What's that clunking? Bad tranny mount? [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: What's that clunking? Bad tranny mount?


chevota20
12-31-2009, 02:34 PM
Alright, for the past couple months a minor pop when driving around corners or over little bumps has grown into a series of moderate bumping under my truck when going over light dirt roads or over speed bumps. In the last month i have noticed a hard grinding noise a few times when i hit a bump or take a corner. to my surprize when i was changing my alternator stranded in the kragen parking lot 300 miles from home i noticed when i was putting my serp belt back on that my fan had been lightly grazzing my radiator shroud. it has to have a tolerance of id say 1/32 of an inch before hitting it again. it only rubs along a 4 inch section in the top driver side of the shroud. i know with most vehicles that the shroud is a little closer on the driver side due to motor lift on acceleration but are these supposed to be THAT close??? That got me looking at a few areas. One was the motor mounts. I noticed that the rubber pads the motor rests on that they were shiffted a little more to the driver side, but it looks like there are detents in the metal protion of the mount that the rubber is supposed to rest in, plus when i start the motor and rev it, the motor does not move much at all. I have looked in the front suspension and besides the normal wear of the control arm bushings, i cannot find one loose component. motor mounts, suspension, body mounts, exhaust, spring bushings, loose bolts, nothing. The last place i checked was the tranny mount. Now the mount appears to be tight but I was only lifting the tailshaft of the t-case with my arms, no floor jack. I suppose the only way that fan could be hitting would be that mount though. if the mount in the rear sags, the metal tabs in the pad touch where it attaches the the cross member, giving me that clunking noise and if the rear is resting lower, then the front would be tilted up, giving me that fan issue. Does this sound right to anybody? Has anyone else had this sissue? thanks for reading everyone.

ak diesel drive
12-31-2009, 02:55 PM
Step on the brake and then give it some throttle while in gear. Probably need a helper so you can watch the mount while doing this. Just revving the engine won't move it enough to see condition of motor mounts.

chevota20
12-31-2009, 03:45 PM
I did do that. I am not able to get down there and look at the mounts themselves, but I popped the hood, applied the brake and gave it some gas. it lifted a little bit, but nothing that I think would suggest a bad mount. Maybe I could use a buddy to help though....Dont trust the lady to do it I gotta lay on the ground with her foot on the pedal?! No thanks

chevota20
12-31-2009, 11:39 PM
motor mounts look fine and so does the trans mount.....body mounts maybe? bad shock bushing?

bk95td
01-01-2010, 11:00 AM
Sway bar bushings or end links?