ATF colour ?

[alf1956]

Hello fellow members
I have a clk270 cdi 55 plate auto & I have checked the atf fluid which is at the correct level but the fluid is a light brownish colour is this normal? I have an intermittent gearbox fault where as every now & then it wont change up into top gear so I was wondering if this was atf related?

 

[daveenty]

Fluid should ideally be a reddish colour with a "sweet" smell. Sounds like yours is a bit burnt/used. Does it have a burnt smell to it?

You don't mention mileage. The consensus nowadays seems to be to change the oil at around 40,000 miles, which I agree with and try to do on my own cars.

Do you have any record of it ever being changed? If not, this should be the first step and may help with your other issue...

 

[whitenemesis]

When was the fluid and filter last changed? Light brown isn't bad, atf is red when fresh.

 

[grober]

Colour is not so important as opacity[ how "transparent " the gearbox fluid is ] which is a reflection of how much gum/particulate matter is entrained in it because that's what blocks all the valving in the control hydraulics in what is known as the gearbox " conductor plate* +valve body assembly " Failure to select a gear may be due an intermittant blockage in this unit or an electrical failure. There is a plug which allows the car to communicate with the gear box and sometimes the plug seal can leak allowing the connection to be contaminated. First thing as daveenty and whitenemesis suggest is to change the gearbox fluid and filter. If problems persist it could be fluid contamination of the plug or a conductor plate/valve body problem.
ps if you do a search on YouTube for Mercedes conductor plate* you will get a better visual explanation

 

[alf1956]

Thank you for your replies, it does not smell burnt but is not the cherry colour, it has never had an a atf change & has 130k on the clock, i am not sure which bos is in it as it does not show the gear its in on the dash as some Mercs do it just shows P D N R

 

[a111r]

Take it to a good Indy with STAR.
If a conductor plate is needed, which is quite common, it's much more cost effective to have it done within an ATF and filter change, whilst the gbox sump is off.

I've always found ATF134 does not stay cherry for long, not surprising really, as all my cars were on their original fluid, 130 to 190K miles.

 

[alf1956]

Today I was driving & the car would not change up into top gear so I tried a few experiments, I tried to manually change gear by knocking the gear lever over but it didn't change gear, then I tried to change the mode from C to S again no joy then moved the gear into neutral & then back into drive & it went straight into a low gear & would not change up at all so I pulled in & turned the car off & started it & drove off with it changing up & down the box no problems. I have had it not changing up & I have stopped & turned it off & started it again & it goes back to driving perfectly normal. I t will go for days without a problem then out of the blue it will not change up to top gear so I am wondering why when I turn it on & off it runs perfect so could it be electronic & when you turn it on & off it re-sets itself?

 

[whitenemesis]

Exactly that, cycling the IGN will reset the electroplate error (usually it's the speed sensor on the 'plate that begins to fail). Mine went fine for months before going again. The Mobilo tech said it could last for years, or it could fail completely tomorrow!
I had the pate changed and atf and filter changed and the box was silky smooth and faultless again..

 

[alf1956]

Hello fellow members, I have had my car on a diagnostic machine & was told it is fault code P2206 which is probably the plate in the bottom of the gearbox & I was quoted £600 to do this so I am thinking of taking the gamble on a 2nd box at £250+fitting which I have been told is approx. 2 hours labour. My gearbox is the 5 speed 722.6 & I have been looking around & see that the 722.6 box was fitted to quite a few different models & will they all fit my car with them being a 722.6 box?











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[grober]

Buying a second hand auto box is a bit of a gamble. With the 722.6 box its probably the conductor plate. Its a very common fault. So common there are repair kits for the purpose. If your repair at £600 includes a gearbox fluid gasket and filter change it seems a good price-- the repair can be done without removing the gearbox from the car so less disruptive. see the folowing video for what's involved.
ps not all 722.6 boxes will have the same internal gear ratios but would probably fit

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[amazighman]

Like said above, it might be the conductor plate, get a new one and do it yourself , it is not that big job, just watch few diys online and save yourself £££

 

[alf1956]

Hello fellow members, I took my Clk 270 cdi to Europa cars an Indie garage in Sheffield where I am from as my Grandson works there & he put it on the Star diagnostic computer & he cleared lots of faults but it still showed up a gearbox fault so I drove off on my way home & a soon as I hit the open road the gearbox was changing up & down a smooth as silk & kept like that all day but later in the day after around 20 miles it made a jerking similar to if you let the clutch out too quick in a manual car & it was then a bit intermittent with its gear changing. It has already had a fluid & filter change. Any thoughts on this ? ​

 

[whitenemesis]

Fluid level too low..
Conductor plate failing ..

 

[Flyinspanner]

Shop around indies...
I think that price could be bettered. . .

 

[grober]

An auto transmission contains several multiplate clutch packs and possibly brake bands that are hydraulically operated in order to lock up certain gear combinations to yield a variety of gear ratios. It sounds as if one or more of these is acting intermittently to give your symptoms. As already stated this would arise due to lack of fluid or possibly due to a failure of the valves in the conductor plate to supply adequate hydraulic pressure to the clutch packs.

 

[alf1956]

It has had a new gearbox filter along with new atf fluid less than 100 miles ago which was done to see if that was the problem, drove it this morning for around 3 miles & it was sweet as a nut changing gear lovely !

 

[whitenemesis]

drove it this morning for around 3 miles & it was sweet as a nut changing gear lovely !

Seems you've been here before...

I hit the open road the gearbox was changing up & down a smooth as silk & kept like that all day but later in the day after around 20 miles it made a jerking similar to if you let the clutch out too quick in a manual car & it was then a bit intermittent with its gear changing.

Get the codes read again, see what's come back and current. A failing conductor plate can go on being intermittently faulty then ok for years, or just weeks before failing completely, leaving the car in limp mode or worse still, no gears at all...

 

[exvolvoman]

I would rather get the original box fixed instead of fitting a s/h unit which may have the same faults...or worse

 

[GaugeBoson]

I would echo that the conductor plate is a likely candidate if a fresh read of the codes back that up. A week after buying my E280 with about 87,000 miles on, my car got stuck in 2nd gear as a limp home 'feature'; stopping, turning the engine off and restarting reset the limp feature and I was off again. When an indy with STAR checked, the fault code had been triggered 100's of times, so the previous owner had to know that there was a problem!

With a new conductor plate fitted the gearbox changed cogs so much more smoothly than it had for that first week. I had to provide all sorts of documentation for proof of ownership, home address etc. so that the indy could get a code string from MB; apparently the conductor plate forms part of the security system for the vehicle?!