Remember when you could just listen to a diesel engine to find the problem?

I was working on an old 7.3 Powerstroke last month that had a rough idle, and the computer codes were pointing everywhere. I spent a good two hours swapping sensors with no luck. My old mentor, a guy named Bill from the shop in Billings, always said to use a long screwdriver as a stethoscope. I finally gave up and tried it, placing the tip on each injector while it was running. On number three, the tick was way off, more of a dull thud. I pulled the valve cover and sure enough, the injector o-ring was blown, letting compression into the fuel rail. The computer saw the rail pressure swing and threw a bunch of false codes. That $2 trick from thirty years ago saved me from ordering a $300 high-pressure oil pump. Anyone else still use the old mechanical diagnosis tricks before trusting the scanner every time?

2 comments

2 Comments

riley8607d ago

Honestly that sounds like a huge waste of time. Modern scan tools give you live data and pinpoint tests for a reason. Trusting a screwdriver over actual pressure readings is just guessing.

webb.linda7d ago

Man, that's a great story. So the bad o-ring was letting compression leak in and messing up the whole rail pressure reading? I'm curious, did the scanner data show the pressure swinging all over the place, or was it just giving weird codes for other parts?