Oil anal­y­sis can pre­vent a cri­sis

Motor Equipment News - - DIESEL PARTS & SERVICES -

En­gine oil anal­y­sis can de­tect a num­ber of en­gine op­er­at­ing prob­lems. One prob­lem which can be de­tected and ad­dressed is the ex­cess soot and un­burned fuel caused by ex­ces­sive idling. But just how does ex­ces­sive idling pro­duce ex­cess soot and un­burned fuel and how do these af­fect diesel en­gine op­er­a­tion?

A diesel en­gine re­lies on high tem­per­a­tures to op­er­ate ef­fec­tively. Atomised diesel fuel is sprayed into the hot, dense, com­pressed air in the com­bus­tion cham­ber and starts to va­por­ise and burn. A diesel en­gine work­ing un­der load is op­er­at­ing at its max­i­mum tem­per­a­ture, and the en­gine and the fuel in­jec­tion sys­tem are de­signed to work best at these higher tem­per­a­tures.

When a diesel en­gine is idling, it op­er­ates at lower com­bus­tion cham­ber tem­per­a­tures. This pro­duces an in­ef­fi­cient fuel burn. Lower com­bus­tion cham­ber tem­per­a­tures lead to the pro­duc­tion of ex­cess soot and leave some of the fuel un­burned. Both ex­cess soot and un­burned fuel have an ef­fect on the lu­bri­cat­ing oil and on the op­er­a­tion and life of the en­gine.

A diesel en­gine pro­duces a lot of soot, so a diesel en­gine oil ad­di­tive pack­age con­tains a lot of dis­per­sant ad­di­tive. The dis­per­sant dis­trib­utes con­tam­i­nants through­out the en­gine oil, hold­ing them in sus­pen­sion un­til the oil is drained and they are re­moved.

How­ever, the dis­per­sant in a diesel en­gine can only sus­pend a lim­ited amount of soot be­fore the soot starts to drop out of sus­pen­sion and de­posit on sur­faces through­out the en­gine. Soot which de­posits in the ring grooves in­ter­rupts the ef­fec­tive op­er­a­tion of the rings and en­gine oil starts to weep passed the rings and gets burned.

In­creased oil con­sump­tion can be a sign that the en­gine oil needs chang­ing. Soot can also be de­posited in the en­gine’s oil gal­leries, if these be­come blocked then bear­ings will run without oil and pis­tons won’t get a cooling spray of oil up un­der their crown, bear­ings and pis­tons will seize. When the dis­per­sant ad­di­tive in the diesel en­gine oil be­comes over­loaded, the oil needs chang­ing. The more idling, the more soot is pro­duced, pis­ton rings won’t op­er­ate ef­fec­tively and pis­tons may over­heat.

Un­burned diesel will tend to wash the lu­bri­cat­ing oil film from the cylin­der wall. This can in­crease wear on both the cylin­der wall and the rings, re­sult­ing in the need for ear­lier than planned over­haul. Un­burned diesel will also di­lute the en­gine oil through­out the en­gine lu­bri­ca­tion sys­tem.

But all is not lost if for some op­er­a­tional rea­son you can­not re­duce en­gine idling. A pre­mium oil anal­y­sis pro­gramme can de­tect an in­creased level of soot in the oil, will high­light oil thin­ning and changes in the oil’s flash point be­cause of fuel di­lu­tion, and will draw at­ten­tion to in­creased wear metal lev­els.

By mon­i­tor­ing trends over a num­ber of sam­ple re­sults, your lubri­cant com­pany’s tech­ni­cal per­son­nel will be able to sug­gest op­er­a­tional or main­te­nance changes for your diesel en­gines, al­low­ing you to avoid the detri­men­tal re­sults of high idling op­er­a­tion. A shorter oil ser­vice life will prob­a­bly be rec­om­mended.

But re­mem­ber that an oil anal­y­sis pro­gramme will also high­light other po­ten­tially dam­ag­ing con­di­tions your en­gine may en­counter. Coolant leaks into the en­gine oil, oil ox­i­da­tion due to con­tin­ued high tem­per­a­ture op­er­a­tion, or air cleaner fail­ure al­low­ing dirt to en­ter the en­gine lu­bri­ca­tion sys­tem would all be de­tected with reg­u­lar oil sam­pling and anal­y­sis. Dis­cussing your oil anal­y­sis re­sults with your oil sup­plier’s tech­ni­cal staff will con­trib­ute to the ef­fi­cient and prof­itable op­er­a­tion of your diesel en­gines.

To learn more about oil anal­y­sis visit www.trans­diesel.com or call Steve on 0800 848 267

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