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Lhutter1 12-15-2012 06:38 AM

04 WJ trans, flush or not to flush?
Hey guys!

I actually posted this on another thread, but I think this one's more appropriate...

I'm wanting to change out my trans fluid and filter on my '04 WJ (4.7 VIN "N", Quadratrak II) I've read in a few places that it could be harmful to "flush" the trans and to just drain the fluid and refill. Is this true? If so, why?


Trav1s 12-15-2012 06:59 AM

Re: 04 WJ trans, flush or not to flush?
On older vehicles I am all about the drain and fill. I don't like the flush because I know of too many vehicles where the trans took a permanent vacation after the flush. The flush knocks dirt loose and puts additonal pressure on aged seals. Just a bad choice in my opinion.

In November, I did a fluid and filter change the old school way by dropping the pan. To make my life easier I installed an oversized PML pan with drain plug.

jeepmanjim 12-15-2012 07:42 AM

Re: 04 WJ trans, flush or not to flush?
How many miles bro? I changed mine at 70 and again at 140. New filter too. I just disconnected the return line up by the cooler and stuck it into a bucket. Piece o cake. I love my WJ!!! Have the 4.0 though, not 4.7. It's a tiny bit different but not much.

Frango100 12-15-2012 11:35 AM

Re: 04 WJ trans, flush or not to flush?
The good thing of a flush is that it removes all old fluid, and with a simple pan removal you only change 7 litres from the 13 total. (on a 5-45RFE)
I heard bad stories about flushing, because it seems that they not always use fresh fluid in the flush machine, but i donīt know what kind of flush machines they use..
Also not sure if the flush itself would loosen up dirt, because where the fluid goes via the flush, it also goes in normal operation and the pressure should also not be higher then the normal operating pressure. Fresh fluid however has strong cleaning abilities, and could remove dirt particles and take them to places you donīt like them to be, but that would also happen when you just change the fluid.
The secret is to keep the normal servicing intervals, to prevent the dirt to build up in the first place.
I wonder if the trannies which gave problems after a flush, where not overdue for the service to start with.

Lhutter1 12-15-2012 11:37 AM

Re: 04 WJ trans, flush or not to flush?
It's got just a shade over 84 on it. I typically do a fluid change and filter whenever I get a used car, just so I know when it's been done. Seems to shift fine and whatnot, a little sticky now and again once in a while, but I'm hoping that's just the old fluid getting gooey in the solenoids and will improve with fluid change.


Tanner505 12-16-2012 01:29 AM

Re: 04 WJ trans, flush or not to flush?
if you plan on doing it yourself i used the seafoam trans tune on my last trans oil change mainly because i put royal purple in and a transgo hd 2 shift kit and it helped clean all the old varnish and trans fluid out but its up to you

NYU315 12-20-2012 05:35 PM

Re: 04 WJ trans, flush or not to flush?
I'd do the flush ive had a few WJs and never had any problems after,if you can get the TC freshend up as well.

hoffmanestates 12-20-2012 08:33 PM

Wise to do a oil change/filters on 145k?

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AMSOIL_Dealer 12-31-2012 07:07 PM

Re: 04 WJ trans, flush or not to flush?
If you are adding a flushing solution/product the entire amount of trans fluid should be removed including torque converter and lines/cooler. If not a good amount of it will remain with the new fluid. I believe those type of products even recommend a complete removal of the old fluid. ^ 145k with no oil/filter change?? Way overdue I'd say.

hoffmanestates 01-01-2013 03:19 PM

Yeah. But i am 3 owner as far as i know. And old owl mechanics say if you haven't performed it then don't.

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AMSOIL_Dealer 01-03-2013 08:38 PM

Re: 04 WJ trans, flush or not to flush?
How does the fluid look/smell? I know I have heard that as well but, the other side of the coin is sooner or later you will need to do it. Maybe change it/filter run for a shorter duration and change again to remove anything loosened up with the fresh fluid.

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