2001 2wd 4.0L transmission disengages under no load...down hill...off gas, etc. I feel or hear it re-engage once rpm drops. 318k miles. Any ideas?
fluid fine

 

Welcome to the forum

Assume automatic trans., so it would be a 5R55E 5-speed automatic

OD is on?
What if you turn OD off before taking foot off the gas pedal

Automatics often freewheel when coasting, until RPMs drop, so I assume this is something new, and it didn't do this last week?

 

I don't have any OD switch and no OD light. Bare bones work truck with nothing power. This is new problem starting a few weeks ago. It so weird that it doesn't come out of freewheeling right away. I have to be careful that I don't step on it...over rev the engine and have it bang into gear. Mech won't do fluid and filter change...said it will cause problems being so many miles.

 

LMAO...it does have OD switch...no markings so I never noticed the button. OK

I took out of OD and let off of gas down hill. Rpm increases as soon as I took out of OD but no slip. Drove without OD...rpm noticeably higher when shifting but no slip.

So it's an OD problem? Or am I just stupid and shouldn't have been in OD all the time...thks

 

You can leave OD on, I just wanted to see if it was part of coasting issue you reported, seems like it is

You have a 5-speed so 4th is 1:1 ratio, 1:1 means engine RPMs and Drive shaft RPMs are equal in 4th
5th is OD which is .75:1 so engine RPMs are lower than drive shaft RPMs by 25%, which gives better MPG but..........no "power", engine has 25% less leverage than in 4th gear
I think OD in this trans is probably .78:1 but same difference, lol.

Not sure why being in OD would cause disconnect, OD is a separate part unlike 1st, 2nd, 3rd and 4th which use the same "gear"
In this transmission 1st and OD are used at the same time to make "2nd gear"
You could put trans in 2 and then see if it disconnects when coasting.


As far as OD driving, if pulling a trailer or carrying a heaver load turn OD off, if driving up a longer grade turn OD off, the computer should do this automatically as engine load increases but it doesn't always do it as soon as it should, and running in OD with higher engine load heats up engine AND transmission fluid, which is a bad thing