i am running a 99 expy eb with the 4r70w tranny at 134k. this past weekend on the way to the races I made my own pitstop. when I started the truck again the transmission felt as if it were "slipping" like a worn clutch. It made a strange noise (like leaves in a fan) which I first thought was the serpentine belt slipping so I stopped to check that. After looking things over I drove on and it would "slip" until it shifted into overdrive in each gear. I was less than a mile from the track. I switched off the overdrive and had the slip and noise. switched it off and once in overdrive it behaved and sounded normally. after parked for the weekend the problem has not happened again yet.

I am running mobil 1 atf with the additive for the two years I have owned it. about time to change again. any thoughts?

Pat
austin
99 eb 134k

 

2 years, how many miles? Won't hurt to change filter and fluid.

 

that's what I am figuring for a start. probably 40k on it.