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03-25-2011, 10:13 PM #1
- Join Date
- Mar 2011
HARD shift after driving for 30 minutes
I have a 99 GMC Suburban LS 4x4, auto trans. I just bought this truck and previuos owner had it sitting for 5 months. I have put 500 miles on the truck.
It shifts smooth as silk when running 20 minutes or less. If I run it longer, I get very HARD shift on 1st and a medium HARD shift on 2nd. Truck has 173k miles.
Trans fluid looks good and does not have a burned smell.
What steps should I take to resolve. Do the Trans coolers go bad and need to be replaced? Do I need to get a trans flush ? Do I ndeed a repair?
Any help would be apprecaited.
03-26-2011, 02:22 AM #2
- Join Date
- Feb 2011
- Locust Grove, Georgia, United States
your valves in the valve body are getting hot and sticking1999 GMC Serria
Regular cab short bed
4.8 Vortec (6.0 swap soon)
Custom cold air intake and spacer
Bullydog GT programmer
Flowmasters with turndowns
55w 12000k Hids highs and lows with low and high relay
Viper Remote start
200 psi Train horns and onboard air
285 Courser M/ts
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