2002 silverado with 6 liter. slips going into 3, and when going down hills or bridge it comes out of overdrive. it takes 1 to 2 miles before it goes back into overdrive. what could it be?

 

Are you throwing any codes?

 

could be as simple as a clogged filter or low fluid level. could be as complicated as needing a new trans. how many miles and what mods do you have on the truck?

 

If it's a 6.0L in front of a 4L60-E it must be an engine swap. Assuming that is true there must have been some tuning involved. Depending on whether the original engine was a 4.8 or a 5.3, line pressures will have needed to be increased across the entire RPM range in all gears for the greater torque of the LQ4. Unfortunately, all it takes is one bad slip of the 3-4 clutch pack where it gets hot and you end up with permanently warped steels. Get the tuning in order and then get ready for a rebuild. A 4L60-E needs upgrades anyway to live behind even a stock 6.0L.

 

Motor was tuned, headers, exhaust, convertor and trans cooler. Did not tune the trans after the swap.

 

No codes

 

Might be a checkball in the valve body the one thats in the top and sorta to the middle of the plate..that one always makes a bigger hole threw the valve body plate.. And makes it go in and out of 3 gear

 

My 60e slipped going into 2nd, i programmed it and upped the shift points by 300 rpms and it made a difference, doesn't slip anymore so we'll see how long it lasts now.