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Tranny fluid flush? Yes or No?

csr_011

NAXJA Forum User
Location
Lincoln, NE
Im talking about the machine that hooks up to your tranny lines and runs fluid through until it is clean.

How many people like the tranny flush thing?

Is it good or bad?

Should the filter be changed first if it hasnt been done in about 40K miles?

Cory
 
The flush works pretty well, friends shop has one of those machines and he did it on his grand opening day on two vehicles, one a 03WJ that belongs to the receptionist at the shop and the other one was his dads Buick. Worked fine and no problems. We had my wifes Oldsmobile done when there was a sticking problem in cold weather, would not go into drive for almost 10 min after warming up. Put a can of sea foam in, ran it for 5 days and brought it back and flushed it. It has been fine ever since [knocking on wood].
 
I have had it flushed twice. I have had no problems. the second time I had it flushed was because I found out later it had the wrong fluid in it. Before I had it done the second time, I called around various shops to see if they did a flush. 2 said yes, 2 said absolutely not.

Now that I know I have the proper fluid in there, I am going to continue simply pulling the plug and refilling the 4 - 5 qts. I may drop the pan every other or so just to check the filter, but that is probably it.

If you do go the flush route, the place I took it to for an extra $20 would replace the filter. Actually seemed reasonable, though I felt it was unnecessary.
 
Just drain the pan a few times - you'll acomplish the same thing an still have an extra ~$100 in your pocket. You can get a case of ATF at Costco for $11....enough for 3 flushes.
 
IF the tranny's in good shape, the flush works fine... :gag:
In a high-mileage Blazer I had, the tranny was starting to slip a little, so I took it in to get a flush done...BIG mistake! I had to replace the tranny the next week. Apparently the machine cleans out the tranny REALLY well, including removing the gunk that was keeping my old tranny shifting at all. :rattle:
YRMV.
 
Well, I do tranny flushes all the time at work. There is a few myths about this service. Or at least with all the machines I've ever used.

The power flush. People assume we are using to machine to "pressure wash" the insided of the tranny. I've never seen a machine that does this. Maybe there is a machine out there like that, but I'd never use it. Doing so would raise the pressure which as you can imagine could lead to serious problems blowing out seals.

Flushing your tranny will not loosen junk and cause more problems. If something like that happens to occur, it was going to happen anyways.

Now what a transmission flush really does. It exchanges the old used fluid in the transmisson for new fluid. With most machines, you tap into a tranny cooler line inline. Then you turn on the car, and let the transmission pump, pump the old fluid out of it's self. While doing this, you must add fluid at the same rate the transmission is pumping it out. Some machines automatically do this. Other machines require an opperator to check the dip stick and adjust the amount of fluid that is being pumped into the transmission.

Personally, I'd stay away from any additive. I've never seen one that is proven. Just make sure you use nice clean fluid. A quailty fluid, rated to your vehicles spec's will do more for it then some cheap bottle of goo.

I would not hesitate to flush the tranny at all. Find a shop that you trust, with the brands of fluid you prefer and have them take care of it.

As for the filter. Normally they don't need to be change that often, if the fluid is regularly maintained. However, if you don't know the vehicles past, or know that it has some nasty fluid in it, I would reccomend doing the filter to. If you flush your system every 30,000 miles, the filter should be last ~90,000 miles. Most places won't tell you anything like that, they are looking out for their profit margins. (Of course there are always exceptions)
 
If you have ever rebuilt an Automatic transmission, you know that is all hydraulic. If you know anything about hydraulic systems, you know that changing dirty fluid out for clean fluid will not damage the system. Gunk in your system, if anything will cause your tranny to malfunction, not make it work better.

If you are having a problem with your transmission, the flush WILL not fix it. Flushing a system is maintence, not a repair.

Compare it to some other common systems on the vehicle. Lets say the braking system. It's hydraulic, it works pretty much identical to the transmission in that reguard. How many people have you heard of that have had their brake fluid changed, and lost their brakes soon there-after? Same goes for the powersteering.

People don't know much about transmissions. You get a lot of people that bring them in only after they start having problems. If everyone treated their engine like their transmission, you'd see people going 50,000 miles on oil, and only bring them in to be serviced when they hear a rod knocking.

I'm a firm believer in scheduled maintance. The more you maintain the vehicle the longer it will last.
 
Yeah, biggest advantage to a flush is getting all the old fluid out. when you drain the pan, you still leave quite a bit of old fluid in the converter. i did a flush on mine, only cause i got it done at cost ($65, including the atf), my jeep had 155,000 on it when i got it. didnt know the history. now that i know it has good fluid, as long as the tranny survives, i'll just drain and chainge whats in the pan. and the shop i worked at actually alternated between flushing and changing the fluid/filter every 30,000 or something.
 
I was just curious, thanks.

I have had it done before in two other vehicles in the past. Both trannys shifted a bit smoother afterwards, but were fine when i went in. I just wanted some input on it.

The Cherokee, im not sure about, the tranny is fine now, was doing some weird stuff off the line a month or so ago, but that quit..?? The tranny is original and has 261k on it. Original, so the previous owner said.....

I think im going to get the flush done with a new filter. The fluid looks a bit darker than it should, but doesnt smell burned. Know a good mechanic around here who isnt afraid of the Jeep reputation......he he.

Oh, I would like to add that this is now my daily driver since my 97 Dakota was totalled in June. I opted to stick with the 87 XJ that I have been slowly rebuilding and save the money from the wreck. Its been a rough road, but I am through the worst part of it now......thank god... Finally got the thing "stable", OR it just likes the cold. A few new parts in the last 6 or 7 months, some new wiring, working on freshening the rest of the drivetrain and fuel management issues. A new fuel tank and all the guts, differentials and tc fluids flushed, tranny flushed, then off to lift kit land.......yeeeehaaaw!

Thanks again.

Cory
 
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A little bit off subject...but I thought I'd add it anyways. I have a good friend who is a Tranny-tech at a fairly big Chrysler/Jeep dealership. I was talking to him about an hour ago and we were talking about my XJ. The amazing thing he told me was this:

He's rebuilt or replaced 728 Chrysler/Jeep Automatic Transmissions.
He's been too several Transmission tech schools through his dealership.
He has NO idea what an AW4 tranny's internals look like...other than from pics or from looking at it from the outside....LOL...he has NEVER had
to rebuild one or tear one down yet!!!

He's replaced TCU's...modulator's or a few other things...but he said they must be pretty kick a$$! I've owned 7 jeeps and have yet to have a single tranny problem yet. (knocking on wood)

I found this to be an amazing....if not somewhat out of the ordinary...Fact.

Just thought I'd tell you guys about it. It makes me feel pretty confident about my tranny!

Aron
 
The AW-4 is pretty stout, mainly due to good lubrication. Which makes Redsand's statement even more accurate. You have to maintain it to keep it going, like any other tranny. If you have really hard shifting or noise it's too late, a flush will be useless. Too many people come into my shop thinking the voodoo box just wants clean fluid to make it new again, they've heard it before & insist on new fluid, & it NEVER works.
 
Look in the owners manual,the service interval is 20,000 miles.Heat is the reason that the fluid breaks down.Most of us wheel and place heavy stress on our trannys.So have it flushed ,add a cooler if necessary its cheap insurance.
The "filter" in the AW4 is just a screen to catch the big chunks.If you don,t know the service life of the vehicle then change it on the first flush you do and then forget about it.
Wayne
 
Yeah the filter is a steel one, so no need to replace it just clean it.

I've flushed mine and put in Redline ATF. I was havign a problem with the regulkar fluid turning slightly brown(not burnt but not red), so my shop flushed it. Unhooked one end of the tranny cooler lines and pumped out the old fluid and poured new in until it ran red. No problems now and it shifts,works fine.
 
redsand187 said:
Compare it to some other common systems on the vehicle. Lets say the braking system. It's hydraulic, it works pretty much identical to the transmission in that reguard. How many people have you heard of that have had their brake fluid changed, and lost their brakes soon there-after? QUOTE]

not to bash u or anything but that does happen frequently, the master cylinder rides in the same spot all the time when you bleed your brakes or blow a line it move much further that usualy. this can cause the seals to go. just like a seal on a shaft that gets a grove your master does the same thing now when you go moving it over that grove it can cause damage. not always but sometimes.
yea this was a little off topic so
change the fluid new is better than old less contaminates also when changing the filter make sure it is in super clean environment tranny's don't take well to dirt use those rags that don't leave lint.
 
If anyone read my other thread about tranny fluid and filter change u'll know i'm having a bit of a problem...(not to hijack) but what fluid are you all changing w/ b/c i was told not to use ATF-3...even though my owners manual and jeep dealership says to...Dextron-3 is what i should be using. I just put 4qts of ATF 3 and changed my filter...should i pay money to have it flushed and put in Dextron III??
 
JeepXJ93 said:
If anyone read my other thread about tranny fluid and filter change u'll know i'm having a bit of a problem...(not to hijack) but what fluid are you all changing w/ b/c i was told not to use ATF-3...even though my owners manual and jeep dealership says to...Dextron-3 is what i should be using. I just put 4qts of ATF 3 and changed my filter...should i pay money to have it flushed and put in Dextron III??

You should use Dex III and ONLY Dex III. Yes you should have it flushed. Worse than using ATF+3 is using only 4 quarts of ATF+3 mixed with Dex III, which is what it sounds like you're doing...
 
The guy who owned it before me always had it serviced at the dealer...so technically if Milford Jeep/Eagle told me to use ATF 3 then shouldnt whatever dealer the previous owner took it to have the same specs? I will find somewhere to get it flushed and supply them w/ dex III. Thanks
 
bj-666 said:
redsand187 said:
Compare it to some other common systems on the vehicle. Lets say the braking system. It's hydraulic, it works pretty much identical to the transmission in that reguard. How many people have you heard of that have had their brake fluid changed, and lost their brakes soon there-after? QUOTE]

not to bash u or anything but that does happen frequently, the master cylinder rides in the same spot all the time when you bleed your brakes or blow a line it move much further that usualy. this can cause the seals to go. just like a seal on a shaft that gets a grove your master does the same thing now when you go moving it over that grove it can cause damage. not always but sometimes.
yea this was a little off topic so
change the fluid new is better than old less contaminates also when changing the filter make sure it is in super clean environment tranny's don't take well to dirt use those rags that don't leave lint.

How does bleeding the brakes move the cylinder farther? Most places that bleed brakes do it one maned with a vaccum pump. Even if you did it the two man way, the cylinder should not be moving any further then normal operation. It's not like you can press the pedal farther then it is possible.

The point is people don't have pre exsisting conditions with their brake systems and come in to have it flushed, then cry when it fails.

Brake systems are inspected closely because of the safety factor, which also makes it an easy sale. People just expect that a flush will fix a dead tranny. Maybe the power steering example fits a little better....
 
JeepXJ93 said:
If anyone read my other thread about tranny fluid and filter change u'll know i'm having a bit of a problem...(not to hijack) but what fluid are you all changing w/ b/c i was told not to use ATF-3...even though my owners manual and jeep dealership says to...Dextron-3 is what i should be using. I just put 4qts of ATF 3 and changed my filter...should i pay money to have it flushed and put in Dextron III??

When I was ready to change the fluid on my 96xj I asked at autozone, they looked in the book and said ATF3. Not totally satisfied I went to NAPA and asked. They said "look on the stick". It says transmission oil :-( So that evening I sat down with the owners manual. There it was on the rear cover. "For auto transmissions use ATF3". The next line said "For six cylinder models use Dexron III". Clear as mud! I wonder what the ratio of 6 cylinder auto's to 4 cyl auto is? Anyway if you have a 4.0L six cylinder xj of any year then you have a AW4 transmission and you need Dexron III. I personally put in Mobil 1 synthetic Dexron III atf last time and it seems to like it fine. I would get the wrong stuff out of there as soon as possible and as much as possible and this power flushing seems the way to get most of it out.

JoBo
 
redsand187 said:
How does bleeding the brakes move the cylinder farther? Most places that bleed brakes do it one maned with a vaccum pump. Even if you did it the two man way, the cylinder should not be moving any further then normal operation. It's not like you can press the pedal farther then it is possible.

The point is people don't have pre exsisting conditions with their brake systems and come in to have it flushed, then cry when it fails.

Brake systems are inspected closely because of the safety factor, which also makes it an easy sale. People just expect that a flush will fix a dead tranny. Maybe the power steering example fits a little better....

When you bleed brakes manually with the pedal the person pushing the pedal can push it all the way to the floor, this takes the piston in tha master cylinder and moves it further than it has ever moved before. Problem with this is that the piston in the MC will generally have some corrosion and crud build up on it and when you push it futher it can and usually does rip the seals out in the MC. Same thing with calipers, after the piston has been 'out in the air' for couple of years it also gets corroded, when you push it all the way back on to put new pads on it rips the seal and then leaks.
 
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