Full/Partial flush ATF
Thread Starter
Senior Member
Joined: Feb 2015
Posts: 434
Likes: 16
From: Midlands, UK
CLK W209
Full/Partial flush ATF
Hi guys,
So my latest CLK, a December '06, has an auto 722.6 transmission.
In the service schedule it recommended flushing ONCE at 39,000miles.
Though I know that it is now recommended /40,000 miles.
It got a flush at 37,500. However there is nothing in the service history now to suggest that it had another one at ~80,000; and the car is now on 120,000 miles.
So it is due its third, but I can only be sure it has had one.
Being my first auto, and only my second car at my age and experience, I am unsure whether the changes occur as they should be, sometimes I can feel a downshift, and I'm not sure whether this is normal, as the majority of the time, it's smooth enough to iron out the ratios.
I am unsure whether to just do the usual partial fluid change procedure of a few litres, or go all out and do the full flush.
I'm tempted to go for a full flush myself.
Now I can get 5L for £38/$55, or I can get a 20L drum for £100/$145.
I know a full flush requires about 14L, which I could achieve with 3x 5L bottles, or for less money, I could get 20L, leaving me with 5-6L surplus, and having to store, however that would be sufficient to hold on to for another partial flush. Though I don't fancy having to store that fluid for the 4 years it is going to take for me to run up to another interval.
So I wonder what your thoughts are? Do I do a whole or partial flush? Do I just use the whole 20L in one flush? Or do I keep the remaining 6L and do another partial after 6 months or so..? Would there be any benefit to that?
TIA,
Ben
So my latest CLK, a December '06, has an auto 722.6 transmission.
In the service schedule it recommended flushing ONCE at 39,000miles.
Though I know that it is now recommended /40,000 miles.
It got a flush at 37,500. However there is nothing in the service history now to suggest that it had another one at ~80,000; and the car is now on 120,000 miles.
So it is due its third, but I can only be sure it has had one.
Being my first auto, and only my second car at my age and experience, I am unsure whether the changes occur as they should be, sometimes I can feel a downshift, and I'm not sure whether this is normal, as the majority of the time, it's smooth enough to iron out the ratios.
I am unsure whether to just do the usual partial fluid change procedure of a few litres, or go all out and do the full flush.
I'm tempted to go for a full flush myself.
Now I can get 5L for £38/$55, or I can get a 20L drum for £100/$145.
I know a full flush requires about 14L, which I could achieve with 3x 5L bottles, or for less money, I could get 20L, leaving me with 5-6L surplus, and having to store, however that would be sufficient to hold on to for another partial flush. Though I don't fancy having to store that fluid for the 4 years it is going to take for me to run up to another interval.
So I wonder what your thoughts are? Do I do a whole or partial flush? Do I just use the whole 20L in one flush? Or do I keep the remaining 6L and do another partial after 6 months or so..? Would there be any benefit to that?
TIA,
Ben
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Since you are in the UK, you say "2006" but that's probably the "plate year" and not the "model year". By MY2006, all cars had the 722.9 7-speed transmission. If you have the 722.6 5-speed, then you have a MY2005 V6 or I4 (the V8 CLK500 would have had the 7-speed for MY2005).
Anyhow, if you have the 722.6, it's not as critical to do a transmission flush as with the 722.9. My advice would be to get the 5l of fluid, a filter and a pan gasket. Drain the pan, drop it, replace the filter, then refill with the 4-5l required to top it off to the proper level. The exception to that would be if you have had any specific problems, such as the defective Behr radiator that mixed coolant and transmission fluid. In that case, I'd do a flush.
Anyhow, if you have the 722.6, it's not as critical to do a transmission flush as with the 722.9. My advice would be to get the 5l of fluid, a filter and a pan gasket. Drain the pan, drop it, replace the filter, then refill with the 4-5l required to top it off to the proper level. The exception to that would be if you have had any specific problems, such as the defective Behr radiator that mixed coolant and transmission fluid. In that case, I'd do a flush.
Senior Member
Joined: Dec 2014
Posts: 391
Likes: 14
From: Orlando, FL
05 CLK55 AMG (1 of 247) Cubanitsilber designo series
I would drop the pan, do a filter change, clean the pan and the magnet and replace the gasket. Do the normal fill, around 5 liters. Drive the car for a week and do a drain and fill, another 5 liters. If the drained AFT still looks brown, repeat.
Thread Starter
Senior Member
Joined: Feb 2015
Posts: 434
Likes: 16
From: Midlands, UK
CLK W209
Hi,
So the manufacture date was April 2006, and it was registered December 2006. Which btw, is a 56-plate in the UK.
I also was confused, since in retro view I do not know why my car has a 722.6 and not a 722.9 fitted. Maybe it was a diesel thing to phase out the boxes, I do not know.
So you would not think it necessary to flush the whole box out completely, having missed a change already?
If not that makes my job easier, since I can get a genuine Mercedes gearbox service kit for about £80/$115 with everything I need. Saves me having to buy the parts individually.
Why do you suggest a partial and not a full change? Is it due to the a lack of need?
Could a full flush actually be malificent in any way?
So the manufacture date was April 2006, and it was registered December 2006. Which btw, is a 56-plate in the UK.
I also was confused, since in retro view I do not know why my car has a 722.6 and not a 722.9 fitted. Maybe it was a diesel thing to phase out the boxes, I do not know.
So you would not think it necessary to flush the whole box out completely, having missed a change already?
If not that makes my job easier, since I can get a genuine Mercedes gearbox service kit for about £80/$115 with everything I need. Saves me having to buy the parts individually.
Why do you suggest a partial and not a full change? Is it due to the a lack of need?
Could a full flush actually be malificent in any way?
Senior Member
Joined: Dec 2014
Posts: 391
Likes: 14
From: Orlando, FL
05 CLK55 AMG (1 of 247) Cubanitsilber designo series
There is no drain on the torque converter, so to do a total flush you have to disconnect the output hose to the transmission cooler, run the engine to pump out the old fluid while someone pours new fluid at the same rate into the transmission from the filler pipe in the engine compartment. IMO Mercedes transmissions are so sensitive to having the exact correct level of fluid, it's not worth creating a low fluid condition while the engine is running. Also, whether you are doing a full flush or a partial fill and drain several times, you are mixing new fluid with old fluid.
Thread Starter
Senior Member
Joined: Feb 2015
Posts: 434
Likes: 16
From: Midlands, UK
CLK W209
That is correct. So what would consensus be on doing a partial driving it for say 20 miles, fair amount of shifting and then do another...?
Would there be a need to replace the gasket once again? Or perhaps I could just jack up the rear end and run the transmission that way, and just put the old gasket on and keep the old filter in for that period..?
Would there be a need to replace the gasket once again? Or perhaps I could just jack up the rear end and run the transmission that way, and just put the old gasket on and keep the old filter in for that period..?
Senior Member
Joined: Dec 2014
Posts: 391
Likes: 14
From: Orlando, FL
05 CLK55 AMG (1 of 247) Cubanitsilber designo series
You wouldn't need to drop the pan a second time. Just drain the fluid and refill. I would definitely not jack up the rear and run the car in gear. Just drive it for a bit circulate the fluid.
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Thread Starter
Senior Member
Joined: Feb 2015
Posts: 434
Likes: 16
From: Midlands, UK
CLK W209
Ah so there's a drain plug and a pan, I've not had a look underneath myself yet. I had imagined just draining by dropping the pan, since they were 'sealed for life'.
Once I'm back from uni for the Easter break I shall look at my work rota and see when I can do it, hopefully within the next fortnight.
I might also do the differential oil whilst I'm at it, then it's pretty much new fluid all around since I bought it in December, PAS full flush, brake fluid, coolant, engine oil. Just the ATF and diff to do.
Fluid changes are quite satisfactory, seeing all that dirty gunk come out and putting fresh in.
Once I'm back from uni for the Easter break I shall look at my work rota and see when I can do it, hopefully within the next fortnight.
I might also do the differential oil whilst I'm at it, then it's pretty much new fluid all around since I bought it in December, PAS full flush, brake fluid, coolant, engine oil. Just the ATF and diff to do.
Fluid changes are quite satisfactory, seeing all that dirty gunk come out and putting fresh in.
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Thread Starter
Senior Member
Joined: Feb 2015
Posts: 434
Likes: 16
From: Midlands, UK
CLK W209
Yes, I've that WIS saved from my copy on my iPad too, for when the time could have come.
And because it is so simple, is why I am unsure whether I should just go the whole hog and do a full flush..?
And because it is so simple, is why I am unsure whether I should just go the whole hog and do a full flush..?
