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cumminsdr, Mechanic
Category: Construction and Road Equipment
Satisfied Customers: 3643
Experience:  Cummins field tech
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Qsk23 in Komatsu 375-5 engine locks on start when warm

Customer Question

Qsk23 in Komatsu 375-5 engine locks on start when warm rattles blows white smoke but my main problemi is fuel us. History bough dozer 2011 with 3500 hr. At 4000 hr operator commented on hard start when warm .komatsu told me it was fitted new injectors . Dozer ok for about1000 got slow and I was operating and fueling machine myself.way to heavy 100 litres hr when it should have been around 75 to85. Komatsu have checked controllers. I have fitted pressure gauge to advance rail .when motor turns. Of pressure rises slowly to 80 psi then bleeds down it is then when it locks on start.what I don't get is why when you decelerate psi hits close to300 psi .at8000 hrs I bough new injectors from Komatsu And talked to cummins Toowoomba branch about my problem and stated how I need a expert. Dozer after new injectors fitted still high on fuel but worse on start with white smoke taking longer to clear . Having both sets of injectors still .i noted on close inspection with glasses that the second ring was letting fuel bypass from return to supply side . After finally getting cummins and Komatsu to admit that there was a problem with rings I have been removing and fitting a larger ring and trying to inspect injector bore for damage .what is noticeable is bores show rough machine marks not polished like a normal hydraulic fit. Now note that the new injectors did have the new harder o ring. These rings ok on removal I feel the heads may. Be sad. I did have a day after fitting the new rings that fuel use was back to 75-80 l hr. With concern that the high advance pressure on dexelation could be a factor I made a valve that held the pressure back. This valve works ok but still high on fuel .next step do I pull intake manifold of and pressure test each head to work which ones at fault. Is it possible that the new injector is faulty . Can you help.
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  cumminsdr replied 1 year ago.

what is the engine serial number?

Expert:  cumminsdr replied 1 year ago.

Hi just following up. do you need more assistance

Customer: replied 1 year ago.
Engine Serial Number 313720.
Expert:  cumminsdr replied 1 year ago.

I would have Cummins come out and check the injectors first before the heads. Since you have new injectors installed there is a warranty on them. I have installed many failed injectors out of the box. The Cummins field tech will troubleshoot and repair as needed. an if your still not satisfied have the Cummins/Komatsu Field service engineer(AKA DFSE) come out and look. All would be covered under warranty

Expert:  cumminsdr replied 1 year ago.

Please don't forger to rate my service

Expert:  cumminsdr replied 1 year ago.

Hi just following up. Please don't forget to rate my service.

Expert:  cumminsdr replied 1 year ago.

please don't forget to rate my service

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