Oil in Compressed Air Tanks and under Air Dryer

[Jerry Jayne]

What I have is an issue with some oil coming out of all 3 purge valves when I purge my air tanks monthly (normally done to see if any water is present).  No water comes out, just a bit of oil as a mist and some droplets.  My Beaver Contessa is 6 years old with 40,000 Miles.  I have NEVER had any oil come out in the past, either with this coach or the one before it.  I have discussed the issue with an over-the-road trucker and he suggested a little oil coming out could be considered normal and suggested I just ignore it.  But I don't want to have a bigger repair down the road by ignoring a warning sign now.  Perhaps my Air Compressor is letting way too much oil past the rings when compressing and the Air Dryer isn't catching it all and expelling it all when it "Purges".  Thus it's being passed further down-stream to the air holding tanks.  Then it could get into any equipment or systems using air from the tanks and cause real problems.   Or maybe its just a matter of opinion on what is "too much oil getting through" .  What I am experiencing is this:  when I open each purge valve, if I hold my hand in front of the discharging air ... I will get such an oily residue on my hand that I have to wash it off.  Happens on all 3 valves.  And there's an oily mound on the metal surface where the Dryer "unloads".  And the air compressor has a slightly different sound before it "unloads" than it had when new.   But, it builds pressure in the "normal" amount of time so nothing seems strange there.  And it seems to "cycle" on-off just as normally as when it was new.  In reading forums, some people are reporting that ANY oil (or water for that matter) getting past the Dryer to the holding tanks and coming out the purge valves means the dryer needs servicing (new cartridge if water is present) or the Compressor needs rebuilding (oil is getting past the rings).  I don't know how to judge what is "acceptable".   Can anyone give me advise, or do I just take it to Caterpillar and let them figure out what to do?  Thanks in advance,
Jerry Jayne,  42'  '09 Beaver Contessa, 425 HP CAT C-9, 40,000 Miles.  Chicago, ILLINOIS,  312-576-1048

[Joel Ashley]

Though our coach is older than yours, it has fewer miles;  Henderson's suggested changing the filter on ours this fall at 17,000 miles.  I'd surmise that at 7 years and regular use, it's time for air dryer service, Jerry.

Joel

[Keith Moffett]

The idea of putting oil in the air system is common.  I understand it is intended to protect the inside of the air tanks.  I cant say regarding that but it could be someone has used too much.

[Jerry Jayne]

Thanks, Joel, for the reply.  One of my concerns is if I just replace the WATER Desiccant Cartridge (e.g. "service the air dryer") but I have an issue with bad rings in the compressor itself (letting oil get by) then I wont have addressed the issue ... possibly only hiding it temporarily until the new cartridge "fails" because of oil saturation, or by just bypassing oil to the air tanks.   I'm trying to understand what is an acceptable amount of oil coming out of the Compressor with the pressurized air.  I'm now looking into buying a better air desiccant cartridge that also traps oil (it's also an oil coalescing cartridge) to see if that will cut down on the oil getting to the air tanks.  But, I'll listen to anyone's ideas.
Jerry

[Jerry Jayne]

Thanks to Keith also.  My reply:  No one put oil in the air system, it got there by coming thru the air dryer from the compressor (Accidentally, or from failing rings in the compressor).   It's not supposed to be there because if it goes downstream to other air systems (like brakes) it can ruin them.
Jery

[Lee Welbanks]

Jerry,  Disconnect the main air line from the compressor to the dryer and fire up the motor and see if you are getting oil coming out of the line. I would think that the filter should be full of oil if it is getting into the tanks. I have never had a compressor go south in all my years trucking but I guess it will happen.

[Gerald Farris]

Jerry,
It is impossible for me to tell you from your description if you are getting too much oil from your tank bleeders or not. However, if you are as concerned as you appear to be, my suggestion would be thoroughly service or replace the air dryer or take the coach to a trusted diesel service facility to do so if you do not feel qualified to do it yourself. This should be the most cost effective way to address your issue.

Some oil discharge in the compressed air is normal and it is removed by the dryer as long as it is not too excessive, and I doubt that a 40,000 mile coach would have excessive oil discharge from the compressor. However, it is possible especially if the engine is using a lot of oil, but if you are not using engine oil, I do not think that you have a compressor problem.

Gerald     

[Jerry Jayne]

Thanks for the advise and thoughts.  I have ordered a replacement Desiccant cartridge for my Dryer and will inspect the installed Cartridge (for oil) when I do the change.  What I ordered is the WEBCO Desiccant Cartridge that also has an Oil Coalescing capability.  Maybe this will make things a little better than just the Water Desiccant Cartridge which is probably what is installed now.  When it arrives I will do the R&R and will know more.  I'll run with it a while and see if I still accumulate a small amount of oil in the air tanks.

Thanks, also, for the idea about looking for Oil in the direct output from the compressor.  I'll have CAT look at that too if I end up taking it to them.
Jerry

[Jim Edwards]

Just a thought. If people make Oil Coalescing filter, then I would suspect that this is common enough issue that someone engineered and marketed a solution. Webco Meritor is not a small concern.  I might suggest to contact Webco tech support (phone number on attached) and ask them how to check the filter/system for oil. The attached brochure indicates 2 yrs or 200,000 miles. If the filter is failing more quickly it may give you a gauge on how bad your issue ("leakage"?) might be. I cannot say for Motor coaches but in air driven systems that I worked on for many years, we always has oil separators after the compressors because we could not allow oil contamination blowing out of the air cylinders into the process. The process was water based and the oil from the compressors did not mix well at all.

Good luck.

I might just get one of these for mine!

[Chuck Jackson]

You've obviously seen a change in the pattern and more than likely the compressor is starting to show oil blow-by but I guess only a mechanic will really know if it is too much. Based on your description is doesn't sound like a serious problem yet but could be in the future. I think you are smart to at least have it checked out now rather than later.

For what's worth, I have very little water and/or oil (more of a quick mist) coming out when I drain the tanks but during my purge cycle it does make a mess on the sheet metal platform underneath after a while...to the point that I made a PVC down tube to redirect the air/oil/water that comes out during the purge cycle. The research I've done indicates (to me) that some oil and water out of the purge port is normal and any water/oil in the tank means the desiccant filter needs to be changed.

[gregott]

I know this topic is a little old but looking for any updates from those experiencing oil from air dryer. I have '08 contessa 425 c9, replaced both the turbo and the compressor last April as well as deleting the problematic dpf. I am experiencing what I think to be excessive oil purging from the air dryer covering the curbside rock guard with oil. Also getting a bit of oil spray when purging the air tanks. I have an appointment to have my mechanic check it out as the compressor is still under warranty. Wondering if anyone has had good luck reducing the oil purged when using the oil coalescing filter? Any other ideas as to a potential cause of this problem? Or maybe just normal for this engine? Thanks

[Dave Atherton]

Greg, moisture mixed with a little oil look like you have problem but this is normal. Air dry filter
Is keeps popping off to purge moisture every 20 seconds it is a good idea you need a filter change.
If you let go to long your pop off valve will not seat and many times you cannot build up any
air pressure and this happens when you stop on the road and cannot build any air pressure to go.
If oil you feel is excessive and engine oil is going down than problem is within the air compressor
of which is very unlikely. Dave Atherton Retired Cat Mechanic.

[Gerald Farris]

Greg,
Let me put in my 2 cents worth here. A slight amount of oil is normal as the air dryer purges, but from your description, yours sounds excessive. I do not see where a filter change is going to reduce the oil in your dryer purge. If the air compressor is using oil (mixing oil into the compressed air), that oil has to go somewhere, so it will either be in the air tanks or in the dryer purge stream. So the only question that I see here is are you getting excessive amounts of oil, and since we are not there to see the coach, that is a question that will have to be decided between you and your mechanic.

Gerald