Torque converter draining.

[DVA1]

I’ve tried looking under different headings and found various schools of thought regarding the draining of the torque converter when doing a transmission flush on my 98 C280

My issue is that at some point someone has attempted to remove the drain plug, only to snap the torx bit (assuming that’s what they’ve used) rendering the drain plug unusable. There is also some kind of hard putty/epoxy around the plug. I’ve tried drilling it out but it looks like the bit stuck in there is impervious to drill bits.
Luckily there has been no leaks. However, without the use of the drain plug I’ve found 2 options of draining the torque converter.

1. Find the lower coolant hose, turn the engine on and allow about 2 litres to flow out of the coolant hose and then replacing it with 2 litres, doing this until the fluid expelled is pink/red. However this makes no sense to me, as I thought the coolant hose is for coolant.
If there is another hose for the fluid in the torque converter where would I find it?

2. Fill the transmission up as normal with the correct amount of fluid. Drive the car for about 100 miles and then do a complete flush again, thus replacing the mixed clean and dirty fluid with clean fluid. The question here is how much fluid should be going back in?

Unfortunately I didn’t measure the correct amount of fluid that came out because the container already had stuff in it.

So far everything else has been plain sailing, whoever has tried to do a transmission flush has over-torqued the bolts holding the transmission pan to the housing, not replaced the red clip and probably overfilled the transmission judging by the amount that came out. (It looked like a lot.) But the car has been running fine.

So I’m doing this as a preventative measure.

Any advice or pointers would be greatly appreciated

D

 

[Bellow]

How I did my (non MB).
Perform all actions as per changing only the fluid in the pan ie, up to the point where the pan is refitted and the level roughly where it should be. Then, remove the return line from the cooler and arrange for the cooler to drain into a receptacle (ie, stick a length of hose on the fitting). Start the engine and the fresh oil added will displace the fluid in the TC. If flow ceases before required cleanliness of emerging fluid is attained stop engine and replenish pan. With this done, reconnect disconnected hose and top up oil to required level using dipstick.

 

[DVA1]

How I did my (non MB).
Perform all actions as per changing only the fluid in the pan ie, up to the point where the pan is refitted and the level roughly where it should be. Then, remove the return line from the cooler and arrange for the cooler to drain into a receptacle (ie, stick a length of hose on the fitting). Start the engine and the fresh oil added will displace the fluid in the TC. If flow ceases before required cleanliness of emerging fluid is attained stop engine and replenish pan. With this done, reconnect disconnected hose and top up oil to required level using dipstick.

Thank you. You wouldn’t happen to know which one is the cooler line? I’ve only got Nemigaparts as a reference and it’s not all that clear.

 

[optimusprime]

Jist drain and replace the filter . Do this and run the car for 3 weeks ...Drain off again and refill it again replacing the filter .For sure do it a few more times .

 

[Bellow]

Thank you. You wouldn’t happen to know which one is the cooler line? I’ve only got Nemigaparts as a reference and it’s not all that clear.

Nope, no idea which is which!
If you can trace the lines back to the gearbox, the out line to the cooler is probably forward of the return line. But, it doesn't matter too much. If you get lucky and get the return line fine. If not, the same procedure applies but you wont have flushed the cooler but it can be (gravity) drained by disconnecting its other line.

 

[W1ghty]

Every year on my 5g gearbox , I just Pela 6000 suction the ATF out via the dipstick tube (when hot) then add clean ATF by the same tube .
£30 for 4L of Fuchs ATF ish .
I couldn’t tell if the sump filter had been changed ? …Every 35-40 k if not

 

[optimusprime]

But that wont remve old fluid from the totque converter ,,, only from the sump . But three, or four, of these removals with the use of an extractor pump , will be fine . Half the time most workshops dont even drain the converter . And new models dont even have a drain plug to drain off the old fluid .

 

[Trickythemerc]

Introducing clean fluid into the box can only be a good thing to do. My box had the works at 80K now on 124K and all the bits on the shelf to do a full works job early next year.

 

[W1ghty]

But that wont remve old fluid from the totque converter ,,, only from the sump . But three, or four, of these removals with the use of an extractor pump , will be fine . Half the time most workshops dont even drain the converter . And new models dont even have a drain plug to drain off the old fluid .

It won’t as you say remove it from the TC but I do this every year just to introduce 50% of new clean ATF (I still change the filter every 30-40k) .
It is a quick easy cheap job as far as maintenance goes

 

[DVA1]

It won’t as you say remove it from the TC but I do this every year just to introduce 50% of new clean ATF (I still change the filter every 30-40k) .
It is a quick easy cheap job as far as maintenance goes

Sounds like a good plan. Mine is only on 68k so it’s probably a good idea to do this while doing a regular oil change.
Thank you