Auto transmission

[Larv]

I have what is a silly question to some but I'll ask anyway. Does the ATF operating temp determine when the transmission shifts into OD? It seems to take quite a bit longer in the winter. Also, I let the truck idle for 1-2 mins in the morning (in neutral) as I've been told no transmission fluid is circulated in park. Am I correct? Thanks for any input!! Larv

 

[Joe G.]

The ATF must be warmed up some before the computer will let it shift in to OD. It will warm up better it you just drive it easy. Idle doesn't generate enuff heat to do anything, especially in park.

 

[Snow man]

My 96went,and my 2000 goes right into OD. no delay or anything,the lockup doesnt come in as fast,but they go right in.

 

[Steve Roseman]

Larv, Not a silly question at all. If I don't warm my truck up before leaving, it won't shift into OD for about a mile sometimes. It all depends on the outside temp, I'm sure you're experiencing some low ones right now

 

[Cooker]

I think the magic number is 80 degrees. The transmission won't go into OD until the fluid reaches this temp.

 

[GDouglas]

You won't accomplish mush fluid warming in park at all because there is no cooler flow at all in park. Along with no cooler flow comes no converter fill/charge. Why does DC do this? They have designed their trans for years like this for some stupid reason. If you look at the owners manual and on most of the trans dipsticks, you will find a note to check fluid level in neutral, not park because of this.



Good news is that most good aftermarket shift correction packages and valve bodies have some sort of modification made to get converter charge and cooler flow in park.



As for a delayed lockup and/or 4thwhen cold, the PCM looks at quite a bit of info to determine when to give it to you. Trans fluid temp, engine coolant temp, and calculated loadare all taken into account to determine when it will give you lockup and 4th. Hell, if DC PCM programming is anything like Ford's, then there may be a lot of different calibrations floating around in different trucks all across the nation.

 

[Larv]

Hey, thanks for all the good replies! On cold mornings I let it idle for 2-3 mins in neutral thinking it might shift smoother as the first shift seems a little herky-jerky. Then the OD doesn't shift for quite awhile but the ATF temp (or lack of) explains that. My engine oil temp gauge doesn't move ever. Dlr thinks it could be a sensor or thermostat. We'll know Wed. Larv

 

[Dr.Kayak]

Once, while checking for leaks after installing a new transmission cooler line, I let mine idle in drive with the parking break set. Within a few minutes my transmission temp. gauge was up to 180.



I would say this is a very fast way to warm up the transmission, But I doubt it is very safe to leave the truck unatended in drive.