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?

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.


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.

Ingersoll Rand Up6-40-125 40 Hp 125 Psi Rotary Screw Air Compressor
Ingersoll Rand Up6-40-125 40 Hp 125 Psi Rotary Screw Air Compressor


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.