Opinion - Transmission Flush

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Originally Posted By: steve20
I keep the Accord trans happy with a once/year (30 K miles) drain. Luckily Honda has a drain plug-3 quarts out 3 quarts (Honda fluid) in-every time. There is an inline magnetic filter I've got to get around to one of these (cooler) days.
135K on the car with no issues
Trans fluid flushers can be evil machines...............


Steve

that is exactly the right thing to do with honda transmissions! i use this method myself, and you'll be surprised how many customers will see this and get angry because they wanted the machine.
 
This is a rule of thumb given to me by a transmission mechanic. He said if the vehicle hasn't had the fluid in for more than 30K miles, then it's OK to have it flushed. After it's been in for more miles than that, the fluid starts to break down and it's possible it will have particals in it that are large enough to clog passage ways in the transmission. Doing a flush on such a transmission can cause these particals to travel through the transmission and lodge in passage ways causing shifting problems. For transmissions like this, it's better to just drain the fluid and change the filter. This minimizes the risk of getting passage ways clogged.
 
Originally Posted By: grampi
This is a rule of thumb given to me by a transmission mechanic. He said if the vehicle hasn't had the fluid in for more than 30K miles, then it's OK to have it flushed. After it's been in for more miles than that, the fluid starts to break down and it's possible it will have particals in it that are large enough to clog passage ways in the transmission. Doing a flush on such a transmission can cause these particals to travel through the transmission and lodge in passage ways causing shifting problems. For transmissions like this, it's better to just drain the fluid and change the filter. This minimizes the risk of getting passage ways clogged.


x2, well said and agreed 100%
 
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Originally Posted By: exranger06

This is exactly why I made my previous post: To dispell this myth. A flush does NOT dislodge any gunk at all. In fact, it's not really a flush at all. The "correct" term is fluid exchange.


exranger06- you do realize you're potentially talking about 2 different things when you say "flush", right? Under the average shop's terms, a transmission "flush" may or may not mean "fluid exchange". It could also mean what mechanicx refers to- a chemical flush with an external pump instead of your own transmission's pump. Many a transmission shop will recommend against any type of "flush" on a high mileage transmission with unknown maintenance history, and for good reason, I believe. Even if you're talking about an "exchange", how do you know it could never damage a transmission vs. dropping the pan? I had a T-Tech flush (fluid exchange) with Mobil 1 Synthetic ATF on a 93 Landcruiser with 120k and unknown maintenance history, and the transmission, which had worked perfectly with no sign of any problem, quickly took a dump afterward (sun gear failure). Coincidence? The many transmission shops I took it to for estimates afterward didn't think so, and neither do I. If you read up on various forums, you'll see this is not an isolated case. Changing less of the fluid, and in a less invasive manner by dropping the pan and refilling the fluid is less traumatic to existing deposits than a full exchange.
 
Originally Posted By: moving2
Originally Posted By: exranger06

This is exactly why I made my previous post: To dispell this myth. A flush does NOT dislodge any gunk at all. In fact, it's not really a flush at all. The "correct" term is fluid exchange.


exranger06- you do realize you're potentially talking about 2 different things when you say "flush", right? Under the average shop's terms, a transmission "flush" may or may not mean "fluid exchange". It could also mean what mechanicx refers to- a chemical flush with an external pump instead of your own transmission's pump. Many a transmission shop will recommend against any type of "flush" on a high mileage transmission with unknown maintenance history, and for good reason, I believe. Even if you're talking about an "exchange", how do you know it could never damage a transmission vs. dropping the pan? I had a T-Tech flush (fluid exchange) with Mobil 1 Synthetic ATF on a 93 Landcruiser with 120k and unknown maintenance history, and the transmission, which had worked perfectly with no sign of any problem, quickly took a dump afterward (sun gear failure). Coincidence? The many transmission shops I took it to for estimates afterward didn't think so, and neither do I. If you read up on various forums, you'll see this is not an isolated case. Changing less of the fluid, and in a less invasive manner by dropping the pan and refilling the fluid is less traumatic to existing deposits than a full exchange.


Exactly, and doing changes rather than flushes also means any deposits that may come loose are more likely to end up in the new filter instead of clogging up passage ways.
 
Those reverse flow flushers should be flushed, if you catch the drift. Those are the machines that have given the term "transmission flush" the bad name and are the things tearing up transmissions for the reasons aptly stated above.

Fluid exchange is a kinder, gentler way to do it that isn't as harmful.

The cure for all the "gunk" worries is to install an inline filter in the return line from the cooler. It will catch anything that breaks loose and, IMO, is a must have. The Magnefine is probably the best known of this type of filter, but there are others.
 
Originally Posted By: moving2


exranger06- you do realize you're potentially talking about 2 different things when you say "flush", right? Under the average shop's terms, a transmission "flush" may or may not mean "fluid exchange". It could also mean what mechanicx refers to- a chemical flush with an external pump instead of your own transmission's pump. Many a transmission shop will recommend against any type of "flush" on a high mileage transmission with unknown maintenance history, and for good reason, I believe.


I have no experience with "flushes," so I can't really comment on that. I still stand by everything I said about fluid exchanges, though.

Originally Posted By: moving2
Even if you're talking about an "exchange", how do you know it could never damage a transmission vs. dropping the pan?


Umm, I just explained that in my previous post.

Originally Posted By: moving2
I had a T-Tech flush (fluid exchange) with Mobil 1 Synthetic ATF on a 93 Landcruiser with 120k and unknown maintenance history, and the transmission, which had worked perfectly with no sign of any problem, quickly took a dump afterward (sun gear failure). Coincidence? The many transmission shops I took it to for estimates afterward didn't think so, and neither do I.


I believe it was.

Originally Posted By: moving2
If you read up on various forums, you'll see this is not an isolated case. Changing less of the fluid, and in a less invasive manner by dropping the pan and refilling the fluid is less traumatic to existing deposits than a full exchange.


I firmly believe the whole "flushing destroys transmissions myth" started like this: Some guy never maintains his transmission properly and never changes the fluid
31.gif
and eventually he starts having problems. At this point his trans is toast from poor maintenance and nothing will save it. But NOW he finally thinks “Oh maybe I should change the fluid and it’ll fix it.” So he gets the fluid changed, his trans dies shortly after so he thinks it must be from the fluid, not the years of neglect.
smirk2.gif
 
Originally Posted By: moving2
I had a T-Tech flush (fluid exchange) with Mobil 1 Synthetic ATF on a 93 Landcruiser with 120k and unknown maintenance history, and the transmission, which had worked perfectly with no sign of any problem, quickly took a dump afterward (sun gear failure). Coincidence? The many transmission shops I took it to for estimates afterward didn't think so, and neither do I.


Originally Posted By: exranger06

I believe it was.


Originally Posted By: moving2
If you read up on various forums, you'll see this is not an isolated case. Changing less of the fluid, and in a less invasive manner by dropping the pan and refilling the fluid is less traumatic to existing deposits than a full exchange.


Originally Posted By: exranger06

I firmly believe the whole "flushing destroys transmissions myth" started like this: Some guy never maintains his transmission properly and never changes the fluid
31.gif
and eventually he starts having problems. At this point his trans is toast from poor maintenance and nothing will save it. But NOW he finally thinks “Oh maybe I should change the fluid and it’ll fix it.” So he gets the fluid changed, his trans dies shortly after so he thinks it must be from the fluid, not the years of neglect.
smirk2.gif



Maybe you didn't read the part about the dealer and (3) transmission shops I took it to, ALL of whom attributed it to the fluid exchange, and all of whom said they'd seen this "coincidence" happen many times before. Believe what you want based on your single sample point. I'll believe professional transmission rebuilders who have see many more samples than either of us will see in a lifetime.

Nice little theory, though. And by all means you go right on sticking to it. Just try telling it to a few transmission rebuilders next time and let us know what you hear (beyond the laughter, that is).
smirk2.gif
 
Moving2: It would be interesting to compare the various types of "flush" machines and see how they operate. It could be there is a particular type that is the focus of the problems. I would more suspect operator error, as a mchine that could be proven to "eat" transmissions would (or should) be not long for the market... and it's manufacturer likely in court.

But, given that the fluid exchange machines (that I have seen) generally run the fluid through the lines at approximately the same rate of flow as the transmission will do on it's own, and in the same direction, I cannot see how it could be harmful. Especially if the old oil is drained out past the cooler and new oil is fed back into the trans via the return cooler line, which was the way of the machine I saw recently (sorry, wasn't a brand name I remember or recognized). Again, the actual machine and setup may tell the tale. If the new oil is pumped in before the cooler, there is some potential for contamination.

Now reverse flush... sure. Bad deal potentially. There are cases of reverse flush machines blowing the filter out of it's canister, but I suspect those examples come from operator error. Can't imagine a machine and it's manufacturer not accounting for that.

Assuming a down the road problem, where contaminants are loosened and later come totally free, well, that could happen with a pan drop when the new oil (with it's fresh detergents) is added. A flush that used a solvent or cleaning fluid could have a similar "delayed reaction." But, again, if an inline filter is installed on the cooler return line, the danger is mitigated, if not eliminated.

I contend that any fluid exchange should start by dropping the pan and changing the pan filter. Many transmissions have magnets in the pan that collect the ferrous material that makes up 50 percent of total transmission contaminants. This is especially important the first time out, as transmissions generate 75 percent of their total lifetime of contaminants within the first 5000 miles of use (a combo of built in "Type 1" contaminants and "Type 2" break in material). After that first one, maybe you could skip the pan drop, but I wouldn't.

Lastly, lamant the loss of the torque converter drain. It's loss the root of all the problems. I have carefully drilled several converters in situ and tapped them for a plug... but that may not be possible in all cases. And it's definitely not done without research, forethought and steady hands.
 
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Jeez- I wish the Monk was on this coast-I'd keep him very busy with all of the work I used to enjoy doing when I didn't have this level of job and family responsibilities....


Steve
 
Originally Posted By: exranger06
Originally Posted By: moving2


exranger06- you do realize you're potentially talking about 2 different things when you say "flush", right? Under the average shop's terms, a transmission "flush" may or may not mean "fluid exchange". It could also mean what mechanicx refers to- a chemical flush with an external pump instead of your own transmission's pump. Many a transmission shop will recommend against any type of "flush" on a high mileage transmission with unknown maintenance history, and for good reason, I believe.


I have no experience with "flushes," so I can't really comment on that. I still stand by everything I said about fluid exchanges, though.

Originally Posted By: moving2
Even if you're talking about an "exchange", how do you know it could never damage a transmission vs. dropping the pan?


Umm, I just explained that in my previous post.

Originally Posted By: moving2
I had a T-Tech flush (fluid exchange) with Mobil 1 Synthetic ATF on a 93 Landcruiser with 120k and unknown maintenance history, and the transmission, which had worked perfectly with no sign of any problem, quickly took a dump afterward (sun gear failure). Coincidence? The many transmission shops I took it to for estimates afterward didn't think so, and neither do I.


I believe it was.

Originally Posted By: moving2
If you read up on various forums, you'll see this is not an isolated case. Changing less of the fluid, and in a less invasive manner by dropping the pan and refilling the fluid is less traumatic to existing deposits than a full exchange.


I firmly believe the whole "flushing destroys transmissions myth" started like this: Some guy never maintains his transmission properly and never changes the fluid
31.gif
and eventually he starts having problems. At this point his trans is toast from poor maintenance and nothing will save it. But NOW he finally thinks “Oh maybe I should change the fluid and it’ll fix it.” So he gets the fluid changed, his trans dies shortly after so he thinks it must be from the fluid, not the years of neglect.
smirk2.gif


i agree that a flush shouldn't hurt a transmission that is in perfect shape, but that can be hard to judge these day, electronically controlled transmissions can compensate for slippage and other issues, masking that problem.so often time with modern cars the owner will not be aware of a problem until it gets to a point that the trans computer can no longer compensate for, hence the reason why you hear so often "my trans died today." 15 yrs ago most owners would see it coming for sometime before it would totally be gone.
 
My $.02

#1 Never change the fluid on an A/T whcih has in excess of 60k miles on the original fluid because the new fluid with its fresh additive pack can dislodge crud from a place where it's doing no harm to a place where it does some harm. In addition the clutch pack material floating around in the old fluid is helping to prevent the A/T from slipping. New ATF = no material which means possible slipping.

#2 Reverse flow machines are a no-no. They add premature wear to the internal seals. Pan drop every 30k miles is least likely way to screw up an A/T but depending on the A/T you're only getting about ~20-40% of the fluid (rest is in the TQ Converter).

#3 Shops have seen well maintained A/T's last both 250k and 100k miles as well as neglected A/T's last 250k and 100k miles. In the end there's just no telling.
 
Originally Posted By: Jim Allen
I contend that any fluid exchange should start by dropping the pan and changing the pan filter. Many transmissions have magnets in the pan that collect the ferrous material that makes up 50 percent of total transmission contaminants. This is especially important the first time out, as transmissions generate 75 percent of their total lifetime of contaminants within the first 5000 miles of use (a combo of built in "Type 1" contaminants and "Type 2" break in material). After that first one, maybe you could skip the pan drop, but I wouldn't.


I agree!! I don't understand why anybody would want to do a flush/exchange WITHOUT dropping the pan for the sole purpose of cleaning the magnet and changing the filter.

I know there's lots of debate between flush and exchange. But dropping the pan and using a little compressed air (30psi) to blow oil out of the oil cooler and torque converter will get MOST of the ATF out. You can always exchange the ATF after 500miles to feel confident about getting all the fluid out.

I found it easiest to drain out the dipstick with a fluid extractor first. This saves me the ATF shower. Dropping a pan that is 95% empty isn't so bad. On the OPs Jeep I think it's 12 bolts and spin-on filter. Check for a reusable rubber gasket. Here's a link on my extractor write up: https://bobistheoilguy.com/forums/threads/recommended-mityvac7300.132514/

My Jeep GC SRT8 @ 18k miles had a surprising amount of gunk on the magnet (break in debris) and while the fluid was CLOSE to the original color changing the fluid improved the lag time when shifting from R>D or D>R. The OEM fluid was overpriced, but the pancake filter was $22 was cheap enough.

I'm not convinced that ATF should have such long OCIs. Espeically when the transmissions shed so much metal during break in. Whey have those chunks in the system for long periods?
 
JUst had a pan drop done on my rebuilt dodge transmission. The showed me what appeared to be small brass slivers in the pan, but very few, but the magnet was coated. This was a 50k pan drop after rebuilt. Added back new fluid and one bottle lubegard, am crossing my fingers , it still shifts good though.
 
Originally Posted By: santov
But dropping the pan and using a little compressed air (30psi) to blow oil out of the oil cooler and torque converter will get MOST of the ATF out.
My Jeep GC SRT8 @ 18k miles had a surprising amount of gunk on the magnet (break in debris) and while the fluid was CLOSE to the original color changing the fluid improved the lag time when shifting from R>D or D>R. The OEM fluid was overpriced, but the pancake filter was $22 was cheap enough.


As a long term SRT8 owner (august 05) I would definitely NOT recommend any compressed air be applied to the trans as there are components in the valve body that could be harmed.

The OEM fluid is standard ATF+4, available cheap at any store.
The filter is MB Part # A 140-277-00-95 and costs 18 bucks at my local Benz dealer. The gasket is re-useable.

Also, the lag in shifting from drive to reverse or back is programming and unlikely to be affected by any fluid changes.

We do seem to see that the trans manufactured in Kokomo IN have issues not seen in the earlier Mercedes AMG units. But generally a fantastic box up to around 550 hp.
 
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