleaned out the oil it pumped into the system. I had to pull the dryer apart and flush the line from the compressor to the dryer. after all the crap was out the dryer started to function as designed and everything worked again. so in answer, yes, if the dryer is full of goo then it can cause all types of problems.
while the early A2 and A3 dryers are good I was told by a friend in the truck parts business that parts are getting tougher to get and if it failed on the road I may have to spend a couple of days waiting on parts so I replaced mine with a new AD-IP unit with the spin on dissacant cartrige.
good luck
steve
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quantum500
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« Reply #16 on: September 09, 2008, 08:33:36 PM »

Thats what I thought although I can't get my mind around why.  What is the best way to clean and/or check the function of the purge valve off of the governor?
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compedgemarine
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« Reply #17 on: September 09, 2008, 08:42:59 PM »

I dont know how to test it but I cleaned mine with brake clean. I took apart everything I could to make sure everything that was supposed to move would after cleaning. the first question would be if there is that much goo in it where did it come from. generally the goo is from oil in the system. while there is always a tiny bit of oil if there is enough to goo up everything then I would think that either the compressor is tired and pushing oil through it or the dryer has been ignored for way to long. I found my AD-IP dryer on ebay for $150 new from a company the sells lost/abandoned freight. for that price it wasnt worth it to me to deal with a 26 year old unit.
steve
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quantum500
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« Reply #18 on: September 09, 2008, 08:56:13 PM »

If I think about things on a postive level I don't think I have ever heard the purge valve let go.  With over 2000 miles of driving under my belt who knows how long the previous owner let it go.  I'll see about parts, I have a really good supplier locally.  The cleaning of the line could be a challenge.  Its about 35ft long and not at all accessible.  Sometimes I wonder what MCI was thinking?  They go over the top on actual material and then make things hard as hell to service.  Maybe some high pressure ethonal?  Gotta make that stuff pay for my high food prices somehow.
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luvrbus
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« Reply #19 on: September 09, 2008, 09:03:57 PM »

Q500, if you have all the crap in your system the air dryer needs service bad that is  the purpose of it. If you have the AD 1 or Ad 2 change the desiccant filter and clean the valve as per Steve parts are available for them  at Napa the desiccant filter are a exchange at Napa for around $35.00 the valve is easy to clean and very seldom give problems .The Bendix web site will show how to service it with all the parts numbers. good luck
« Last Edit: September 09, 2008, 09:23:35 PM by luvrbus » Logged
quantum500
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« Reply #20 on: September 09, 2008, 09:47:25 PM »

Thanks luvrbus that was part of the plan.
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Sojourner
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« Reply #21 on: September 09, 2008, 09:48:44 PM »

Here an attachment of a MCI-8 air system schematic.

About the AD1 or AD2 dyer with purge….Non purging is either line is disconnected from governor, governor inoperative or worn out or it could be piston froze in purging valve area. Usually governor problem.
http://www.bendixvrc.com/itemDisplay.asp?documentID=3604

Bendix D-2 Governor:
http://www.bendixvrc.com/itemDisplay.asp?documentID=2382

There is 2 small air line from governor…one to purge’s piston and the other to top half of air chamber of air dyer to tell governor when to stop air build up and purge at the same time.

When it working properly…it will purge when air pressure reach the cut-off point at the governor.

About replacement of your air dyer (Ad-1 or AD-2)….make sure you get the automatic purge type like you have now. I could be wrong but I believe class 8 don’t have automatic purge as buses do.

FWIW

Sojourn for Christ, Gerald
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JackConrad
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« Reply #22 on: September 10, 2008, 05:24:55 AM »

Here is a ping tank.  The large hose entering the side of the tank is from the compressor. The large hose exiting the top of the tank goes to the wet tank/dryer.  The small hose coming off the bottom is the drain and should be drained daily. The quick connect fitting is something we added to allow connecting to our shop air (through a double male fitting).  The blue DOT tubing connected through the one way valve is from our aux. air compressor.  Jack
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quantum500
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« Reply #23 on: September 10, 2008, 07:13:59 AM »

Thanks for the replies.  So after Jacks picture of the ping tank I have checked that out thoroughly and have no blockages.  I may or may not have time to check it out some more today but I'm getting closer to the source of the problem. 
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quantum500
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« Reply #24 on: September 11, 2008, 09:28:03 AM »

I made some progress yesterday.  I found out that my governor is not makeing enough pressure to purge the air dryer.  I hit the purge line to the dryer with shop air about 10 or 15 times and got a huge puddle of goo to come out.  Everything seems to work correctly now.  I need to repair or replace the governor and service the dryer thanks for all the help!
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Sojourner
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« Reply #25 on: September 11, 2008, 09:06:57 PM »

quantum500....Here a link to AD-2 dryer from Bendix:
http://www.bendixvrc.com/itemDisplay.asp?documentID=3604

About replacing governor....you may not have compressor's inlet filter or missing or worn out. I would get the update version filter assembly. Poor filtering or none will cause wear to compressor's piston & cylinder wall and wear out the governor. I would be concern about compressor yet until see how oil drain out from ping tank.

This will explain how much oil usage is normal on page 4:
http://www.todaystrucking.com/images/BendixCompressor%20TroubleshootBW1971.pdf

BTW....is the air relay exhaust show oily & wet? Two in rear and one in front.

FWIW

Sojourn for Christ, Gerald
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Ps 28 Blessed be the LORD, because he hath heard the voice of my supplications. The LORD is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him
hargreaves
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« Reply #26 on: September 11, 2008, 11:19:13 PM »

Q500, I would look seriously at the compressor,with that much goo it seams as though the compressor is passing a lot of oil. If the goo gets into the relay valves and further along the brake chambers, you are in for a lot of work and money,   let alone a system that at best is marginal.

Good luck,     Gerry.
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quantum500
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« Reply #27 on: September 12, 2008, 10:03:43 PM »

The compressor gets air right out of the main engine air filter.  So I don't understand what I could update too.  I have in the past drained the ping tank on a regular basis and I haven't gotten much if anything out of it.  The relay exhaust does not show any oil residue.  I think that the problem I figured out has been going on for a long time.  Like I said earlier I have never heard the purge on the dryer go off.  I didn't really think about it in the past because I thought the dryer was closer to the compressor which would make it hard to hear in a bus, but as I found out it is very close to the drivers seat and I should be able to hear it most of the time.  So in reality it could have been a problem long enough that it finally showed itself in this peculiar way.  I did get a chance to take the governor apart tonight and it had a chunk of rtv sealant wedged inside of it between one of the valves.  I took it out as best I could but I think the valve is stuck and there is no way to take it part any farther that I can see.  So that would explain the lack of purge action, and it still does not purge!  Another point to ponder is the region I live in which is very arid so while condensation does happen its not nearly as much as most people would see.  I'm sure the compressor isn't perfect but I think if everything is working correctly I shouldn't have any trouble with it.  I will keep you posted.
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Sojourner
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« Reply #28 on: September 13, 2008, 12:18:30 AM »

Quantum500, thank for your up date.
About air intake connect to engine’s filter is better yet.

About governor and 2 small lines. Being you already found rtv or whatever in governor…it possible have a plugged purge line, try blowing via air gun one line at a time so you won’t misplace where the line goes back on. The other line is pressure signal line, it could be plugged with water rusted inside,,,,try to air gun it to see if it clear at the other end.
Maybe purge line is leaking some where along the line. Pressurize it with plug at the other end and hand-held pump with gauge from auto parts store.  It should hold pressure steady.
The pressure-signal line is under pressure while air in dryer, you may hear it leaking, if not then it good.

D-2 governor…I would go to any heavy duty truck place or NAPA for replacement. They cost about $20. It well worth it and easier than repairing it plus you know it should work.

Model D-2 is use on many trucks with air brakes.

Reinstall with thin coat of # 3 Permatex onto cleaned compressor surface & governor.
http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Aviation_Form-A-Gasket_No_3_Sealant_a.htm

MITYVAC VACUUM PUMP AND BRAKE BLEEDING DELUXE KIT
 http://yhst-13811118617756.stores.yahoo.net/mty-7000.html?productid=mty-7000&channelid=BCOME

Keep posting update till fix.

Sojourn for Christ, Gerald
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Ps 28 Blessed be the LORD, because he hath heard the voice of my supplications. The LORD is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him
John316
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MCI 1995 DL3, DD S60, Allison B500.




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« Reply #29 on: September 13, 2008, 08:02:17 AM »

Quantum 500,

I haven't posted much, but we have had a somewhat similar situation with our MCI DL3.

If you were thinking about replacing the compressor, I would recommended replacing the governor, rebuilding or replacing you whole air dryer first, then if you are still getting significant oil through replacing the compressor. When our compressor went, we were getting a lot of oil out of our tanks. The only caution is if you replace the dryer before the compressor, and if the compressor is bad and sends a lot of oil through the system, then you just ruined your new dryer (not to mention oil is hard on your brake diaphragms etc.)!!! Also be careful with shop air, if the pressure is greater than your coach is regulated for you can blow your brake diaphragms and other pressure sensitive parts.

We replaced the governor, compressor, dryer, and blew out all the lines, which fixed our problem.   

FWIW HTH

God Bless, John  
« Last Edit: September 13, 2008, 11:14:24 AM by John316 » Logged

MCI 1995 DL3. DD S60 with a Allison B500.
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