Found out why my injectors kept failing, it was the fuel cooler bypass

Had a 2018 Freightliner with a Cummins that kept eating injectors every 40k miles. I checked fuel pressure, filters, even the pump, and it all looked fine. Finally a guy at a shop in Tulsa told me to look at the fuel cooler bypass valve. It was stuck open and the fuel was getting way too hot, which messes with the injector lubrication. Replaced that valve for $85 and the injector temps dropped back to normal. Anyone else seen this bite them on a similar setup?

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wright.lisa16d ago

Wow, that's a sneaky one! I read a tech article a few months back about heat causing injector issues on those newer Cummins motors. It said guys always chase the fuel pressure first but the cooler bypass can get stuck without throwing any codes. I had a buddy with a similar problem on his T680, and it turned out to be the same thing. It's crazy how something so cheap can mess up parts that cost thousands to replace.