Air System Help Please

[travlinman]

Hey Guys,

After much reading here on the board I am diving in on my first DIY service on my 4106. Things have been going well, I am done with the oil and fuel filters. So today I started on the air dryer service. After a bit of wresting I got the end cover off and what I found was not pretty. There is this oil water mix on the end cover and around the seal. The rest of the dryer has a light film of oil inside and the discharge hose does as well. I have been wondering about my compressor for a while now, when I drain the reservior I get a bit of oil on my fingers. SO, what do you guys think?? I am guessing this is not normal as the air dryer was serviced less than 10,000 miles ago. Thoughts...here are a few pics.

TM

[bevans6]

You do one of two things when you open up something like that - smile with satisfaction, or grimace with anticipation...  I think you did the latter.  Constant oil in the compressor discharge means a new compressor sooner rather than later.  I changed mine well before there was an issue simply for preventative maintenance (and because my engine was out), and I used a Bendix re-manufactured unit.  It was around $500, give or take.  Lets you inspect the drive gears (maybe change to steel if you have fiber), change the gasket, change the governor, replace the crusty old air hoses to the governor, probably you should replace the big discharge hose too.  Then, you've done what you need to do and can again smile with satisfaction!  Trust me, it's a good feeling!

Brian

[Joe Camper]

I would tend to agree with what Brian said and would add that your photos are about normal in terms of what I'm usually looking at when I service one. That lower chamber of the drier is precisely where all that crud should be accumulating and migrating down and out.

The first time I opened mine up the canister with the beads in it was completely empty and I was baffled. I also had mega amounts of the grey matter in the air tanks as well as the bottom chamber of the drier.

I too assumed the grey matter was oil contaminated water but I now wonder if it was what was left of the silicone beads. Since then I see nothing accumulating in the tanks at all and I see that same grey crud in dryers on vehicles way newer on a regular basis.

The newer AD9 with the spin on filters......when I service those that same grey crud exists in its base.

Another thing specific to the AD2. There is a heating element built in the base of that dryer that is not serviceable. Rebuild kits may or may not include a thermostat that many confuse with the heat element but it is not. The heating element itself is embeded in the base and is not serviceable if it goes bad you need a new base and they are getting scarce from what I am told.

To test the heating element put the base in the freezer for a while and then do a continuity test from the wire terminal to the base itself for the ground. If you have continuity the heater is working.

Definatly keep an eye on it and if you begin to drain the tanks and actually see black matter I would be figuring on a new compressor for sure.

[luvrbus]

Be sure and check the air intake source before changing compressors you see some of the 4106 tied to oil bath filters sucking oil from the old oil bath cleaners.

I had one where the owner made himself a heavy duty gasket lol and plugged the return and filled the compressor with oil and it made oil like a oil well was nothing wrong with the compressor

good luck

[travlinman]

Clifford - My bus has been converted to a paper element, but that is a good story.

Joe - Thanks for the heater tip, I will try that after I clean up the base today.

Brian - Looks like I will be doing a compressor while I have shop access, better now than on the road next summer.

OK, so where is a good source for a Bendix rebuilt compressor?  After reading about Chaz's drama I know where I will not be buying mine!!!!!  There is a Pacific Power near the shop so I think I will start there. Any other recommendations???

Thanks as always,

TM

[Boomer]

Another tip.  A lot of us have repowered our older coaches that originally came equipped with the AD-2 dryer.  In the case of repowering to the newer Cummins (and I suspect the S60 and Cat also, but does not apply to the TuFlo series) you will need to install an econ valve after the compressor.  What this does is hold pressure in the compressor after it unloads, and prevents oil from passing by the compressor rings, which winds up in the dryer.  This might trick you into thinking that the compressor is shot.  In my case (Cummins ISM) I simply installed an AD-9 dryer, which has a built in econ valve.  The cost of the econ and shipping was nearly as much as a new AD-9, so no brainer on that.  Problem solved.  Like Clifford says, take your compressor intake air from a good clean non presssurized source. Hope this helps.

[Boomer]

Steve, from the looks of the rest of your engine I doubt you need a new compressor, those old TuFlo's will go for hundreds of thousands of miles.  But if you do, I get mine rebuilt or exchanged at Brake Systems in Portland.  They will be a lot cheaper than Pac Diesel.  The oil means it's doing it's job, just service it and keep draining the wet tank IMHO.

[travlinman]

Mark,

Thanks for the info, I have a TU-FLO 600 compressor on my 4106. So from your post I would not need the econ valve? I am learning as I go here so don't be afraid to spell it out for me! Here is a pic of the compressor.

Thanks

Steve

[robertglines1]

lOOKS like recent install. Sure oil isn't left from past failure and isn't residual left over and just working it's way out of system?  Why I think so is hoses, gasket material and general apearance of compressor. Might ck rebuild tag.   Bob

[bevans6]

I agree with Bob!  I would, before doing anything else, take the discharge hose off (the air output hose directly connected to the air compressor head), clean it very well, and see if it gets soaked with oil inside.  If it doesn't, then perhaps your air system just has the remains of oil from a previous compressor.  There is a difference between a little oil making the water dirty, and oil...

Brian

[travlinman]

OK sweet, I will pull that line and see what I get.

TM

[Boomer]

No, does not apply to you Steve, that's only on the Holset compressors with an AD-2 dryer.  I doubt you need compressor work but if you ever do you could go up to the TuFlo 700 or 750.  Just service the dryer, it will clean the system up in time, might take a couple services to make the system bone dry.  You might include a purge valve kit in your project as long as it's apart.  I applaud your efforts in the maintenance area.

[artvonne]

  Okay color me dumb, but every diesel has really black, black oil. If the compressor was throwing oil into the air system, even mixed with water I would think it would be real dark blackish brown?? So does the color of slop in his drier look normal color, or is it like Joe Camper suggested, the remains of those grey silicone beads?

  A bit off topic, I asked this before but do we really need a drier? My MC5 never had one, just has a Whiskey sniffer. I'll likely never drive in freezing conditions unless something unexpected comes up, like a new grand baby or another funeral.

  It just seems like these driers are just another thing to fail, and theres always threads about drier problems and failures. Long as we blow the tanks a lot we should be okay, right??

[luvrbus]

Paul, the dryer is to collect the oil from the compressor also they not just for freezing weather 

good luck

[buswarrior]

Yes, I was expecting to see pictures with black ooze from the pits of Hades.

That stuff you've got looks routine to me, but I usually saw these in a transit environment, so my mileage may be biased....

I priced a new AD2 purge valve and desiccant kit, it comes out to the same price as a rebuilt AD9...

I fear my AD2's days are numbered, as the purge valve is shot, and extreme violence is in the cards for removal.

happy coaching!
buswarrior