mackr1989 Posted October 29, 2014 Share Posted October 29, 2014 Our 88 r690 makes a grinding/squeeling sound coming from either the transmission or clutch while loaded when backing up steep hills. It continues to steadily move without slowing down or stopping. What could this be? Quote Link to comment https://www.bigmacktrucks.com/topic/37527-grinding-noise/ Share on other sites More sharing options...
gearhead204 Posted October 30, 2014 Share Posted October 30, 2014 does it have a 12 speed trans? of so the rear countershaft bearings in the rear section are failing. we tore out two transmissions building a steep fill stock pile, we were backing the trucks 6 -10 truck lengths up hill and that was enough to starve the rear bearings of oil on the two upper countershafts. This was a spongy fill and required much horsepower to climb.. Quote Link to comment https://www.bigmacktrucks.com/topic/37527-grinding-noise/#findComment-264954 Share on other sites More sharing options...
mackr1989 Posted October 30, 2014 Author Share Posted October 30, 2014 It has a 6 speed low hole Quote Link to comment https://www.bigmacktrucks.com/topic/37527-grinding-noise/#findComment-264996 Share on other sites More sharing options...
Rusty Bolts Posted November 2, 2014 Share Posted November 2, 2014 just a thought, did you check the drive line, might be the carrier bearing or a universal joint. Quote Link to comment https://www.bigmacktrucks.com/topic/37527-grinding-noise/#findComment-265307 Share on other sites More sharing options...
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