Gearbox leak on Tiptronic ML-270

[Mark A]

I had my ML-270 in for a service about 3/4 weeks ago, and as I had 70K on the clock, I asked for the autobox oil to be changed. Pretty much as soon as I got the car back, I noticed that the engine over revved before changing into 3rd but I was hoping it would settle down after a few days. It didn't.

I had to take the car in for MOT and asked him to check the level, as previous posts suggested that a low level may be the problem. It now looks as if I have a leak, as almost 1L had to go in. The car is going back in on Monday for investigation, what is the most likely cause of the problem. I have seen gearbox guide bushing and corroded cooler pipes being mentioned, but what is most likely ??

Never had a gearbox leak before the oil change, is it possible that the seal has been nipped ??

Cheers,
Mark

 

[jberks]

Are you sure you have a leak?
1l would make a hell of a mess.
More likely they didn't put enough in at the time. I imagine it can be tricky to gauge as the torque converter isn't officially drainable so if some does come out it could alter the level on fill up.
I'll watch out myself - going to collect mine this afternoon and thats one of the things they've done allegedly.

 

[greenfingers]

Perhaps they checked the level without going through the gears, which would prevent the fluid from filling all the cavities - hence they got a full reading when the box was not full?

 

[Ellsy Tanners]

I agree with jberks, a low level will cause slipping as you described. Was the garage a merc dealer or specialist, as a special dipstick is used to check the oil level and it must be above 80 degrees.
I think is about 4 litres of oil to but in after a filter change.
if you do have a leak then a incorrectly fitted gasket or seal would seem propably as you have just had a change.

 

[Mark A]

I took all of the plastic undertrays off last night and the bottom of the gearbox casing is very wet with oil. It looks as if it is coming from a bit higher up, the garage was an independent, and he does have the dipstick as he has done this type of gearbox before.

I was just wondering if he over filled it (no way to prove unfortunately) what would most likely go first. Is is possible that it is leaking from the filler / where dipstick was used ??

The garage says it could be the the gasket between the gearbox and torque convertor, but I'm not convinced. It is booked in for an other look on Thursday, I just hope that it stays together long enough to get the wife there (12 miles).

Cheers,
Mark

 

[greenfingers]

Someone posted on here a while ago about a leaking O'ring where the dipstick tube enters the gearbox casting. IIRC, it was a cheap and easy fix - and I'm sure he documented it with photos etc.

The sump gasket is a thick rubber job, and would have to be very badly fitted to leak - Of course you eliminate that if the mess is evident any higher.

 

[jberks]

Mine had leaked apparently around the electrical plug. The dealer has fitted a new seal (FOC/warranty) but this in extreme cases can cause damage to the ECU so well worth checking.

 

[Mark A]

Just heard back from the garage, and he seems to think that it is the gasket between the gearbox and torque convertor. Has this ever happened to anyone else, and any ideas how much to sort. I'm being told it's a gearbox out and send it to an AT specialist to split and change the gasket. Sounds FE :cry::cry:

Mark

 

[BlackC55]

5 hours labour for the box R&R.

You dont need a specialist. Its only a few bolts and the bell housing comes off.
Are you sure its not the torque converter seal? If it is any competant mechanic can fit a new seal.

 

[BlackC55]

double post

 

[BlackC55]

5 hours labour for the box R&R.

You dont need a specialist. Its only a few bolts and the bell housing comes off.
Are you sure its not the torque converter seal? If it is any competant mechanic can fit a new seal.

 

[greenfingers]

I would check that the bolts are tight first.

The garage option does sound FE, so maybe it's worth trying to loosen it off a bit and then squeeze in some of that liquid gasket stuff to see if that works - I'm waiting for the abuse, but it is only low pressure/temp right?

Having said that, I wouldn't want to risk a long journey if it increased the chance of a £4000 bill for a recon autobox!

 

[Mark A]

The garage have now come back saying that the leak looks as if it could be coming from the 13 pin plug connection. Any ideas how to repair ??

 

[BlackC55]

Needs a new pilot bushing. VERY VERY common. Dealers stock loads of them. Give your local a call. Cheap too!

 

[Mark A]

Many thanks.

My garage has the bushing but is still waiting for the info from his mate in the local MB dealer as to how to change it. Does anyone have instructions preferrably with pictures.

You mentiona a special tool. Can I just buy this from the MB garage ?? Do you have a part number by any chance (or am I pushing my luck !!).

Cheers,
Mark

 

[jberks]

Dont know how to change it, but he dealer did mine 2 weeks ago - don't know the cost as it's warranty). Very common fault it seems.

 

[panason1c]

Many thanks.

My garage has the bushing but is still waiting for the info from his mate in the local MB dealer as to how to change it. Does anyone have instructions preferrably with pictures.

You mentiona a special tool. Can I just buy this from the MB garage ?? Do you have a part number by any chance (or am I pushing my luck !!).

Cheers,
Mark

A very quick and easy job to do....No special tools required....about 15 minutes from memory.

Rotate the locking ring (that is built into the electrical plug) anticlockwise and remove the plug....

Using a 1/4" drive and extension remove the small bolt ( 8mm, i think) that is located deep in the centre of the bushing and then pull out the bushing from the gearbox......(there will only be a very small loss of atf at this point)

Re-assemble using the new bushing that comes complete with new '0' rings...........Note...Do NOT overtighten the small centre bolt...just a 'nip' is sufficient.

Finally, check the atf level and top-up.

 

[panason1c]

maybe it's worth trying to loosen it off a bit and then squeeze in some of that liquid gasket stuff to see if that works

Liquid gasket and auto-gearboxes shouldn't be mentioned in the same sentence, in my opinion............any 'wayward blobs' of liquid gasket that found there way into the valve block, etc, would cause very serious and expensive problems.

 

[BlackC55]

(7mm bolt)

When the bushing is removed some atf will gush out.

I am amazed that the garage you use cant work out how to change it. It is very simple.

Next time take it to a specialist or someone competant to work on your car.