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Re: 3608 Oil sampling location

Dwight, I am at a loss as to what is making your oil black.  It is a bit difficult for me to visualize what you have.  I think of black oil like what you have in a diesel engine.  The soot from combustion turns the oil black pretty quick.  But gas engines don't produce soot from combustion so the oil stays a lot cleaner (lighter in color). 

 

I just don't know what the source is.  I don't think the color of the oil in itself is a problem but not knowing what is causing the darkening, I can't say that it does not contain something that is harmful to the engine.  The oil samples look pretty good.  I recommend that the TAN be watched so the oil doesn't get too acid.  Of course, air/fuel ratio has an effect on nitration, which can cause some darkening as can oxidation.  So these two observations are a check on engine setup and operation with regard to emissions and temperature.

 

The only other thing that I can consider is the remote possibility that someone has inadvertently connected a line or pipe incorrectly and this is feeding something into the engine lube oil that might be causin this discoloration.  I just don't know.

 

Best Regards,

Al Hunt

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Re: 3608 Oil sampling location

I just got the oil analysis reports back.   The old oil was drained, and the crankcase was wiped clean.  No deposits were found in the crankcase.  The filters were changed and no porblems were found with them.  Of course you can't get all the oil out of the lines and heads, so once the new oil was run for 24 hours it again becomes the same color. The lab now explains that it is too dark for the particle analysis laser to pass through and that is why they can not do a particle count on the sample.  We sent off three samples and they are:

1. As found

2. Fresh oil fron the storage tank

3. After 24 hours of run time

 

Is it worth the cost of the oil to flush the engine with clean oil?  I think it would take two or three flushes, complete oil changes, in a row with very short run times between each to clean out the oil system.

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Re: 3608 Oil sampling location

I am glad to hear that the oil is being changed.  Cleaning out the oil pan with careful inspection to see if there is any debris/foreign material in the bottom of the pan is important.

I probably would take an oil sample after a 24 hour engine operation.  That should be enough to have everything in the oil system have full circulation to move any remaining sediment to the oil filter elements.

I wish you success.  I am interested in what you find and what the success is.

 

Best Regards,

Al Hunt

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Re: 3608 Oil sampling location

Finally got word that operatioins is going to drain the oil and clean the crankcase out on Feb 8th.  The engine is in an enclosed building and I should be able to stop by that afternoon to see what it looks like.  At that same time a new dedicated oil sample line will be installed.  It will beinteresting to see how long the oil stays clean and if a new sample taken maybe a week after the change shows any high levels of sediment.  Do you think a week would be long enough or should it even be sampled a day after the new oil is in?

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Re: 3608 Oil sampling location

Thanks again for your help!  I just emailed the oil analysis reports to you.

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Re: 3608 Oil sampling location

The Cat recommended oil and filter element change interval is 5,000 hours.  But in gas compression, it is common for customers to run the engine oil for a year (8500 hours) using oil sampling with no issues and very little darkening of the oil.  And I have seen several different brands of oil in my years of experience.  The oil gets darker than when it is new, but not appreciably darker.  Now the filter change period of 5,000 hours should NOT be extended or you run the risk of filter(s) collapsing and contaminating the complete lubrication system and a high probability of serious engine damage if the elements become too plugged and come apart.  There is NO filter bypass valve on the G3600 like other Cat engines so you don't want to have the elements come apart.

Now the port, tube, etc. should always be flushed sufficiently to be sure that there is no residual uncirculated oil left that would be caught in the sample bottle.  Also, if the sample line was not flushed enough, the residual material could be enough to cause the sample color to look darker if the lab technician did not carefully evaluate the visible conditions of the oil sample. 

You are correct that the engine oil is sprayed up to the bottom of the piston crown for cooling.  In addition oil is forced into the cavity in the piston crown and exits down on to the upper portion of the con rod and piston pin.  But unless the oil gets really hot and run too long, this oxidation would cause some discoloration but I would not think I would describe it as black.  The oil would have to be really bad to be called "black" from oxidation.  And I don't believe the oxidation numbers on the oil sample report support this condition.

I am sorry your oil representative is not responsive.  Apparently he is not fully aware of the potential cost of a major failure.  I think many of our techs don't fully realize how much the G3600 engines they work cost.  I would be glad to review another oil sample.  The other sample report was not very readable.  You could send it to my email address as an attachment; hunt_al@cat.com.  That might come through in a more readable condition.

I hope that my comments help.  I was responsible for a dealer oil lab operation for about 10 years so I have some experience in this area even though I was not the lab technician.

 

Best Regards,

Al Hunt

 

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Re: 3608 Oil sampling location

The oil is changed when an analysis report shows a need to change it.  I don't know if they are changing the filter at those hours.  Looking through the manual I noticed that the oil is sprayed up against the bottom of the pistons to cool them.  That would cause the oxidation and discoloration of the oil, though I don't know just how dark it may make the oil get.

 

I am going to have them install a dedicated oil sample line with a 1/4 turn ball valve at one of the other spots available on the oil thermostat housing.  I think the previous person getting the oil samples may not have been flushing enough oil through the line.  I watched the new person and they did not flush the line enough and also turned the valve off, then back on to fill the sample bottle.  That could cause sediment to enter the sample.

 

I am wondring if the noted 'high visible sediment' comment is refering to the color of the oil.  I cannot ever get any questions answered from our contact at Exxon Mobil.  He hasn't ever replied to any of the many emails I have sent, nor has he ever returned a phone call, much less answer a call.

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Re: 3608 Oil sampling location

I'm pretty sure the hours listed on the oil are wrong because it was changed to get rid of the potassium problem.  The mechanics found a leak and fixed it and the potassium level hasn't come back up.  It's just the "high levels of visible sediment" that I am concerned with...and now the black color of the oil that you are indicating is wrong.  Thanks for all your help!

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Re: 3608 Oil sampling location

This is the latest oil analysis, the one we took a few days after receiving this report hasn't arrived yet.  I don't see any reason for the oil being black, do you?  I am going to look at some Clarks tomorrow to see what color the oil is.

 

2015-12-28 Oil Analysis p2.jpg2015-12-28 Oil Analysis p1.jpg

 

 

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Re: 3608 Oil sampling location

Dwight,

This is the correct place to take an oil sample with the engine running.  The needle valve proably works okay if you flush out the valve/line with the first oil and then take the sample after that.  A ball valve would be a little bit quicker.

Again, gas engine oil should not turn black like diesel engine oil does due to the lack of soot as a product of gas engine combustion; there just isn't anything to turn the oil black on a gas engine.  So if the oil is really black, something else is going.  Oxidation of the oil might lead to some darkening of the oil but if the oil is getting too hot, I would expect you to see a high oil temp alarm.  How often do you change the engine oil?  The recommended oil change interval on a G3600 is 5k hours but customers routinedly run the change interval to yearly (8500 hrs.) with no problems.  You should NOT run the oil filter change out past the recommended filter change interval of 5K hrs.  If you do, the filter element might collapse and then all of that debris goes into the engine.  There is no oil filter bypass valve on the G3600 like all of the other Cat engines.  So if the filter gets plugged, it will eventually just collapse instead of opening the bypass valve, which is not on the G3600.

Best Regards,

Al Hunt