4L80E Odd Fluid Level Issue

[rustyk]

I checked the fluid with the engine off, and it's barely on the dipstick (at the right level for hot - when I measured); running in "Park", the dipstick tube is half-full of fluid. I have the Mag-Hytec pan, so there's plenty of fluid (I think). Temps appear to be normal (~180°), but slightly warmer than I'm used to - but ambient temps are higher, too. The transmission operates normally.

Any ideas?

[Robyn]

Always check in Neutral. The flow though the tranny is not the same in Park.

As long as the level is correct in Neutral Hot your Good to go.

Missy

[WhiteTruck]

Fluid level can be checked in neutral, but I don't recommend it for safety reasons. Fluid level will be the same in park or neutral. There is no difference in the fluid flow on a 4L80 trans between these 2 ranges, only the engagement of the parking pawl, if equipped. I know you don't have a park pawl on your version. Robin is likely thinking of a big rig trans, I have no idea of fluid flow on them.

[rustyk]

On another forum, I got more info - mostly echoing my experience with the dipstick tube. One retired GM engineer griped about the same issue...and both posters agreed on an odd but apparently useful work-around.

The thread is here (http://barthmobile.com/eve/forums/a/tpc/f/3631087061/m/391105282)

[rustyk]

One of the techs here at Sun Coast/Webb's Transmissions discovered that the tranny vent tube was pinched, likely causing the problem.