Transmission Service ?'s

[mhawk]

I have been doing some research on what all is involved in the tranny service and I keep coming across some conflicting info on whether or not to flush the transmission. Some say that it can cause more harm than good and others saying that if you are up to date on service it wont be a problem. Can anyone please enlighten me?

 

Thanks

[RWC5S2]

I would highly suggest you "DO NOT FLUSH" the transmission. The only way to properly change it out is to drop the pan, clean the filter and replace the oil. A flush will not clean any debris nor will it get the fluid in the torque converter. It is a slight pain but doing a proper cleaning/draining/replacing every 35,000 miles will keep the tranny running and working for a very long time.

[nissandoms47]

Uh a flush is the proper way, it gets all of the fluid out and replaces it with new fluid, even in the torque converter.. It should get most of debris out unless theres big chunks of it, which there shouldnt be in the first place. Yeah you can remove and replace the filter, but theres no point to doing that. How do you think the fluid in the torque converter gets cooled? It cycles through the transmission through the cooler lines, which is where you hook up the machine to flush it.

[88pathoffroad]

I'd tend to agree if the flush in question is a "power-fill" type machine like the type I used to use at Jiffy Lube years ago. A tank full of fresh fluid either gravity feeds or is pressure-fed/pumped into one cooler line while an empty tank on the machine fills with the old fluid from the other line. Works very well to change all the fluids. You could even watch the machine and see when clean fluid started coming back into the catch tank, that way you wouldn't waste fluid unnecessarily.

[nissandoms47]

yep thats how i did mine, i did it right after i put in my new trans and used a different TC. I could tell when the TC fluid was coming out lol.

[98ChilkootTrail]

Flushing a transmission can help or hurt it. I work in a transmission shop if it has has regular fluid changes or not to many miles on transmission) it usually won't hurt it. but if you have lots of miles and the fluid is getting dark flushing tends to wash out most of the gunk and deposit it in places you don't want (ie. the valve body.) , then your into a overhaul. At my shop we won't service or flush a transmission if it hasn't be serviced regularly or unless it's a newer car.

[mhawk]

Some Background Info:

 

2003 Pathfinder SE 4x4, bought it used in September, it now has 37K miles, and I don't know if it has been serviced or not. I am also planning on adding a transmission cooler (It gets hot here in Texas).

 

Also, the maint. section of the service manual only says to inspect the AT fluid every 15K, nowhere in the maint. section or the auto trans section does it say anything about flushing the transmission. The only mention about flushing anything is flushing the ATF cooler if foreign materials are found in the pan.

Edited March 27, 2007 by mhawk

[Trancebear]

I also have a 2003 SE 4x4 and I have been searching for the interval for changing the tranny fluid, does anybody this? I have 49k miles and I want to keep on top of this. I am in Denver and do a lot of mountain driving.

[nissandoms47]

I think its every 15-20k miles. I would do it once a year unless you're in the car every day.

[navygz19]

I thought it was a little more than that.

If you wheel it, sink it a lot in water/muck/etc., live in the mtns. and drive the snot out of it, change it more often than if you didn't. Just a general rule of thumb. Nothing wrong with being safe