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Billy, Trainer/ Master Technician
Category: Mercedes
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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I have a 2005 Mercedes Benz CL 600. In Feb 2013 it broke down;

Customer Question

I have a 2005 Mercedes Benz CL 600. In Feb 2013 it broke down; engine warning light came on, there was a puddle of oil under the car and a fair amount of smoke coming from under the car. It was recovered (the technician drove the car onto the recovery vehicle) and taken to Mercedes Benz Brentford.
Subsequent investigation by Mercedes Benz Brentford revealed that a gearbox oil seal, fitted by them in August 2012 had 'blown'. The repair of the oil seal was covered under warranty. When they fitted the new seal and test drove the car the gearbox was not working properly. Further investigation revealed metal pieces in the gearbox sump - net result I had to buy and have them fit a new gearbox at a cost of £8,300!.
My thoughts at the time which I communicated to Mercedes were that the gearbox broke because of a lack of oil caused by the seal failing, especially since the gearbox was working fine until that point (in fact on an unrelated matter Mercedes Benz Brentford had the car in for repairs to the suspension just 3 weeks prior and had there been a gearbox problem I;m sure they would have said something). MB are disputing this, however they did send the gearbox off to their warranty department in Germany - who said they would not honour a refund.
So i;m back to trying to recover my money from MB brentford. My question is - would the seal blowing on the gearbox, and subsequent oil befing thrown out, be a reason for the gearbox breaking?
Submitted: 3 years ago.
Category: Mercedes
Expert:  Shantal-Mod replied 3 years ago.


I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you,


Customer: replied 3 years ago.

Please continue the search.

Expert:  Shantal-Mod replied 3 years ago.


Thanks for getting back to me. We will continue to look for a Professional to assist you.

Thank you for your patience,


Expert:  Billy replied 3 years ago.
Hello and welcome! I'm Billy and i will assist you with this.

My apologies for the delay, thank you for your patience.

In direct response, yes, the seal blowing, and oil leaking out, so the oil level drops dramatically, the gearbox would get damaged in more than a way.

However, a few remarks on the details you reported:
- the technicians who were checking the suspension and repairing it, they might not notice any gearbox problems. As it is a completely different issue.

Now i will elaborate:
If the gearbox was working fine until the seal got blown, and after you had metal shreds in the sump, and the gearbox was diagnosed in need of replacement, and if when the seal got blown, the fluid level in the gearbox dropped dramatically, the gearbox if used would suffer damage. Eventually it would require replacement.
The fluid (oil) in the transmission has many functions:
- it lubricates (hence the lack of would cause metal to metal friction and overheating, and shreds, and the metal parts would get worn)
- it acts as a coolant for the transmission (so lack of fluid would cause overheating, thus damage)
- it conveys hydraulic pressure to the clutches (so the lack of fluid would cause low pressure, thus clutches slipping and wearing out)
- it conveys power in the torque converter (thus, the lack of would cause slipping in the converter, and the torque converter would also get damaged).

Having refused to cover the gearbox, you should ask MB why? why do they think that this case is irrelevant, and what was the real cause of damage, and when was it already damaged?

I hope this sheds some more lights on your "frustrating" problem.

Thank you for your trust! Get back to me if you need more assistance...Thank you in advance for the positive rating...

Regards, Billy
Customer: replied 3 years ago.



Thanks for the answer. MB are saying that the seal that blew was not 'under pressure' and hence not enough oil would have leaked out to cause damage. My take on that is - nonsense - the seal is there to keep oil in, whether it was under pressure or not. If the seal blew while the car was going along, oil would leak out and enough could leak out to cause damage to the gearbox components. Also when I broke down, the car was really smoking and the amount of oil under the car was not insignificant to my mind.

Expert:  Billy replied 3 years ago.

You need to ask them the following questions, and tell them that since they are so positive, and so scientific about this to be precise:
- how much oil have leaked out? (how do they know)?
- how much oil drop would be enough to damage the transmission?
- is the amount of oil leaking the same with engine on/off, and vehicle moving or not?

And kindly get back to me with their responses, as i cannot wait to hear it....

Best of luck for now!
Customer: replied 3 years ago.



Thanks actually I have asked exactly these questions already in writing and am waiting for an answer - its been 2 months so far.

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