Transmission Flush?

[CowboyDren]

First off, I'm used to SMALL cars, with SMALL gas tanks and SMALL fluid reservoirs. The '98 Grand is more than a bit of a change for me. A friend of mine works at a good service station with good equipment, and they do good work. But they want $180 + shop supplies to do a BG low-pressure trans flush.

I had planned on doing a driveway filter change and flush: I drop the pan, change the filter, replace pan, refill lost fluid. Disconnect trans cooler supply line, run it into a bucket. Start the engine, and as the line dumps into the bucket, replace fluid via the dipstick tube. The high volume from the supply line freaks me out a little, but I'm determined.

Then I read this page, which says that a total refill on a 42RE takes TWELVE POINT FOUR QUARTS of fluid that cost $6.29 per bottle. WTF? Is this correct? The friggin' Jeep owner's manual just says "take it to a Chrysler service center," and I don't have a DIY manual yet, so I'm stuck relying on whatever **** I read on the internet.

Side note; I like Haynes manuals, my wife likes Chilton. Is there a good reason to pick one over the other for this Jeep? Not looking for an FSM just yet, unless you want to let one go for under $25. ;)

[ericfx1984]

I thought you could use regular atf... more like $2-3 per bottle... you should research it but I think you can if you just change it all out and flush it really well

[WesSaun]

my 96 grand used dextron 2 or 3 I forget which, or mopar atf+3.
walmart carries atf+4 much cheaper than the parts store.

when i flushed mine it took 6 quarts give or take, by dropping the pan and blowing the lines in the radiator. your not going to empty the torque converter which holds 4-6 quarts, and running the system and letting the TC or pump run dry is not good for the trans.

a power flush by pouring in fluid as the pump sends it out will take alot more fluid, but will get the old fluid and debris out of the torque converter and radiator better.

from what i hear though doing a power flush can lead to transmission failure due to debris being stirred up and causing problems. I know several people that have had to replace/rebuild a trans within months of a power flush, but I do not have any personal experience with it.

[rjh]

I've heard to just change it, put it back together, change it again, etc. lather, rinse, repeat. You know the old saying... "The solution to pollution is dillution."

[cwaage]

Look for the Haynes on eBay - they published on that was 1993-1998, then they revised and added the 1999-2003. I looked at the 1993-2003 version, and it seemed over-complicated because it was covering two body styles.

My copy was $10 plus shipping on eBay.

Oh, and in my opinion, other than the true Chilton's "Shop Manuals" (the big, expensive books), the consumer edition of the Chilton's are pretty much useless.

[reward_1000]

According to the computer at the shop it does take ATF+4, so the fluid will cost more. How many miles are on the jeep? Has the fluid ever been flushed before or changed at least? Why are you wanting to change it? If it had over 120k and has not been changed before and the fluid is fairly dark do not flush it. If it is clean and the transmission is working correctly then a flush is a good service to perform. I reccomend a flush over a filter service any day of the week, it is the only way to guarntee full fluid replacement. These are the guidlines I use at the shop on a daily basis. One thing to remember though is that if the transmission is not shifting correctly pulling the pan is a must to see what you have in it.

[93WHY-J]

According to the computer at the shop it does take ATF+4, so the fluid will cost more. How many miles are on the jeep? Has the fluid ever been flushed before or changed at least? Why are you wanting to change it? If it had over 120k and has not been changed before and the fluid is fairly dark do not flush it. If it is clean and the transmission is working correctly then a flush is a good service to perform. I reccomend a flush over a filter service any day of the week, it is the only way to guarntee full fluid replacement. These are the guidlines I use at the shop on a daily basis. One thing to remember though is that if the transmission is not shifting correctly pulling the pan is a must to see what you have in it.

This is good advice. I will add my opinion...if the fluid has not been changed on a regular basis (every 30,000 or so) I would recommend NOT doing it now. It will most likely cause more problems than help. Auto transmissions are a touchy creature and don't like change much. If it is working correctly, I would say leave it alone.

[CowboyDren]

I thought you could use regular atf... more like $2-3 per bottle...

I'd NEVER put anything less than ATF+3 in ANY Chrysler transmission. I'm not telling you what to do, just sharing what I've learned. The performance of +3 versus DexIII isn't much, but +3 is still better. The performance difference between +4 and +3 is significant, especially at 30,000 miles of age. My Jeep specifies +4, but I can't find how many quarts.

walmart carries atf+4 much cheaper than the parts store.

...a power flush by pouring in fluid as the pump sends it out will take alot more fluid, but will get the old fluid and debris out of the torque converter and radiator better.

...from what i hear though doing a power flush can lead to transmission failure due to debris being stirred up and causing problems.

1 - It never occurs to me to check Walmart. Thanks for that.
2 - Nobody said anything about running it dry, your second paragraph is what I'm saying, which is a low-pressure flush.
3 - What causes failure are high-pressure flushing systems that force fluid into the case faster than the pump can evacuate the pan, which stirs debris, which causes catastrophic failures.

I've been down the high-pressure road before in a '78 Silverado. Fortunately, a vacuum-operated TH350 was about $200 when I learned that lesson. A 42re isn't a $200 transmission.

Look for the Haynes on eBay - they published on that was 1993-1998, then they revised and added the 1999-2003. I looked at the 1993-2003 version, and it seemed over-complicated because it was covering two body styles.

The ZJ-only edition is the one I'm eyeballing. I've found two used copies in "acceptable" condition for $7+s/h. Thanks for the pointers.

According to the computer at the shop it does take ATF+4, so the fluid will cost more. How many miles are on the jeep? Has the fluid ever been flushed before or changed at least? Why are you wanting to change it?

...I reccomend a flush over a filter service any day of the week, it is the only way to guarntee full fluid replacement. These are the guidlines I use at the shop on a daily basis. One thing to remember though is that if the transmission is not shifting correctly pulling the pan is a must to see what you have in it.

Thank you SO MUCH for chiming in. Does that fancy computer-machine tell you how much fluid I'm supposed to put into an empty transmission, if that was what I were trying to do?

Chassis has 173,000 miles. Transmission is "3-4 years old," according to the previous owner. Assuming that her power commuting from school in KC to home in Des Moines put two-thirds of those miles on in half of the chassis' life, it could be 50,000 miles old. Also, according to "Julie," the transmission was "looked at" by a shop in Olathe about a year ago, but "Julie" didn't say why or what was done. Let's assume that the fluid is only a year old, which the bright cherry color and nearly-new clarity verify. My problem is that there's a whiff of scorch on the dipstick, but just a whiff. I've also had trouble with the 1-2 shift at light throttle being delayed to the point that I consciously wonder if it will ever start to shift, but only at light throttle.

My plan is to do some over-the-counter pre-flush additive for a few hours, or a few minutes, whatever the can says. Then drop the pan to inspect it myself, replace the filter and gasket, and hope I don't find two pounds of band/clutch material just laying there. I will then proceed with the pump'n'dump with +4. This mimics the BG process, but is more thorough, because I am doing the filter and taking the time to look for sludge. If it doesn't straighten up, I'll take it to Raytown Transmission for a band adjustment and solenoid replacement. $300 now sounds a helluvalot better than $3000 in six months.

I think 12q of +4 is excessive. I think that 8q is a lot more reasonable, unless somebody can tell me otherwise. So...how much do I really need?

[ericfx1984]

I'd NEVER put anything less than ATF+3 in ANY Chrysler transmission. I'm not telling you what to do, just sharing what I've learned. The performance of +3 versus DexIII isn't much, but +3 is still better. The performance difference between +4 and +3 is significant, especially at 30,000 miles of age. My Jeep specifies +4, but I can't find how many quarts.

good to know, thanks for the heads up

[rjh]

I think 12q of +4 is excessive. I think that 8q is a lot more reasonable, unless somebody can tell me otherwise. So...how much do I really need?

If it was me, I'd buy 14 quarts, and take back whatever I don't use (that's unopened). I hate making multiple trips in the middle of a job. :)

[reward_1000]

I agree with Rich. I use 22 quarts when I drop the pan fill and flush. The amount required to fill the transmission after dropping the pan will vary from 4 to 8 quarts. If you drop it when the fluid is hot you will not need to put in as much. If you drop it when the fluid is cold then you will need more. This is due to the torque converter draining. Also remember to check the fluid in neutral.

[spunebil]

unless ya drained tranny and torque convertor.....you wont need that much (torque convertor holds like half if not more of fluid)


at least they did last time I messed with them ! ;-)

[CowboyDren]

After much waffling and gnashing of teeth, I've decided that the best plan of action is to run some Seafoam Trans-Tune, watch for color change, and if it's not drastic, I'll do the filter and gasket myself, cold trans, and call it good. If it is drastic, I'll just have the shop do a flush after I do the filter. Bah. Thanks for all of the input, guys.