atlas copco oil in the line

Questions & Answersatlas copco oil in the line
Cas Staff asked 4 years ago

Hello sir nice to find a good website like this one!

My name is rich, mechanic at a taylor rental center and we have a atlas copco tow behind model xas 96 jd screw type comp. that is blowing the safety valve and getting quite a bit of oil blowing out of the lines.

Unloader valve has been rebuilt and has fixed another problem i had with oil soaking the air filter now the filter is fine but still having the oil in the line problem.

Havent had much experience with comp. so any info on this problem will be appreciated thanks

2 Answers
Cas Staff answered 4 years ago

Hi Rich,

Glad to hear you like the website 🙂

About your problem, oil in the air is usually caused by one of the following problems:

1) Too high oil level
2) Too hot running temperature
3) Dirty/old oil separator filter
4) Plugged scavenging line

I have a feeling that number 3 or 4 is what is causing you problems.

In the small tank/air receiver inside your compressor is a filter, called the oil separator. The separators job is to separate the oil from the air, so only air is blown out and the oil stays inside the compressor.

Is that the one you changed already?

If not, change it. You need to open the vessel from the top (6 bolts or so) and replace the separator.

The other thing is that the scavenge line could be plugged with dirt. The oil separator works by making big oil drops from smaller oil drops (simply said)… the oil drops collect at the bottom of the separator.

The scavenge line sucks up the oil from the bottom of the oil separator. The oil is sucked back to the compressor element.

If the flexible hose, or the pipe (inside the air vessel) is plugged, it will not work anymore and the oil will not be sucked away, but instead it will leave your compressor together with the compressed air.

So, what you have to do: open up the vessel inside your compressor. Inspect both the oil separator filter and the scavenge line. You should be able to blow through the scavenge line by mouth (watch the oil 😉 ..

One last thing: how do you stop the compressor? Do you just shut it down, or do you follow the proper shutdown procedure?

These portable air compressors should be stopped as follows: during running, close all the oulet valves. The compressor will now go to unload and minimum speed. Wait for a minute or a few minutes. Shut down the compressor.

If you just pres ‘stop’, while you are using compressed air, the compressor will spit out a lot of oil the next time it is started.

If you want more info about diesel driven portable air compressor, be sure to check out my portable air compressors page.

Good luck and let me know if you need any more info.


Gene Emo answered 4 months ago

Hello, I have and atlas copco XAS 185 KD7. When air valves are closed tank psi is 125. If I open them gradually and keep tank psi 90 or above everthing is good. Whith the valves wide open tank psi drops to 50 and oil is blowing out of the lines. What do think the possible cause could be. Thanks Gene

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