Injector stuck open, cooked a piston on I-80

Freightliner started missing hard near Joliet, smoke rolling out the stack. Pulled the head and found injector 5 stuck open, piston crown melted on one side. Anyone run into this with a specific common-rail pump causing repeated injector failures? I'm looking at replacing the whole fuel rail next.

2 comments

2 Comments

sanchez.julia2d ago

That melted piston on number 5 is classic from the high pressure pump sending metal chunks down the rail. I had the same deal on a 2018 Cascadia, replaced the pump and injectors but not the rail, and lost another injector three months later. The CP4.2 failure leaves tiny bits in the rail that you cant see unless you cut it open, so you're smart to replace the whole thing. Also make sure you flush the return line and check the fuel cooler, that's where the debris likes to hide.

wadejenkins17h ago

Fight the urge to just slap a new pump on and call it a day, because that rail is like a bad roommate that keeps the mess around after the party's over. @sanchez.julia nailed it with that tip about the return line and fuel cooler, those are the spots where the steel confetti likes to pile up and wait for round two. I swear, CP4 pumps break down like they're made of glass and then spread the love all through the fuel system just to keep you busy. Cutting that rail open is the only way you'll ever see the damage, but by then you've already lost a weekend and a pile of cash. Better to replace everything up front and pretend the old parts never existed, that's the only peace of mind you're gonna get.