Tranny Flush?

[Cjmccoy93]

Anyone every get their transmissions flushed? I hear to never do it then I hear it doesn’t harm some vehicles and it’s the only true way to get 100% new fluid into the system.

Is the way to go to drain the pan then add new fluid, circulate, drain, add, circulate, drain etc etc a few times to get mostly new oil into the whole system?

 

[Burla]

It's just as dangerous to not flush it, most guys service their rfe by draining and replacing, this way system doesn't run dry. Look up metal thread upgrade and synthetic filter if you are gonna do it.

 

[NJMOPAR]

On my 99 Dakota with 75k the trans grenaded 3 weeks after the flush.
Never got it on another vehicle after that expensive lesson.

 

[PoMansRam]

I believe the term flush isn't accurate for this application.

ATF exchange machines that I've seen don't use pumps. They rely on the transmission's pump to pump fluid into the used fluid cylinder via the cooler lines, while new fluid in the exact volume is forced back in thru the return line. It's just a transfusion of sorts. Perfectly harmless and beneficial IMO.

 

[kurek]

There's an insane amount of information and misinformation and mystery about transmission maintenance... so much that I'm not even going to talk about what I think should or shouldn't be done (except please never give Kilmer your attention he is not doing you a service)

But to help disambiguate the process of fluid exchange it's a good idea to watch how it's done so at least it isn't a mystery. This video has branded promotion but I think it gives a fair and unvarnished demonstration of what the fluid exchange machines are actually doing


- just ignore the branding and watch what's being done. Might help reduce the voodoo aspect a little and that will get us closer to a true and actionable decision.

Something to take note of is that the operator has the option of adding other substances to the transmission like a flush and a conditioner. Remember that when the transmission fluid passes through the cooling system and returns to the pan to be picked up by the pump it's going to be a mix of old and new fluid so if you have a 10 quart system and use the exchange system to exchange in 5 quarts, you may only truly get 3 or 4 quarts actually changed in because after some of the new fluid gets into the pan, you'll be exchanging some of the new fluid straight back out again. There is no perfect loop of "first in, last out" for fluid exchange because it's a wet sump.

 

[Cjmccoy93]

kurek

doesn’t ready seem bad at all, there’s just so many bad experiences! Seems like a no brainer really, crazy that there’s so many things that eff up after doing them though, from what I hear and read anyways...

 

[Sherman Bird]

On my 99 Dakota with 75k the trans grenaded 3 weeks after the flush.
Never got it on another vehicle after that expensive lesson.

That trans was going to grenade anyway. Flushing an otherwise healthy transmission never hurt it.

 

[AE5548]

I believe the term flush isn't accurate for this application.

ATF exchange machines that I've seen don't use pumps. They rely on the transmission's pump to pump fluid into the used fluid cylinder via the cooler lines, while new fluid in the exact volume is forced back in thru the return line. It's just a transfusion of sorts. Perfectly harmless and beneficial IMO.

Well said. Flushing is never recommended. Often times they talk of flushing some solvent through your tranny which also forces out the old fluid. Never, ever do this. But pushing out the old fluid with new fluid is certainly a fine idea and will not cause any harm when done right. Just don't use any sort of solvent or "cleaner"

 

[Lyle Longboat]

For a newly rebuilt transmission, 5 speed, should I be changing the fluid every 6 months with oil? I do run 37” tires. Going to get the transmission fluid changed next Month while regearing. Just thought I’d ask.

 

[Octane]

I've almost always drained/replaced trans fluid every 30k and filter every100k without any issues.I even change my standard shift trans every 30k.Depending on how the miles was put on I might go a bit further than 30k.Diff fluids every 40k or so.

 

[Sherman Bird]

I've almost always drained/replaced trans fluid every 30k and filter every100k without any issues.I even change my standard shift trans every 30k.Depending on how the miles was put on I might go a bit further than 30k.Diff fluids every 40k or so.

Good job!

 

[Octane]

Every August, I'd do a full maintenance on my 1990 GMC Suburban SLE. Trans filter and ffluid, new fuel filter, new air filter, oil and filter, differential, brake fluid flush. The fella I eventually sold that vehicle to drove it past 400,000 mark before he had it towed to salvage.

I have a written record book of every vehicle I own and it helps immensely.I have had vehicles I dont drive much and I would think it wasn't that long ago when I done something to it and then my record book shows 1, 2 or 3 years have gone by... lol

 

[sirdumpsalot]

I have a written record book of every vehicle I own and it helps immensely.I have had vehicles I dont drive much and I would think it wasn't that long ago when I done something to it and then my record book shows 1, 2 or 3 years have gone by... lol

so do I, except it's an excel doc. Very organized

 

[Sherman Bird]

so do I, except it's an excel doc. Very organized

27 of my 45 years as an ASE and factory trained technician were spent as an automatic transmission specialist (GM & Ford). This gives me an educated and deeply experienced perspective way beyond you tubers, buddies at the bar, and general voo-doo urban legends steeped in anecdotal horror stories.

Now for facts:Flushing an automatic transmission to address an existing problem with shift issues, delayed engagements, etc. are going to be fraught with negative results in the vast majority of attempts to "fix" a more deeply rooted problem.
Flushing a perfectly fine working transmission for maintenance purposes early in it's life and at regular intervals thereafter is very safe and problems in that scenario are more rare.

I flushed my auto trans on my 2002 Sequoia at 260,000 miles, but this goes back to when the vehicle was new. This is the original trans which works still perfectly at 280,000 miles, and, although THAT is merely anecdotal, the fact stands that I've been involved in untold thousands of automatic transmission repairs, maintenance, and diagnostics over the scope of my career.

I recommend and DO practice only doing drain and refills along with purging the fluid from a cooler line to get the converter oil out as well on an older, non-maintained transmission.... with great results.

I'm not here to argue with or refute anyone; just share what I know from training..... At least, to me, an automatic transmission is NOT a mysterious black box. I hope this helps YOU to make an informed decision to answer your question, and to address your doubts. Peace!

 

[sirdumpsalot]

27 of my 45 years as an ASE and factory trained technician were spent as an automatic transmission specialist (GM & Ford). This gives me an educated and deeply experienced perspective way beyond you tubers, buddies at the bar, and general voo-doo urban legends steeped in anecdotal horror stories.

Now for facts:Flushing an automatic transmission to address an existing problem with shift issues, delayed engagements, etc. are going to be fraught with negative results in the vast majority of attempts to "fix" a more deeply rooted problem.
Flushing a perfectly fine working transmission for maintenance purposes early in it's life and at regular intervals thereafter is very safe and problems in that scenario are more rare.

I flushed my auto trans on my 2002 Sequoia at 260,000 miles, but this goes back to when the vehicle was new. This is the original trans which works still perfectly at 280,000 miles, and, although THAT is merely anecdotal, the fact stands that I've been involved in untold thousands of automatic transmission repairs, maintenance, and diagnostics over the scope of my career.

I recommend and DO practice only doing drain and refills along with purging the fluid from a cooler line to get the converter oil out as well on an older, non-maintained transmission.... with great results.

I'm not here to argue with or refute anyone; just share what I know from training..... At least, to me, an automatic transmission is NOT a mysterious black box. I hope this helps YOU to make an informed decision to answer your question, and to address your doubts. Peace!

sounds like this is something worth paying the money for the dealership to do?

 

[Octane]

27 of my 45 years as an ASE and factory trained technician were spent as an automatic transmission specialist (GM & Ford). This gives me an educated and deeply experienced perspective way beyond you tubers, buddies at the bar, and general voo-doo urban legends steeped in anecdotal horror stories.

Now for facts:Flushing an automatic transmission to address an existing problem with shift issues, delayed engagements, etc. are going to be fraught with negative results in the vast majority of attempts to "fix" a more deeply rooted problem.
Flushing a perfectly fine working transmission for maintenance purposes early in it's life and at regular intervals thereafter is very safe and problems in that scenario are more rare.

I flushed my auto trans on my 2002 Sequoia at 260,000 miles, but this goes back to when the vehicle was new. This is the original trans which works still perfectly at 280,000 miles, and, although THAT is merely anecdotal, the fact stands that I've been involved in untold thousands of automatic transmission repairs, maintenance, and diagnostics over the scope of my career.

I recommend and DO practice only doing drain and refills along with purging the fluid from a cooler line to get the converter oil out as well on an older, non-maintained transmission.... with great results.

I'm not here to argue with or refute anyone; just share what I know from training..... At least, to me, an automatic transmission is NOT a mysterious black box. I hope this helps YOU to make an informed decision to answer your question, and to address your doubts. Peace!

I must say it's great to hear someone say all this.I've done my own fluid changes even on older units with no problems.My friends and others have always ridiculed and made out like I was a fool for servicing transmissions.They think they are "mysterious" mechanical things that should never need to be serviced.I've done all mine since the 1970s.Maybe we both know "voo doo science" lol

 

[Dodge 1500 4X4]

All I know of is this, Doing a fluid exchange is over working the front pump in the transmission, these exchange machines have there own pump, very important to change the transmission filter before doing this fluid exchange, lets see the valve body and transmission gets is fluid from the pan if the filter is already clogged the front pump has all that work to suck it out of the pan now we got a pump issue, I just dump the pan, change the filter and torque convertor if it has a plug, some I've seen disconnect the cooler lines to drain the transmission, again you're over working that front pump again, And if i check the dipstick on older vehicles, if the fluid is dark and has that burned smell i leave it alone that dark fluid is holding the trans clutches together, And if some Einstein on a vehicle for sale has changed the fluid when you pull the dipstick, I close the hood and walk away!!

 

[Octane]

If the filter is clogged...then its too late anyway... the tranny is toasted.A tranny pump works all the time.Regardless if the filter is clogged.A tranny pump wears out over many miles,and leaks and loses its pumping ability.

 

[Sherman Bird]

If the filter is clogged...then its too late anyway... the tranny is toasted.A tranny pump works all the time.Regardless if the filter is clogged.A tranny pump wears out over many miles,and leaks and loses its pumping ability.

There are 3 type of trans pumps these days.... Variable displacement vane style pumps, and 2 designs of gear-in-gear drive pumps. The 2 gear designed pumps have the ability to dead head and are positive displacement. This means they can self destruct at terminal pressure, so flushing these powerful pumps is NEVER going to strain the poor thing into failure. The Vane style pumps will sound like a cat when it gets air or low pressure. The vane pump is designed to consume less power and have less parasitic loss at lower demands. (cruising slowly through a neighborhood at light throttle, for example)

 

[Silby]

On my 99 Dakota with 75k the trans grenaded 3 weeks after the flush.
Never got it on another vehicle after that expensive lesson.

Same thing happened to my 2002 Dakota