Hi there, I'm after some advice from you very clever people. We have a Komatsu D65 PX-15 dozer that when the engine is at normal operating temp has a very rough idle, not so bad that it is hunting but sounds as though it has a large camshaft fitted.....sounds real cool and but is not right. When the revs are brought just about idle it then becomes a sound like its missing on a cylinder....above that RPM it revs as per normal. The engine will idle perfect when cold. The engine will also blow excessive black smoke from the exhaust then rev'd, the smoke will clear a little when sitting at constant RPM but still has black smoke. The amount of black smoke seems to be getting worse. A little history about this machine. The machine is used daily for aprox 8 hours, it is serviced every 250hrs by the local Komatsu guys. The engine was rebuilt around 1500hrs ago because of the engine becoming tired. The machine has new injectors fitted around 1000hrs ago to try to solve this black smoke and idle issue, which did not solve it. It has new fuel lines from tank to injector pump fitted. New throttle control pot fitted, new air and fuel filters, clean fuel and top end tune carried out with no improvement. The dozer has just under 12000hrs on her but am unsure if this is a true reading. Having spoken with the operator this morning, he believes the machine is down slightly on power but then again it might be the ole placebo affect. Any help would be great.
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