Oil in air lines

[ronwalker]

After finding black engine oil in the air I bled from the rear bleed port and in the air dryer, it seems obvious it's time to replace the engine mounted air compressor. After I replace the compressor and air dryer cartridge, what action should I take to remove oil from the air lines? Blowing solvent through the line from the dryer to the rear bleed port while it's disconnected seems innocent enough since residual solvent won't find its way into any Norgren valves or other critical components to swell "O" rings, but what if I find oil in other lines? Do I stand a chance of making the potential problem of gummed up valves worse by attempting to clean oily air lines? Would you experts out there just blow clean dry air backwards through disconnected line segments or leave bad enough alone and just watch for oil at the valve exhaust ports? I would anticipate that engine oil might make Norgren valves sluggish in cold weather or cause the rubber rings to swell and stop the shuttle valves altogether, but what other problems are likely if the oil has gotten past the air dryer? How much of a nightmare may I be facing?

Is there enough cost difference to warrant shopping for a heavy compressor at a local truck parts shop instead of having one shipped from Prevost Parts? Thanks for any answers or comments you might have for a newbie who is about to get a comprehensive air system education.

[garyde]

Hi Ron. The air lines should be dry, clean , and free of any liquids. I would say to clean and dry out the lines with something which will not leave a residue.
Also, remove any norgren valves where they may be in line with your cleaning first so as to not damage the o rings.
What to use, maybe denatured alcohol.
http://en.wikipedia.org/wiki/Denatured_alcohol#Purpose

[ronwalker]

Hi Gary. Denatured alcohol sounds like the answer I’m looking for. Most of my pneumatic system may be clean since I’ve never found more than a trace of liquid in the wet tank, but I’m concerned about the gobs of oil that nearly stop the air flow when I open the bleed valve in the engine bay. Do you get the same? Is that oil a valid measure of compressor ring wear or is air output, i.e. recovery time, the only criteria for replacement? My recovery time seems fine. How many miles should a compressor last? Mine has 350K.

[Orren Zook]

Ron,

I think your air dryer should have captured most of the oil in the desiccant cartridge, is there evidence of oil at the exhaust port of the dryer? At 350k you are approaching the life expectancy of your compressor. Oil in your air system has the potential to damage all rubber components - not just o-rings. Check with local heavy duty parts houses on pricing, if you are considering rebuilt there will be a core associated with the sale so you'd have freight both ways on mail order shopping. Buying new, no core but probably more than twice as expensive. The info on your compressor should be on a 2x2" tag riveted to the side of the compressor, reading something like TU-FLO 5xx (type) and 2xxxxxx (the 6 digit compressor part number). Change the governor while you're at it - they are cheap.

[merle&louise]

Ron,

I think your air dryer should have captured most of the oil in the desiccant cartridge, is there evidence of oil at the exhaust port of the dryer? At 350k you are approaching the life expectancy of your compressor. Oil in your air system has the potential to damage all rubber components - not just o-rings. Check with local heavy duty parts houses on pricing, if you are considering rebuilt there will be a core associated with the sale so you'd have freight both ways on mail order shopping. Buying new, no core but probably more than twice as expensive. The info on your compressor should be on a 2x2" tag riveted to the side of the compressor, reading something like TU-FLO 5xx (type) and 2xxxxxx (the 6 digit compressor part number). Change the governor while you're at it - they are cheap.

Orren,

Changing the governor is good advice; I had a governor completely fail (bad air leak). It was so bad that I couldn't put my coach in gear. Had road service come out and bring me a new governor. Easy to change. My coach required a 120 psi governor.

It is also a good idea to carry a spare 120 psi governor in your spare parts bin.

[ronwalker]

Orren & Tuga, Good advice all around... thank you. There is some oil on the dryer exhaust, but it's not slobbering all over the frame as yet, so it's probably a reasonable sign of compressor aging and worthy of my immediate attention. Yep, it's a TU-FLO 750. I'll replace the governor and keep the old one in my spare parts kit.

[Charles Spera]

Ron,
For the $25 or so that a new one costs, I wouldn't bother keeping the old one. Just buy two new pieces when you get around to the change.

[ronwalker]

Chuck,
You're right, of course, why save one to limp home on and do the job twice when for pocket change, you can replace it just once and be done with it? A new one is cheap insurance and there's no shelf life issue like there is for rubber parts.

[JIM CHALOUPKA]

Just buy one Ron, your old one lasted 14 years. Add that to your age and comprehend the likelihood of changing it out yourself at 88. :p

Lew told me to say that. :cool:

[ronwalker]

Hey, Jim, watch your addition. I'm still a spring chicken yet! Lew is an instigator. At 88 I'll still be on my hands and knees trying to get my flooring just right. 'Shoulda started building this motorhome when I was 12!