Trusted Contributor
Trusted Contributor

Re: 3608 Oil sampling location

The usual location for taking oil samples is one of the plugs on the manifold at the top front of the engine below the oil temperature regulator housing.  This is flowing oil for a good oil sample and should not be a place for sediment to settle out and compromise an oil sample. 


I would send in a sample of new oil and see if the lab can determine whether or not the new oil is contaminated.  That sometimes happens during the handling.  It could be that the oil drums, the transport vehicle, or your storage tanks are contaminated.  If so, this will require diligence to make sure the cleaning process is complete.  Further, the oil in a gas engine should not be "black".  Black oil is usually the result of soot which is a byproduct of combustion.  This is normal for a diesel engine but not for a gas engine as there is little or nothing to create soot as a combustion byproduct that will contaminate the color of the oil.  Make sure that there is no other connection into the engine oil piping which could contaminate the engine lubricant.  I have seen mistakes made from time to time where an incorrect piping was made that resulted in some contamination like this.  Complex pipings systems lend to confusion in which pipes should be connected.


A thorough system assessment will be necessary to make sure of piping integrity as it sounds like an external issue and not one from inside the engine, unless the engine was reassembled under dirty conditons.  This could also be a possibility.


Best Regards,

Al Hunt


3608 Oil sampling location

Howdy to this board and this is my first question.


Where do you pull an oil sample from on the engine to submit it for an analysis?


We are using Mobil Pegasus 805 and the engine was recently overhauled (about 6 months ago).  I'm not sure if this started with the first sample taken after the overhaul or when Mobil changed their oil analysis program lately.  We keep getting reports that say " The sample is heavily contaminated with visible sediment.".  We have sent the samples to other labs and they do not make that comment.  And after resampling the oil, I think it was the third or forth time, the sediment did not show up again.  Then on the last sample the comment reappeared.  I went over with a new operator, the one that had been taking the samples left the company, and watched him take a sample.  The valve is at the front of the engine near the top and I think it is tapped into a heat exchanger.  Is that a good place to be sampling the oil?


I put some of the latest oil sample on a piece of clean white paper.  The oil is pitch black.  I smeared it around with my finger and could not see or feel any sediment.  I don't have the analysis report back from that sample yet so I don't know if it will be flagged for high sediment levels.