Changing A/T Fluid

[DMK/Happy]

To flush or to drain?That is the question..Some or saying have the a/t system pumped out , mixing old and new fluid together fluid half changed, others drain with new filter.I'm leaning towards drain and new filter only presently. The a/t is working normally,the fluid condition looks clean.Last job pending.

 

[Oldspanners]

To flush or to drain?That is the question..Some or saying have the a/t system pumped out , mixing old and new fluid together fluid half changed, others drain with new filter.I'm leaning towards drain and new filter only presently. The a/t is working normally,the fluid condition looks clean.Last job pending.

After draining and replacing the filter you can compare the old and new fluid and go from there. If needed take the banjo connector off the rhs of the gearbox, connect a hose securely to the pipe and start the car allow two litres to pump into a marked container, top up same amount and repeat until clean. Cycle through the gears, get the fluid up to temp (thermometer or Carsoft MBV2) and check level with dip stick. For 722.6 box.
Made a noticeable difference for me.

 

[DMK/Happy]

After draining and replacing the filter you can compare the old and new fluid and go from there. If needed take the banjo connector off the rhs of the gearbox, connect a hose securely to the pipe and start the car allow two litres to pump into a marked container, top up same amount and repeat until clean. Cycle through the gears, get the fluid up to temp (thermometer or Carsoft MBV2) and check level with dip stick. For 722.6 box.
Made a noticeable difference for me.

Interesting!The car will be going to indy who completed the service so far,they would do either they say, although with a mechanical pump system to clear,and that is what is concerning the pressure that is put through.

 

[malcolm E53 AMG]

I’m in the drain and new filter camp mainly due to the fact that I’m not very keen on dragging old fluid through the valve block

 

[mioba]

You wouldnt run a bath to fill a bath already half full off dirty water would you?

 

[malcolm E53 AMG]

Get some debris/sludge in the solenoids and you’ll have some fun

 

[Jim2]

I’m in the drain and new filter camp mainly due to the fact that I’m not very keen on dragging old fluid through the valve block

But during normal driving, the fluid is continually being circulated throughout all of the transmission anyway? Plus if the filter and magnets are doing their jobs correctly, only filtered fluid will be in circulated? Personally, I'm 100% in favour of the complete change method. I know that it will use more fluid, but for me anyway, its worth it. So SOP, drain pan, replace filter, refill with the same amount of drained oil. Attach drain tube to banjo connection on cooler return pipe, and pump away 2 ltr x 2ltr until fresh fluid appears. Then forget it for 40'000 Miles.

 

[Wighty]

I don’t know how dirt would get dragged through from anywhere , the filter is in the sump to stop that happening .

 

[malcolm E53 AMG]

Interesting read on the subject:

https://blog.amsoil.com/transmission-pan-drop-vs-flush-which-is-better/

 

[RhodieBill]

I’m in the drain and new filter camp mainly due to the fact that I’m not very keen on dragging old fluid through the valve block

I'm with you here!

Always just done the "Dump 'n' Fill". Usually 3 times over a period of 4-5 weeks. Filter on the last one.
By the end if it I've used just about all of 2 4lt tubs.

And I use Fuchs Titan ATF 4134, which is a Mercedes Factory-Fill ATF.

 

[alexanderfoti]

I’m in the drain and new filter camp mainly due to the fact that I’m not very keen on dragging old fluid through the valve block

When you drain the oil, fill the new oil into the sump, then undo the return line from the cooler, the oil goes like this:

Sump > filter > Pump > TC > Oil cooler > out the return line

Very little mixing goes on, its the best method on these.

 

[M80]

Doing this DIY I can see why a more regular drain and top up is attractive, with 1 filter change each 40k miles.
At a reputable Merc Indie i would pay a few quids more and ask them to do a full flush.

How many miles since last fluid change might be a consideration. As some motors have been run on a 'filled for shortened life' principle they have often done more miles on original fluid than is good, so then a flush is very desirable, in my mind.

 

[RhodieBill]

It's not uncommon for a "Full Flush" to actually destroy a Transmission.

Put this in Google and see! "does an atf flush damage a transmission"...

 

[DMK/Happy]

It's not uncommon for a "Full Flush" to actually destroy a Transmission.

Put this in Google and see! "does an atf flush damage a transmission"...

To flush or not to flush that is the 64 thousand dollar question. The following from a/t specialists .



What happens during a transmission flush?
The “simple” method of replacing the transmission fluid (often done at home) is to let the old fluid drain out and pour new fluid in to replace it, not entirely unlike an oil change. However, this method tends to leave residue in the line which can compromise the new fluid. A more accepted method is to do a full flush at a trusted auto repair shop, where the mechanic attaches the vehicle to a machine that uses the vehicle's own transmission pump to gently flush out the old fluid while pumping in new fluid simultaneously. If the line is particularly dirty, the mechanic may run a solvent through the line first to clear out debris before the new transmission fluid is introduced.


Can a transmission flush harm the transmission?
There is some speculation that a transmission flush can do more harm than good by dislodging debris along the transmission line. However, this usually only happens when the auto shop is using a machine that forces the fluid backward through the system, instead of the gentle flush method we described above. That being said, if your vehicle has gone 100,000 miles or more and you've never done a transmission flush, there's a greater chance that a flush will cause the transmission to fail, and your mechanic may advise against it.

 

[JBell]

Interesting!The car will be going to indy who completed the service so far,they would do either they say, although with a mechanical pump system to clear,and that is what is concerning the pressure that is put through.

That is how mine was done, they just plug the machine on and it pumps the old oil out, flushes it through the re-fills

 

[DMK/Happy]

After considering everything discussed here I have booked in for pan and t/c drain,using the vehicles own tranny pump to gently pump out the old fluid, new filter, seals and refill of a/t fluid.No flush through. Thanks for info.Appreciated!

 

[DMK/Happy]

A/T fluid changed pan and torque,seals,filter, really made a difference after,changing up smoothly with less revs.Hope update helps someone.