How difficult is tranny flush??
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From: Milton/Westport, MA USA
me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe; daughter: 2017 GLC SUV
How difficult is tranny flush??
My indie mechanic seems to be intimidated by the lack of a dipstick, while spark plugs and aux battery don't bother him at all. When he did brakes last year he made sure to buy all parts from the dealer which was unnecessarily expensive.
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From: In the Shadow of the Tetons
2013 ML350 Bluetec
The service is a drain and fill, not a flush. I've done it in my driveway without a lift. It's messy. Unbolt the transmission pan, replace the filter, replace pan, fill to proper level (specific fluid temperature!). The parts are all available as a kit fro FCPRuro or Pelican Parts etc and a how-to video can be found somewhere. A scan tool is helpful during the refill to assure the proper temperature at overflow.
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From: Milton/Westport, MA USA
me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe; daughter: 2017 GLC SUV
Sounds like what he’s afraid of: how does one fill to correct level with no dipstick? I’m sure he has scan tools but none Mercedes-specific; how does that inform the fluid level?
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From: In the Shadow of the Tetons
2013 ML350 Bluetec
The refill is performed by pushing fluid into the transmission pan until the fill standpipe (plugged into the drain hole inside the pan) overflows at a specified temperature. Once the fluid overflows at that temperature, the drain/fill hole is plugged and you're done.
Draining the fluid is done at the same hole, but the filler standpipe must be dislodged by prying it out of place with a screwdriver or some such. That tower (standpipe, whatever) remains fallen in the pan until the pan is removed from the vehicle.
It'll all be much more clear when you see what is in the service kit and watch a video or two. Making sure the fluid temperature is correct is the only really important part, the rest is just messy.
The transmission temperature can be read with a scan tool.
Draining the fluid is done at the same hole, but the filler standpipe must be dislodged by prying it out of place with a screwdriver or some such. That tower (standpipe, whatever) remains fallen in the pan until the pan is removed from the vehicle.
It'll all be much more clear when you see what is in the service kit and watch a video or two. Making sure the fluid temperature is correct is the only really important part, the rest is just messy.
The transmission temperature can be read with a scan tool.
Last edited by rapidoxidation; Dec 6, 2025 at 05:01 PM.
Thread Starter
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From: Milton/Westport, MA USA
me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe; daughter: 2017 GLC SUV
I guess my takeaway is that if my mechanic is not comfortable about knowing the process I should not try to force him.
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MB’s of all kinds.
About to do the service on our 15 ML. FCP Euro has the kit with everything you need. It can be messy. However, if the shop does not feel comfortable then find another shop. It’s not worth them messing things up.
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From: Australia
2014 ML63, 2018 GLC43, 1929 DB victory six sports roadster
I bought a 5L garden sprayer and fitted it with Nitto fittings and the adapter. Pump in about half a litre more than you take out, let it get to 45c and then unplug the nitto fitting and let it drain out until it stops. Pretty easy job to do. Make sure you get new bolts for the pan. I do a drain and fill every 30,000km.
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2013 ML550 US spec. Air+Offroad pkg
Tranny flush W166
Its really not too hard. I did it on my ML550 and to refill, I just poked a hole in the fluid bottle (think it was Pentosin brand from FCP Euro with proper MB spec) ran compressed air to force the fluid up a tube stuck in separate hole in bottlecap to the tranny. Make sure you have the screw-in fill connector that screws into the drain/fill hole, properly place the magnets in the pan before reinstall (mine were in wrong place from factory), and as said above NEW BOLTS. They are designed to stretch when properly torqued and should not be reused once loosened. I drained my torque converter too....rotate engine via socket and ratchet from front crank takeoff till plug shows thru hole on bottom. Mine took 9liters to fill, dealer told me they never drain the torque converter, just oilpan and put 5 liters in and call it good!
Last edited by Leetom; Dec 7, 2025 at 10:07 AM.
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Mercedes SL R231
Ideally, you want to drain the TC as well. However, if the fluid looks good coming out (i.e., not black or smelling burnt), replacing just the fluid in the pan WITH a new filter, so be sufficient, especially if you change your fluid ahead of schedule. Early 7G transmissions did not have a drain plug on the TC. Hmmm, maybe that's why one was added.
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At the very least, OE parts carry a basic quality certification to meet preset standards.
Last edited by CaliBenzDriver; Dec 7, 2025 at 01:31 PM.
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2013 ML350 Bluetec
Brakes? There are aftermarket options that are both far cheaper and far superior.
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Ideally, you want to drain the TC as well. However, if the fluid looks good coming out (i.e., not black or smelling burnt), replacing just the fluid in the pan WITH a new filter, so be sufficient, especially if you change your fluid ahead of schedule. Early 7G transmissions did not have a drain plug on the TC. Hmmm, maybe that's why one was added.
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I'm back! I got my drain and fill done at a non-dealer German car specialist near me, $650 (dealer wanted $863). My daughter needs the same service on her GLC300 in Denver and she was quoted $781.50 for a "725.0 Transmission Power Flush". I told her to inform them that the service is a drain and fill, not a flush, and they responded thusly:
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
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2013 ML550 US spec. Air+Offroad pkg
Just a guess, but a flush may be just hooking lines up to a MOC machine and pumping out old and new in, while a proper drain and refill involves removing the pan and replacing the filter, standpipe, bolts and should clean out the pan sludge too. Honestly, I have trouble trusting anyone to properly/completely do the work, just DIY...isnt really that difficult, just a little messy.
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From: In the Shadow of the Tetons
2013 ML350 Bluetec
A flush is easier: Open up the fluid line between the transmission and cooler, connect the flush machine, and let'r rip until clean fluid comes out the supply line, then reconnect the lines and they're done. I'd bet they'll not take down the pan and change the filter.
The drain and fill is labor intensive AND you get a fresh filter.
IIRC the drain and fill is recommended service. A flush is not so much due to the issue of dislodging crud with the pressures involved, and that leads to shifting issues thanks to that crud getting into places it isn't welcome (solenoids, valve bodies, oil passages, etc).
The drain and fill is labor intensive AND you get a fresh filter.
IIRC the drain and fill is recommended service. A flush is not so much due to the issue of dislodging crud with the pressures involved, and that leads to shifting issues thanks to that crud getting into places it isn't welcome (solenoids, valve bodies, oil passages, etc).
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
I'm back! I got my drain and fill done at a non-dealer German car specialist near me, $650 (dealer wanted $863). My daughter needs the same service on her GLC300 in Denver and she was quoted $781.50 for a "725.0 Transmission Power Flush". I told her to inform them that the service is a drain and fill, not a flush, and they responded thusly:
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
Drain and Fill in MB is a lot more work than power flushing the lines and refill. Wonder how they plan to refill it.
SUMMARY: if the technician is not familiar with these transmissions, RUN. Likely they will use the wrong fluid, fill to the wrong level
Last edited by JCM_MB; Mar 3, 2026 at 02:18 PM.
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2005 E55 AMG
I'm back! I got my drain and fill done at a non-dealer German car specialist near me, $650 (dealer wanted $863). My daughter needs the same service on her GLC300 in Denver and she was quoted $781.50 for a "725.0 Transmission Power Flush". I told her to inform them that the service is a drain and fill, not a flush, and they responded thusly:
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
"Automatic Transmission 725.0 AP27.00-P-2702B $1129.08"
Why would a drain and fill cost more than a flush? She asked but the SA seems to be a little "English-challenged"; we're inclined to go with the flush; thoughts??
FWIW, this non-dealer German car specialist, Star Tech in Denver, wants $371 for spark plug replacement (Dealer $607.78) and $417.50 for front brake pads (Dealer $637.73). For the trans. service the dealer quoted "TFE3 Transmission fluid/filter service @ $1171.67"!!
Last edited by 05-E55; May 10, 2026 at 02:08 AM.
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2013 ML550 US spec. Air+Offroad pkg
Drain/flush
A flush just hooks lines up to a pump and they pump out old fluid and new goes in. A drain and fill (done properly) pulls the pan, replaces the filter, cleans the pickup magnets and pan, puts in a new fluid dam, all new pan bolts (one time use stretch bolts) and if you are lucky, they will also drain the torque converter and replace the crush washer.
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From: Ottawa, Ontario
2013 GLK350 Canada
Ok folks, all good for the gas engines. Is there any difference for the diesel models (recently acquired, unknown history, Canadian 2015 ML350 4Matic with airmatic suspension)?
Best,
Steve
Best,
Steve
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2005 E55 AMG
A flush just hooks lines up to a pump and they pump out old fluid and new goes in. A drain and fill (done properly) pulls the pan, replaces the filter, cleans the pickup magnets and pan, puts in a new fluid dam, all new pan bolts (one time use stretch bolts) and if you are lucky, they will also drain the torque converter and replace the crush washer.
