CM870 Burned piston

[Rawze]

(09-23-2022 )Hemiterry Wrote:  I have an 2006 International 5600 dump truck with a CM870. Last week it died on me while idling and my mechanic found two leaking injectors and a worn gear pump. I had him replace the gear pump and all the injectors while he was in there. I picked up the truck and went straight to the gravel pit and got loaded with 15 tons of gravel. The truck ran great until I pulled out onto the highway which was at a steep incline. It immediately started running rough and barely had enough power to get up the hill to a place where I could pull over and get out of the road. After I got stopped the truck died and was spewing coolant out the cap and was at 230 degrees. I had it hauled back to the shop and they discovered the engine wouldn’t bar over. They pulled the valve train and removed the injectors and discovered #1 cylinder piston had a hole in it and was seized. They’re thinking the new injector is bad and was over fueling the cylinder causing the burned piston. They’re sending it to an independent lab to be tested. The injectors came from FleetPride but were not Cummins OEM. I don’t know what brand they are yet but I’ll find out. Does all of this sound legit and if the injector isn’t defective could it be improper installation or adjustment on the mechanics part ? Any input would be appreciated.

It could be that the injector arm torque was not set correctly.. or that it could have been a bad injector.. but the more likely scenario is no one pulling a hard vacuum on the coolant system after the injector replacements, etc.. and it had some trapped air around that cylinder (or possibly the injector itself), overheating the cylinder badly.

I have seen that time and again.. (burnt piston, sometimes a warped liner, or sometimes a cracked liner) and a shop will cover its arsse with all kinds of excuses like "we never pull a vacuum, never have that kind of trouble" and other horse-s#it when confronted with weather or not they pulled a hard vacuum on the coolant system before releasing the engine to you.

-===

your description leads me to believe that is likely what happened... If no one pulled a hard vacuum on the system and you went from no/light load t(which can take half a day of driving to drive all the air out of the coolant system like that when a shop was too lazy to use a vacuum) to full operating load very shortly after the coolant system was filled back up, then the likeliness of a catastrophic failure like that becomes VERY HIGH.

just an alternative set of thoughts.. Like I said.. I have seen it too many times...

SO....

proper procedure IS TO ALWAYS, ALWAYS PULL A VACUUM ON THE ENGINE TO REMOVE ALL AIR FROM THE COOLANT SYSTEM AFTER ANY WORK IS DONE AND THE COOLANT SYSTEM WAS DRAINED, EVEN A LITTLE BIT!.

you should ask them "what is your procedure for filling the coolant system back up"... and if they say anything less than "a full vacuum" then there is your most likely culprit... The SHOP!.

ref: http://rawze.com/forums/showthread.php?t...7#pid16787
ref: http://rawze.com/forums/showthread.php?t...1#pid31591
ref: http://rawze.com/forums/showthread.php?t...4#pid55774

Not saying that is definitely what someone did... its just the highest likely guess based on what has been said .. , just iterating that it is a common mistake that shops do and take for granted waay too often, eventually leading to someone paying the price.

-====

There are other causes of cracked pistons too.. bad fuel-air-mix due to over-spooling turbo, incorrect injection timing, and some other things, but most of those are associated with a bad delete or turbo acting up (above 40-lbs boost), etc.. and there are usually signs of something wrong before it gets to that point.