Tranny slipping, advice needed

[jfnar]

I have an '05 2500HD that I used mostly for a hunting truck so it's not driven every day. Recently I've noticed that when it sits for a week without being driven the transmission will not pull for 5 to 10 seconds. After it gets started it's fine as long as it's being driven every couple of days but if it sits for a week it does the same thing all over again. I haven't had time to take it to a mechanic yet but I'd like some idea what's wrong before I do. Any information will be appreciated.

Jeff

[BR3W CITY]

Check your fluid level, and see if its actually all still trans fluid. If the truck sits a ton, you might have water that made its way into the trans fluid, which will change its viscosity and may not build pressure. Same goes if your low on fluid, it'll take a bit to build pressure in the front pump.

[68Gold/white]

I work on medium duty trucks. The older ones (mostly) sometimes do the same thing when started up cold. It takes a few seconds for the transmission to take hold.

My assumption is that sometimes the torque converter may leak down. If you start one of these trucks up, leave the trans in neutral for about 15 seconds and idle the engine up to say, 750-800 PRM's, it will take right off, having NO other issues.

I don't have to drive them very often. When I find one doing this, sometimes I leave the trans in gear and gently push down on the throttle 3-4 times, waiting a couple seconds between pushes.
It will hesitate to move the first couple of pushed, and on the 3rd move a little more, then on 4th or 5th push, move normally.

I have not experienced this on any car or pickups though.........something to think about.

As BR3 mentioned, check your fluid.

Has the fluid been changed lately???