Can doing a transmission fluid flush/change damage the trans?

[poser]

Was talking the other day with my dad. Just car talk or whatever and mentioned I was going go flush the trans. He said be careful, if it's got a ton of miles and it's never been done, it may actually be worse for it. He told me about an old Ford we use go have, I guess when I was a kid, that he did that one, and with in a few months the trans went out.

My runner has 163k miles. Is a trans flush a bad idea? I've only had it a few months and I don't think it's ever been done.

 

[T4R2014]

Doing a flush is completely fine. The main difference is what is used to do the flush. NEVER use a flush machine that has a separate pump to "power flush" old fluid out. Instead, use a machine that utilizes the transmission's own pump to move the old fluid out and new fluid in.

 

[TheeMikeB]

Or you can just do the 'poor man flush'. Disconnect the return line from the rad and put it to a bucket, turn engine on... let a about 2 qts pump out, shut it off, add 2 qts... repeat till fluid comes on clean. Takes about half hour.

 

[poser]

Or you can just do the 'poor man flush'. Disconnect the return line from the rad and put it to a bucket, turn engine on... let a about 2 qts pump out, shut it off, add 2 qts... repeat till fluid comes on clean. Takes about half hour.

This is the route in planning to go. That or someone posted a YouTube link, where a mechanic was letting the engine run, the the trans out flowing into a bucket and he was adding fluid as it ran.

What's a good trans cooler? I've seen some post that they bought one off amazon.
If I'm going to do a flush, might as well install a cooler.

 

[Myrunr2010]

Semi related ... Do these trucks have a trans filter and all? I've got a manual transmission, so just a curiosity question. I've heard in general to never change your trans fluid without changing the filter out

 

[the great him]

the autos dont really have a trans filter, they have a mesh screen in the pan that just keeps the big stuff out.

id say go with a B&M either 70624 or 70628. personally i like the 70264 better, its bigger and cools better. you could also add a inline filter like a magnefine filter Magnefine Inline Transmission Power Steering Filters get one for the automatic trans missions 3/8" fittings they are cheap, disposable and very easy to install/change. i use them

 

[Tsfc]

Hey buddy, I doubt there is any real harm a flush could do,,,but if you are like me and play it safe with that sort of thing my humble advice would be to drop the pan, clean, and just do a drain and fill during the next 2 or 3 oil change intervals. By that time you will have healthy new fluid anyway. Best of luck!

 

[AZ4Running]

If your trans is already worn out and slipping a flush or fluid swap is definitely not going to help. In that case yes it can hurt the trans more. I have flushed more auto trans' than i can count being an auto mechanic and i have never had a trans go out after a flush as long as the trans was healthy. I have also used flush machines that use the trans pump to swap the fluid and one with a built in electric pump as well as doing it the old fasion way of draining and adding until fluid is clean. None have ever cause any issues in my experience. Regular servicing of the trans is what keeps them operating normal ams from premature wear and failure. Its like not changing your engine oil every 3k miles, trans service should be done every 30k or sooner if under extrem conditions imo.

 

[19963.4lsr5]

Just go to Walmart and buy 4 gallons of the SuperTech dex 3 fluid and pull the drain plug and drain and fill three times. Driving a couple miles between them. I drove a work stretch between the drain and fills. After the second cycle I added a magnefine filter into the cooler line. After the third drop the pan and change the factory filter and clean the magnets in the pan and add the Trans fluid flavor of your choice. After 1 year replace the magnefine filter.

 

[ben550]

I did a transmission fluid flush on my 04 with 136,000 miles on it. Disconnected the return line and pumped the old fluid out into a bucket while I added new fluid in through the dip stick. Been running nice ever since 163,000 and counting...

No issues. I wanted to get out all the old fluid and replace it with the new stuff rather than mix it and "replenish" the old fluid. I did drop the pan, replaced the "filter" and cleaned off the magnets. I too read about all the damage you could do to your transmission prior to doing the job. I was nervous but was confident enough that it was fine after reading several posts by people who had done it already.

I will do another complete flush when I hit 200k... but I probably will not drop the pan. I only did that cause I bought it used with 134k on it and wanted to make sure it was all good in there.

 

[Myrunr2010]

I've run some of the tranmission "fix" stuff that lucas sells throughmy wifes car (protege5) and my old f-150. Its not miracle fix or anything, but I think its helped them shift a little more smooth

 

[Nunyabiz]

Just take it to a T-Tech machine with about 15+ quarts of fresh Synthetic ATF and have fully replace as much as they can which is probably about 95%.

I think people get confused with the word "Flush" some think about the old days when they used to force in fluid or cleaner under high pressure, THAT you do NOT want.

Just use the trucks own pump to slowly push in fresh fluid, either DIY the slow way a quart or two at a time which takes two people to do it right or a T-Tech machine.