My 01 bolt has just passed the 30.000 mark. Its time to change the fluid in the transmission. I did put the line mod valve and 4x4 tranny pan about 12000 miles ago, so I did put 8 quarts of brand new fluid back then. Anyway, the dealer said that there are two type of services:

1) They drain the old fluid out, flush the tranny and refill it with new fluid, but they leave the transmission pan on and leave the existing filter.

2) They remove the tranny pan, change the filter and refill with new fluid.

Which is a better choice? I don't think that they flush the tranny in option #2.

PS: I did put a new tranny filter along with the 4x4 tranny pan about 12000 miles ago. Please give me your opinions.

 

Watch those flush machines. They may back wash all the stuff the filter traped back into the tranny. Best to change the filter before the flush.

Just my $.02
Jace

 

That's not right. There is no way to "backflush" a tranny, they only pump oil in one direction, I guess you could put a wrench on the crankshaft and turn the motor backwards, but I'm not even sure that would work. A flush machine simply pumps the old fluid out while putting new fluid in. And that's all you need. My rule on filters is, if you have a reason to drop the pan, change it, but just changing the fluid in not a good enough reason to drop the pan. The filter in the transmission is not on the maintenance schedule, officially you never need to change it. After the first 100 miles there is very little to get trapped in the filter unless you have damage to the transmission, but on a routine fluid change I'd not bother with the filter, especailly if you already changed it once.

G

 

Hey G (its Greg right?)

i was wondering what you opinion on the flush machine in general was? It seems to me that using that method involves alot of mixing of the old and new fluid so your really not gettin all the old fluid out, granted your still gonna have some fluid left in the lines even if you drain the pan and the converter but when i did mine i barely missed the fill by less than half a quart or so. I normally just do it myself, but its really not one of my more favorite jobs (tranny fluid in the hair is a pain to get out, espcially the smell) so how effective is that thing?

 

I thought those new 4X4 pans had a drain Plug?
Sounds like your not real comfortable with that machine mixing your stuff, not to mention what ever else has gone threw it.

You would sleep better if you did it yourself and changed the filter. It isn't a fun job but it doesn't have to be done that often.
Greg

 

brasil,
You might have a drain plug on the torque converter on your "01. If so I would drop the pan, change the filter and drain the TC. It took 13.5 qts to refill mine. You won't remove even half the fluid by just dropping the pan!
The only minor problem is to get the TC drain plug to the bottom. Best done with 2 people, one bumping the starter and one watching for the plug to stop at the bottom. When the plug is close to centering on the bell housing hole you can take a large screwdriver and turn the flywheel to center it up.
I think the flush machines are OK and remove most of the old fluid but it's hard to imagine that it will completely flush out all that's in the TC.
DW

Also, if you drain the TC, you will need to refill by adding about 6 qts and then run the engine for about 30 sec to pump the fluid into the TC. Then add about 3 more qts, start the engine and add the rest while it's running. YOU CANNOT POUR IN 13.5 QTS WITHOUT RUNNING THE ENGINE TO PUMP THE FLUID THROUGH THE TRANNY AND TC! Well actually you can, but the huge mess would not be pleasant.

 

I do have the drain plug, since I upgraded to the 4x4 pan.

Factory tech, so you don't recommend draining the pan an changing the filter? Is it better just to hook up the machine with the BG cleaner without dropping the pan?

 

Anyone else?

 

i believe his recommendation was if your gonna drop the pan change the filter, but changing the filter is no reason to drop the pan. Hence, the machine flush should be fine.

 

Teh machine flush is the best way to get all the old fluid out. It doesn't mix it very much at all, it goes in tot he tranny at the rear lube, falls into the pan, get sucked up to the wormtrail and converter and goes out to the machine, where it is kpet isolated from the new fluid, it's the only way to get the fluid from the clutch packs. If they let you, it would be even better if you cycled through the gear selector while you did it, to get the wormtrail completely purged.

G