Another 4L80E Question

[gunner 6165]

95 C2500, diesel, my dad's truck.

When cold, from a dead stop, truck acts like it's in neutral for a second or two, then goes into gear and truck shifts normal in all gears. Once it's up to temperature, problem goes away. The truck is totally stock, it's his farm truck. Not real sure where to start with this, looking for suggestions, hoping someone has had this before.

[rjschoolcraft]

Change the filter, for starters. When was the last time that the fluid was changed?

[DmaxMaverick]

Sounds like torque converter drain-back. Could be caused by many things, and is not uncommon after many miles.

The check for this is easy. On a morning the truck has been sitting long enough for you to expect the condition to be present, check the fluid level before you start, and make a not of it. If the delay happens on that start, then you got a good test check. If the delay doesn't happen, do the check on another cold start at a later time. You need a check on a start the conditions exists. Check it again on a hot tranny, after about an hour of sitting and compare the two. If your converter is draining back, the cold check will be considerably higher.

If your checks are not considerably different, you could have a sticking poppet or solenoid.

Either way, the first remedy is to use some tranny flush fluid (like Trans-X or TransMedic), then a flush/fill. The flush may free up whatever was stuck. Also consider changing to a good synthetic fluid (Mobil, Amsoil, Redline, etc.). They tend to have fewer issues with this problem, and may prevent your problem from resurfacing.

[gunner 6165]

Thanks for the info guys, I don't know when the fluid was changed last, probably a few years ago, maybe 5k miles ago. I'll pass the info along to him and see what happens.