Each month in Diagnose This! we present a real-life service scenario with clues as to what the ultimate diagnosis was. If you think you know the answer, be the first to e-mail Dsmith@rrpub.com with the correct response for free Truck Parts & Service merchandise. The answer will be revealed in a future issue of the magazine.
This month’s Diagnose This! is submitted by ASE master technician and owner of Fleet Guardian, Damon Russell.
If you have a Diagnose This! puzzler you would like to submit, please send it to Dsmith@rrpub.com.
Vehicle: Older Ford L8000
Key component: RT7608LL Roadranger transmission
Scenario: Customer complained of a knocking sound that suddenly occurred while the truck was in traffic on the interstate. The knocking sound happens only when the clutch is up.
Technicians determined the knocking sound was coming from the transmission, which was removed.
After removing the cover off the transmission, the source of the noise became apparent, as evident in the photo.