by Darnell
(Honolulu, Hawaii)
I have Oil and an oily smell in the tank drain water? When I drain the air tank, red milky water comes out. Smells like oil or coolant is
mixing with the air. What else can be done or checked?
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Darnell, make of compressor? Model number? Age? Hard or light use? What color is the oil in the sump?
I can’t specifically help you without specific information on the compressor as not all are the same.
Please provide more information as a comment to this post.
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by: Darnell
It’s an Ingersoll Rand. Ser#PG0499U04019, Model# UP6-40-125, moderate daily use for production. The oil is Dark in color, had some grittiness to it when I drained some out. There’s also oil discharge from drain.

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Darnell, this is an air cooled, 40 HP, 125 PSIG output rotary screw air compressor.
While I suspect that you have an issue with your oil separator, I’ll leave details to those with actual experience on these air compressors. Anyone have advice for Darnell?
Anoter visitor has water accumulating in the sump oil of Ingersoll Rand compressor
by Dave Giles
(Auckland. New Zealand)
I have bought (12 months ago) a new 2 stage Ingersoll Rand compressor.
The problem is that water accumulates in the sump oil until the compressor starts to squeal. This is how it first came to our attention.
Three times we have undone the filler to find it over flowing. We have drained it, found water mixed with the oil, refilled with clean oil.
when restarted it sounds great an obvious change in pitch.
My colleagues suggest that running for approx 2 minutes at intervals of 15-20 minutes minimum to approx 30 minutes or so is about a good run time for a large industrial piston compressor.
Additional oil reading:
- Air Compressor Oil Capacity Guide – Air Compressor Oil Levels
- How to Change Air Compressor Oil – Guide to Replacing Compressor Oil
- Air Compressor Oil Types GUIDE – What Oil to Use in Air Compressor
- Air Compressor Oil Sight Glass – Oil Level Sight Glass Guide, Replacing & Reading
- Air Compressor Oil Related Issues – Oil Damage To Compressors
- Air Tool Oil Substitutes And Alternatives
- Air Compressor Oil Substitute – Alternatives Compared
- Oilless Air Compressors vs Oil Compressors – Differences Between Oil and Oil Free Air Compressors
- 10 Best Air Tool Oils
- 10 Best Oil Free Air Compressors
- How to Quiet An Oilless Air Compressor
- Air Over Oil – Air Over Hydraulic Cylinder Benefits & Uses
- Air Compressor Oil Breather / Crankcase Breather Cap Buying Guide
- Air Compressor Oil Separator Guide – Air Oil Separators & Oil Water Separators
- What Happens if an Air Compressor Runs Out of Oil?
- Air Comes Out of the Oil Fill Cap
- Compressor Has an Oil Issue
- Why air coming from our compressor has bad smell same as burned oil
- Why does oil come out of the oil fill tube?