Weird automatic gearbox issue

hod05

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E 250 cabriolet, 190E 2.0L
2010 E250 with 5 speed autobox

Pulls fine, acceleration fine, kickdown works all gears seem to work fine the issue is occasionally when driving down hill or flat the revs drop to idle exactly like a manual car with clutch down.

I always assumed slipping trans meant the revs would rise whilst the car fail to accelerate the acceleration and pull is fine it just seems to coast occasionally.

Going to replace fluid and filters first since this was last done about 3 years ago done about 20k miles since. car had done 105k miles. Hope the box ain't about to blow
 
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Wighty

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2010 E250 with 5 speed autobox

Pulls fine, acceleration fine, kickdown works all gears seem to work fine the issue is occasionally when driving down hill or flat the revs drop to idle exactly like a manual car with clutch down.

I always assumed slipping trans meant the revs would rise whilst the car fail to accelerate the acceleration and pull is fine it just seems to coast occasionally.

Going to replace fluid and filters first since this was last done about 3 years ago done about 20k miles since. car had 105k miles. Hope the box ain't about to blow
Might be worth checking the ATF level first , so you have an idea if maybe low fluid is causing the issues ?
Check it hot , on level surface , engine running with engine in Park (assuming you have a dispstick to use , they are a few quid on eBay ) .
Low oil levels can throw up gearbox problems .
 
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hod05

hod05

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Might be worth checking the ATF level first , so you have an idea if maybe low fluid is causing the issues ?
Check it hot , on level surface , engine running with engine in Park (assuming you have a dispstick to use , they are a few quid on eBay ) .
Low oil levels can throw up gearbox problems .

Ok thanks I didn't realize the car dosn't come with a dipstick for gearbox already in it.

I'm not actually sure how to check the level? I can see the engine I'll dipstick but don't knkw where the ATF one is located
 

Wighty

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image.jpeg
Ok thanks I didn't realize the car dosn't come with a dipstick for gearbox already in it.

I'm not actually sure how to check the level? I can see the engine I'll dipstick but don't knkw where the ATF one is located
This is from my 5 geared CLK
 
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hod05

hod05

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View attachment 50204
This is from my 5 geared CLK
Thanks for this I Found where it is in just need a dipstick to check it.

Looking underneath the car there is a black wet patch on the plastic under pan right about underneath where the gear selector is.

Pretty worried now that this is the fluid leaking though I've never found any stains on the drive.

The last couple of times I've driven I've notice the fan on quite alot but the temp gauge had always been normal. hope I've not cooked the gearbox.
 

Jim2

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hod05

hod05

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Do mercs have a warning light for overheating transmission?

Would you expect some kind of limp home mode or CEL to come on if the transmission was getting too hot?

Or would the car drive with minimal signs until it just blew up?
 

Flyinspanner

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Get some kitchen towel, or a clean whiteish rag, dab that damp patch, if it’s reddish residue, you may have an ATF weep/leak.

If it’s brown/black, it’s oil from elsewhere on the engine.

You can buy a gearbox dipstick on eBay/amazon, and lookup how many cm up the stick is ‘normal level’ for your model. Think they are under £10.

When you dip it, the red plastic tag on the dipstick cover will ping off, DONT worry it’s not required, but try to avoid it going into the tube!
 
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hod05

hod05

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Get some kitchen towel, or a clean whiteish rag, dab that damp patch, if it’s reddish residue, you may have an ATF weep/leak.

If it’s brown/black, it’s oil from elsewhere on the engine.

You can buy a gearbox dipstick on eBay/amazon, and lookup how many cm up the stick is ‘normal level’ for your model. Think they are under £10.

When you dip it, the red plastic tag on the dipstick cover will ping off, DONT worry it’s not required, but try to avoid it going into the tube!

I've just done this the fluid is similar in colour to the engine oil. I'm worried that it is indeed ATF and that the trans overheat and burn the fluid black.

The car drove fine apart from subtle signs no warning lights or limp mode ever came on.

Would overheating trans or low fluid trigger limp mode or warning light?

I started the car up and shifted between P N D R and it shifts smooth with no clunks or delay. Hopefully this is a sign the box isn't knackard
 

kid-jensen

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A change of fluid is the only "cheap" work you can do on an auto, after that, everything gets expensive.

So in your case, it might be worth doing a complete flush if the fluid is not red...

And keep your fingers crossed.
 
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hod05

hod05

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A change of fluid is the only "cheap" work you can do on an auto, after that, everything gets expensive.

So in your case, it might be worth doing a complete flush if the fluid is not red...

And keep your fingers crossed.

Right I know that but wouldn't the car have gone into limp mode of the trans got too hot?
 
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hod05

hod05

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So do E class have a gearbox oil temp sensor? Or Fluid level sensor?

Would lie fluid cause warning light/limp mode or service message?

Would an autobox getting too hot result in limp mode and/or warning light?

Or will it let you unwittingly keep driving with low fluid level and overheating box until it's cooked?

Does Anyone have an answer on this?
 
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LostKiwi

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No MBs have low fluid warning as far as I know. There is a temperature sensor on the conductor plate.
None of the symptoms you describe suggest a failed or failing gearbox.
If you want to be sure get it on Star and look at fill times and adaptations.
Star can read a lot of information about the state of the gearbox.
 

Oldspanners

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So do E class have a gearbox oil temp sensor? Or Fluid level sensor?

Would lie fluid cause warning light/limp mode or service message?

Would an autobox getting too hot result in limp mode and/or warning light?

Or will it let you unwittingly keep driving with low fluid level and overheating box until it's cooked?

Does Anyone have an answer on this?
You may have some intermittent engine problem rather than a gearbox problem as if the level gets too low you certainly will have problems all the time. Have you had a code reader on to see if there are any stored codes?
What type and model of engine is in your car? As various models have a small engine oil leak at the rear which will eventually collect at the bottom of the bell housing.
 
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hod05

hod05

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No MBs have low fluid warning as far as I know. There is a temperature sensor on the conductor plate.
None of the symptoms you describe suggest a failed or failing gearbox.
If you want to be sure get it on Star and look at fill times and adaptations.
Star can read a lot of information about the state of the gearbox.

Ok can't have overheated then since no warning ever came in and it never went into limp mode either.

What could cause the revs to drop to idle whilst at speed like coasting a manual? Gearbox slipping?

No slipping on acceleration though
 
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hod05

hod05

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You may have some intermittent engine problem rather than a gearbox problem as if the level gets too low you certainly will have problems all the time. Have you had a code reader on to see if there are any stored codes?
What type and model of engine is in your car? As various models have a small engine oil leak at the rear which will eventually collect at the bottom of the bell housing.


Engine is the E250 CDI om651 the leaking fluid looks black like engine oil.

I'm only thinking about the gearbox because the revs drop to idle like it's coasting (slipping?) But works fine on acceleration. Which is why I'm Confused.

It's booked In to be looked at. Will be getting the box fluid/filter done as well
 
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hod05

hod05

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How long have you had the car?

Around 5 years. Why? I have FSH Always serviced correctly and gearbox oil done every 30k roughly chain tensioner replaced about 35k ago due to leaking so doubt it's that again
 

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