I can't comment on any recommended time to replace the motor mounts, but I can share my breakdown experience involving broken/missing motor mounts:
http://rawze.com/forums/showthread.php?t...5#pid48875 (01-11-2020 )JimT Wrote: ...
Got my first load as an OO around the 25th of June. Heavy load of wooden spindles. Moved the truck to the side after being loaded, set the brakes, popped the clutch and bam, forgot to take it out of low gear first. Lots of bad words followed. Inspected the best I could but couldn't see anything broken. The next week or so I only hauled a few loads. Only weird thing I noticed was that the shifter would move a lot side to side when the engine was applying torque...
On my way home with another heavy load just after the 4th of July holiday and I messed up a shift on a steep hill about 5 miles from home. Next thing I know I'm getting low coolant and check engine alarms. Parked it before the temp got too high and ended up getting towed to a shop about 3 miles away. The torque caused the engine to twist just enough to break the plastic inlet elbow on the top of the radiator.
Come to find out that I broke the 2nd motor mount when I popped the clutch. According to the mechanic the other mount was completely missing and looked like it had been missing for a while. The only thing holding up the engine was the front mount. Yes, he replaced ALL the motor mounts along with the radiator during the repair. He also found that the remote lube hose for the clutch wasn't connected and ended up putting 2 tubes of grease into the clutch! It was much easier to operate after that.
When I bought the truck I had 2 different shops look at it, an annual DOT inspection and of course my ignorant self looked at it too. Of course I didn't know sh!t back then, so I can't just pass the buck and blame others for my ignorance.
Expensive lesson 3 weeks in to my new career. Still, that was almost $10k in total costs that should have been completely avoided, even after I screwed up with the clutch.
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