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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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I bought a Sept 2004 clk55amg 78k miles FMBSH from an indy

Customer Question

I bought a Sept 2004 clk55amg 78k miles FMBSH from an indy dealer and 2 days later the transmission failed. It seems to be that common fault of cross contamination of glycol. The supplying garage have taken the car back and are due to propose a repair plan to be done by MB in Sheffield, but not replacement of the box! How can I be sure that say a new rad, full flush of everything etc has really done the job and it will not fail on me down the track?
Submitted: 2 years ago.
Category: Mercedes
Expert:  Shantal-Mod replied 2 years ago.
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Expert:  Stan replied 2 years ago.
The repair scope depends on the concentration of glycol (coolant) in the transmission fluid. In case of light contamination, undertaken repairs are prescribed by the manufacturer.
In case of heaviest level of glycol concentration, then the transmission must be replaced.
You can ask the repairer for the glycol test paper and see what color it is and compare it to the manufacturer's repair instructions. They all have to be stored with the workshop order at the dealer.

best regards,
Customer: replied 2 years ago.
Hi Stan can you tell me what level (so what constitutes heavy?) of glycol contamination indicates replacement rather than repair? Is that measured by a colour interpretation of the paper or is it more scientific than that? Best Andy
Expert:  Stan replied 2 years ago.
Sorry, the glycol test does not prescribe the transmission replacement.
The following must be done depending on the result per manufacturer specs:

''- As of a glycol content greater than 100 mg/l. Exchange radiator, flush torque converter, lines and transmission.

If the complaint is still reproducible after the flushing routine, only the torque converter should additionally be replaced. ''

Result of the test is shown as a color of the test paper. Test itself is quite specific.
If the transmission does not exhibit any symptoms after the flush, transmission is considered to be in order by manufacturer's specifications.
Of course, if transmission gears are slipping after the flush, then the coolant has damaged clutch plates, torque converter replacement will not help.