Mcrafty1 Posted August 22, 2016 Share Posted August 22, 2016 I've discussed this here before to some degree but my 86 mack E6 250 has burned down around no five piston yet again (third time in 3700 hrs. ) my question to the mack gurus here is this: although I have the fuel turned up on this engine and drive it myself can anyone explain why the same number 5 piston is the only one that fails? the other 5 piston have been in the truck three times as long as the one that failed yet show no signs of over fueling or excessive heat. Some history...The first engine failure was 10,000hrs. broken ring which ended up on top of the piston (which now looks a lot like the same failure that I keep having) the engine was inframed, fuel turned up at this time and new heads were installed(all mack parts) same nozzles, 2000hrs later same piston failed replaced that piston and liner only and replaced the nozzle thinking that that was the culpert. Started to notice some blowby around 3600 hrs.and the pump failed at that point (governor issues) so I sent it (the pump) to a reputable diesel fuel systems shop and had it rebuilt and last week at 3740hrs. no 5 has failed again...I'm really at a loss as to why the same piston is the problem every time and I'm hoping some here has had the same issue and found out how to correct it. Thanks for any and all insight into this that you have. Quote Link to comment Share on other sites More sharing options...
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