I'm a newbie to the forums but have had my duramax for 6 years. This is the first problem I couldn't solve by reading these forums, so here's my attempt to add some new info to the wealth of knowledge here.
After my mechanic did a tranny flush he put in some synthetic fluid from auto zone along with the Lucas Fix additive. Immediately it began to clunk at stop and start most of the time. The harder I stop and start, the harder it clunks. After scolding my mechanic who I thought was going to put in Transynd and not use Lucas, since he too drives a dmax, he flushed it again using 3 gallons of transynd. He flushed it by allowing the fluid to pump out of the pump exit hose 4 quarts at a time then adding 4 more quarts down the dipstick tube. After 3 of these cycles using up all 3 gallons of transynd, I feel like the clunk is slightly less, but hasn't gone away. I've put about 200 miles on since and it hasn't gotten better or worse, but I'm obviously driving it like a grandpa at starts and stops. Any ideas for me besides doing my own tranny flush like I did the first time?
After my mechanic did a tranny flush he put in some synthetic fluid from auto zone along with the Lucas Fix additive. Immediately it began to clunk at stop and start most of the time. The harder I stop and start, the harder it clunks. After scolding my mechanic who I thought was going to put in Transynd and not use Lucas, since he too drives a dmax, he flushed it again using 3 gallons of transynd. He flushed it by allowing the fluid to pump out of the pump exit hose 4 quarts at a time then adding 4 more quarts down the dipstick tube. After 3 of these cycles using up all 3 gallons of transynd, I feel like the clunk is slightly less, but hasn't gone away. I've put about 200 miles on since and it hasn't gotten better or worse, but I'm obviously driving it like a grandpa at starts and stops. Any ideas for me besides doing my own tranny flush like I did the first time?
