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Flushing the Transmission Fluid (myth or fact)

 
I just bought a 2000 XJ with 168.000 miles on the auto trany. The trany fluid appears to never have been changed. The fluid is dark brown and looks more like used motor oil. In my case scenario (especially with high mileage), I was told that flushing my transmission system is probably a bad idea and could lead up to problems. Supposedly the flushing process puts more pressure through the lines which could break loose normal build up. The forced pressure not only dislodges build-up, but it uncovers hidden leaks. The end result could lead to premature transmission failure. So, instead of flushing, I was advised to change the transmission fluid by simply draining the pan and adding a little each time until the system is fairly clean. Is this a Myth or Fact?
 
I do a drain plug oil change run it for awhile (2-3 months), change it again, then run it for awhile, change it again and then change it yearly. Unless there are issues, then I change it three times in a week.
Reason being, if there is any/much varnish buildup in the odd corner or crevice, I want it to move gradually (if at all). If too big a chunk of whatever breaks loose it is bound to cause issues.
Just an opinion that's worked well for me so far. I've had one tranny pan off for a cleaning (about 16-17 years ago), had a look and decided it was a waste of time and have never opened an AW4 again unless it was broken.
 
I agree with the previous poster however I did have a Dealer do a tranny flush at 50K but would not advise one with your mileage given the poor maintenance.
IOW, no on the tranny flush
the drain and fill method should be fine
 
I think the flush causing failures perception is a myth. Lots of people don't service their trans or it just wears out and when it starts to have internal issues, decide to flush it. Of course the failure continues on its merry way, but now it's because it was serviced.

The BG machine I use is powered by the transmission's front pump, not air or electricity. It does not generate higher pressures than what the trans sees every day.

A flush doesn't clean the filter, of course. Never a bad idea to drop the pan and see how the internals are doing by assessing how much friction material and wear metals have made it to the bottom. Yes, it's technically a screen- clean it if you want, I replace them like any other filter.

That only does about 1/3 of the total fluid volume. A cheap home flush can then be done by routing the cooler return line into a drain pan while keeping the trans filled, flush until new colored fluid comes out.
 
I agree that flushing has gotten a bad wrap but that being said, with a tranny with 168k and original fluid, IMHO, I would do multiple drain and fills over a period of time and also clean/replace the filter(screen).

The multiple changes would introduce new fluid and allow for a gradual cleaning of internal parts while allowing any varnish or debris to be drained out over that interval/multiple changes. Be sure to use Dexron III fluid.
 
I think the flush causing failures perception is a myth. Lots of people don't service their trans or it just wears out and when it starts to have internal issues, decide to flush it. Of course the failure continues on its merry way, but now it's because it was serviced.

The BG machine I use is powered by the transmission's front pump, not air or electricity. It does not generate higher pressures than what the trans sees every day.

A flush doesn't clean the filter, of course. Never a bad idea to drop the pan and see how the internals are doing by assessing how much friction material and wear metals have made it to the bottom. Yes, it's technically a screen- clean it if you want, I replace them like any other filter.

That only does about 1/3 of the total fluid volume. A cheap home flush can then be done by routing the cooler return line into a drain pan while keeping the trans filled, flush until new colored fluid comes out.

I agree, people seem to think changing the transmission fluid at all is a bad idea too. I read all the time someone advising against even a drain/refill because the transmission "is used to the old fluid". Again its the same situation, a transmission that's already on its last legs then the fluid is changed. The fluid change doesn't solve the problem and what was going to break does just that. So, people look at the fluid change as the cause.

I would just drain/refill a few times over a period of time until I get clean fluid coming out. That's mostly because I don't want to take my vehicle anywhere to let anyone do work to it :gag: .
 
I drained the trany pan today.............. I'm just thankful the pan has a drain plug. With that being said, how many quarts does the pan actually hold? It looked like I drained out about 2.5 quarts. I think the total capacity is 8.3 quarts.
 
A lot of the fluid stays up in the main transmission housing until the valve body is removed. 3 quarts to start for just a pan/ filter (screen) r/r sounds about right.
 
just a tip
be conservative when re-filling and don't add anymore than you removed.
Drive it for awhile and top it off if necessary.
It's very easy to add too much.
 
i get 3.5 quarts on a drain. when i took the pan down i got 4 quarts.

just for your info after 6 drain and refills it puts you in the 98 percentile of new fluid.
 
I am probably going to do a flush this weekend... 128k on the thing and I don't think the PO flushed it once. I'm pretty sure it'll fail so I may just buy a new transmission first at the JY ($120, amusingly about the same price as a full flush at most quicklubes) as I know I'm gonna blow a transmission at some point.
 
I just did my second transmission drain and fill today. It’s a good feeling to see cleaner fluid appear on the dip stick. I don’t have an owners manual, so I was wondering exactly how to check the fluid level. I’ve been checking the fluid by placing my transmission into neutral and checking the dip stick while the vehicle is at idle. Is this correct?
 
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I am in the same situation. I bought my XJ a little over a month ago and the fluid looked like motor oil. In fact, whenI dropped the drain plug, I thought I dorked out and dropped the oil pan plug- the fluid was that bad.

I asked a tech about doing a flush and he advised against it for similar reasons above.

I am in the process of doing the repeated drain and fill, and the fluid is looking better, and tranny performance feels a lot better.

When I am done (it appears 6 times according to x99j) I will replace the filter.

EDIT: I have 147k miles
 
You can also disconnect a cooler line and run the jeep for a few seconds. Fill up the pan, start it up again.... Keep repeating till it starts coming out red. Took me about 2 gallons. Between that and a new filter, my once crappy feeling 170k AW4 now shifts great.

Mine came out pure black and smelled pretty bad
 
i wouldn't flush it that that many miles, and old oil.

i ran into the same problem with my cherokee. to get the fluid back to pink though i drained the tranny (about 4 qts) and drove it for a week, and repeated 2 more times. by the 3rd time my oil has stayed pink.

the way i see it, it did cost me an extra 4 qts of tranny fluid, but seemed like a safer way of doing it
 
i wouldn't flush it that that many miles, and old oil.

i ran into the same problem with my cherokee. to get the fluid back to pink though i drained the tranny (about 4 qts) and drove it for a week, and repeated 2 more times. by the 3rd time my oil has stayed pink.
new transmission fluid should be deep red, not pink.
what type/brand of fluid did you buy?
 
my once crappy feeling 170k AW4 now shifts great.

Last night I completed my second drain and fill with Amsoil ATF. It’s hard to believe, but my overdrive is now working!!!!!!!!!!!!!!!!! When I bought the Jeep last week the overdrive didn’t work. I was told that changing the transmission fluid might help. Sure enough, it worked! :guitar:
 
That Amsoil ATF is awesome....
 
One thing everyone may want to watch is , I believe, that tranny fluid level should be checked hot, as in driven a few miles, engine up to temp. The stuff does expand, making it even easier to overfill. That's why most tranny dipsticks are marked HOT and COLD.
Also, starting in '96, the fatter exhaust pipe crossing under the tranny makes it difficult to get the pan off. When I first got the '96, I ended up loosening the pan and reaching up over into it to remove the filter, allowing me to finish removing the pan. So for the forseeable future, it's drain and fill only.
 
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