Transmission flush

I have read LOTS about how to properly flush (or not to flush) my auto transmission. One article in particular impressed me with their reasoning but it is an old article.
What is the current wisdom? Flush or not? What type of flush....cooling lines, vacuum, etc. I live in Atlanta so I called some local shops. One shop said they never flush. They only drain and fill. A Toyota dealer said they use a vacuum system, another shop said they flush by using the cooling lines, a national shop said they were not aware that the transmission had a replaceable filter.

HELP!!! BTW, can anybody suggest a good shop around Atlanta?

 

If it's got high mileage, don't flush it! I did this to a car once that had 180k miles and it completely fucked up the tranny and I had to sell the car. After that I am completely anti flush, will just do fluid changes from now on.

 

Don't worry about flushing. Just do a periodic drain and fill. If you're picky about old fluid, drain & fill, then drive around so the old and new oil mixes, drain and fill once more.

 

I've done 2 auto tranny flushed on 2 different cars that I have owned. Never had a problem. One was my 4-Runner and other was a Altima v6. Both had over 100k miles and I happy with the results.

 

I have serviced approx 4000 automatic transmissions . Does this make me a pro with the A750 series transmission in your Tacoma? NO , but I will try and explain
Years ago , most of the shifting was controlled by hydraulics or mechanical spool valves inside the valve body . When a customer brought their transmission into my transmission shop to have it flushed ( without removing the pan and filter ) there was a possibility of forcing the material from the bottom of the transmission pan into the valve body causing the spool valves to stick .This was very common with the popular GM trucks 700R4 and Chrysler mini van A670 transmission.
As transmissions get newer , electrical solenoids and sensors are taking place of the many mechanical spool valves in the valve body . Solenoids now have a larger bore. In saying this , flushing a transmission can now be performed with less possibilities of hydraulic spool valves getting all gummed up and stuck.
If you plan to flush , get quotations from a shop that uses a flushing machine with the pan and filter removed .They are the best flushing machine to use because this machine guarantees the pan was removed before the flush was performed .
This method attaches the machine’s line out to the pump intake. The process transfers fluid through the vehicle and into a drainage pan, completely flushing the system. When cleared, new fluid is supplied to fill up the car. This process requires the complete removal of your pan and filter and a new filter and pan are installed at the end. This requires more time, a few extra quarts of fluid (around 20) and costs a bit more, but it is a much more complete, ideal procedure. - See more at: http://www.transmissionrepaircostgui....YDlT9xaq.dpuf
Once the pan and filter have been removed , connect the flushing machine to the filter suction line in the valve body casting , start the vehicle and flush away .
Dont go to a shop that uses a cooling line flushing machine WITHOUT MAKING SURE THE PAN IS REMOVED FIRST .The guy telling you to flush without removing the pan first must have ESP ? How does he/she know the condition of your transmission . Remove the pan first regardless of miles.
All Flushing machines use your transmission pump to mix/force the old oil out and your engine has to be running to turn the transmission pump .Flushing machines will Never flush fluid backwards through a transmission or what some quick lube shops call reverse flushing / backflushing . Your transmission pump only turns one way so dont let those guys fool you into thinking they have a special super flushing machine .
Note: Some service centers use machines that add additional force to blast fluid and/or cleaning solution through the system. This is NEVER a good idea as this can damage seals and/or lodge sludge in places it shouldn’t be as mentioned above. - See more at: http://www.transmissionrepaircostgui....B2SaFB52.dpuf
If the truck was mine or a customer of mine , I would get that old stuff outta there .
There are 11 duties transmission fluid carries out inside the transmission .New fluid will help to prevent transmission failure .

 

flush it completely and replace with new synthetic tranny fluid.

to flush it drain the pan then replace the drain plug. add 4 quarts of new synthetic tranny fluid (I used Valvoline MaxLife (ATF) Automatic Transmission Fluid)

now disconnect the rubber transmission line hose at the passenger side bottom of the radiator and add a short hose to the disconnected end. fluid only comes out one of them but you want to run both to the drain pan just to be safe so id doesn't make a big mess. when the engine is running the fluid comes out like a steady stream from a slow running faucet so its not going to squirt out or splash everywhere on you.

now start the truck and run it for 15 seconds then shut it off and add another 2 quarts then repeat. its best to do this with a helper so you can wait to see when the fluid stops coming out to stop the engine and then add more fluid and this allows you to watch the color as it comes out so you know exactly when to stop flushing when it comes out nice and red and clean signaling all the fluid is now new. then reconnect the transmission cooler lines and check fluid levels. shift through all gears a few times then recheck the levels and when you are sure its filled correctly take it out for a 20-30 mile ride and back then recheck fluid levels and make sure there are no leaks.

when I finished I had used two of the gallon sized jugs of tranny fluid and the old stuff looked brownish muddy colored so it was definitely past its lifetime and I had 120k miles on it. my tranny shifts smoother and runs quieter now with the synthetic fluid. I think the tranny holds 1 1/2 gallons of fluid and the other 1/2 gallon was wasted in the flushing process. if you have too much fluid when its all said and done just take the drain plug out for a second or two to drain the excess.

as you can see it very simple and easy to do this in your own driveway in an hour and this method doesn't force anything into your tranny under pressure or add any pressure to the system that it wasn't intended to go that way so its using the tranny itself to pump the new fluid into the system which is the safest and easiest method to flush your tranny.

 

Get a total BG transmission flush done,, none better

 

It's alright to flush if the transmission has been serviced regularly, but if you are unsure, don't risk it.

 

Hey gearcruncher - that's some great information...thank you!

Ed

 

Lordy! This forum is wonderful. I got the exact info that I need.

Thanks all.

 

I acquired mine with 169000 and the grand fluid was ack and burned. I have done 7 fluid changes and I just added Lucas in the last one. It runs smooth and nice. Don't flush!!!

 

If you have never flushed the trans then it's recommended that you DO NOT flush it.

If the trans has been flushed regularly then by all means keep doing it.

I get mine flushed about every 30-35K miles. So far the trans has lived 150K and still as good as new.

 

this is an old myth based on older trannys that had different components in them. on those a flush removed sediments circulating in the fluid that provided extra traction for the friction bands to grip so fresh new fluid cause old worn bands to lose traction and the tranny would start slipping necessitating a rebuild.

the trannys today are much better and work completely differently (no more bands) so there is little risk in replacing fluids on high mileage vehicles today. if you had loose sediments in your tranny with todays vehicles it would not shift at all and the whole myth of replacing fluid will make it stop working is based on removing sediments the tranny is using to keep gripping the clutches inside it.

 

I don't believe it's an old myth. Sludge and gunk from 100K miles is still sludge and gunk. Flushing a trans has a much higher likelyhood of knocking that stuff loose.

Transmissions aren't all that different today than they were 20 yrs ago and the passages that control fluid movement are still tiny. Stop one up and it bye bye transmission.

 

This is what I’m thinking about doing drain out 3 liters or so and then fill and then do that again. I’m still undecided if I want to even touch it. I have 70k miles.