Numair Aidroos

I've recently clocked 97,000 KM, and at 60000 KM the transmission was flushed clean. Now the dealership is recommending to change the transmission filter and drain the torque converter as well. My question is where is the drain bolt located? Reason I ask is because some forum members claimed its behind the rubber window, whole others stated it needs to be drained from the converter while the engine is running. If there is a drain bolt I'll know not to be fooled in to paying the dealership what they have quoted. And on a side note our transmission rebuilder asked us to refill with zf 6 lifeguard, instead of the zf 7.2 Lifeguard (MB 236.15). I've checked the chemical properties and it backs one of his theory of the flash point being at 230 deg celcius on zf 6 V 206 deg celcius on zf 7.2, so the viscosity differs a point where zf 6 is thicker at operating temperature. He refurbished 100s of MB transmissions so I trust his instinct.
*Has anyone tried MB 236. 15 from Mannol? Or their 800K mile range getriebeol for the limited slim differential? Please recommend any transmission fluid apart from ZF and any diff fluid. I've liked ZF, but they are not fully synthetic.

**Anyone with transmission code knowledge, does this transmission have a drain bolt/plug on the torque converter?

BOTUS

drain out 7 litres fill with 7 litres go for 10 to 20 mile drive, drain part dirty fluid, take off the sump clean the 6 solenoid gauze filters, replace main trans filter refill and check level when at 80C

Numair Aidroos

Thank you. This makes sense, with or without the drain bolt. So in total I need to pay for 15 liter fluid. Which fluid do you recommend for the transmission 7.2 or 6 from ZF, and what about the fluid for the Limited Slip differential?

chassis

What does “flushed clean” mean? Where (who) did you have the 60k km service done?

Use MB specified fluids. Search the Bevo site and this one, this topic is extensively covered.

Numair Aidroos

Conductor plate, and filter replaced. ZF 7.2 filled, billed for 9 liter. All at the local dealer. By answering any of your questions, where does that help me find the tq converter drain bolt? Or even decide between zf 6's higher flash point temp or even a pick a new synthetic 75w90 fluid for the LS Diff?

BenzNinja

iTrader: (4)

Numair Aidroos

Thank you @BenzNinja ,but is this drain bolt available on the 722.90202? Please advice.

BenzNinja

iTrader: (4)

THIS IS BASED ON YOUR VIN

artim808

I always flush the fluid. Disconnect the atf return pipe from radiator. This way you can be assured that all fluid from system is replaced with fresh one. This include the fluid in torque converter, radiator, etc...

Numair Aidroos

Thanks, this drain bolt will make the job easier. I appreciate your input.

Numair Aidroos

Thank you, your method should do well, in case they cant locate the drain bolt via engine rotation. Approximately How much ZF fluid would be needed? The dealers love to charge extra here.

BOTUS

lots of places for fluid to hang about you can't get it all out

all these are estimates in litres

The TC 2.5
The pump 0.5
The filter area 0.5
Valve body and solenoids 0.5
Pipe and the trans cooler in the rad 1.5
General gearbox and clutch components 1.0

so no matter how you try will be min of 1 litre of filth and probably 2 to 3 litre around the box and cooler. So vs a sump off filter and TC drain - you'd be far better off drain fill drive and do again, This way fresh fluid got in all the oil ways and clutch packs.

The early W221 7G boxes takes 236.14 - fuchs version = TITAN ATF 4134
Ultra High Performance ATF, specially developed to optimize shifting performance of Mercedes-Benz automatic transmissions. Product dyeing: red.

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The later 7G boxes take 236.15 - fuchs version = TITAN ATF 7134 FE
Premium Performance ATF with reduced viscosity, especially developed to further optimize fuel-economy and gearbox efficiency of latest generation Mercedes-Benz 7-speed automatic transmissions. Not downwards compatible with previous MB-ATF-Specifications. Product dyeing: blue.

BOTUS

and the filter in the sump?

there is a equipment about that allows this type of on the fly fluid change, but if they then don't do the filter its dangerous, as the filter will be blocked and the box will die, And if you do the filter first surely you then pump half the filth blocking the new filter ?
I can't see a better way then to drain fill, drive, drain, filter swap and fill...


https://www.vehicleservicepros.com/d...uid-exchangers

artim808

I always replace the filter first, clean the magnets and fill oil pan with fresh fluid. Then I disconnect pipe from radiator and start flushing until new fluid is coming from the pipe. And of course check the level with STAR connected at proper temperature according to WIS. Usually I use 12 liters of fluid. This way I have fresh fluid in whole system. I don't like when the new fluid is mixed with old one.

Numair Aidroos

Thank you, I'll do the same. Indeed, this God willing makes less effort to keep the clean oil in and used oil out.