Turbocharger - Troubleshooting Hints
83mercedes01TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: December, 1983 REF.NO. MBNA 09/3
SUBJECT: UNNECESSARY WARRANTY REPLACEMENT OF TURBOCHARGERS MODELS 123.133/153/193 AND 126.120
The high number of unnecessary turbocharger replacements is the reason for once again drawing your attention to the established test and checkout procedures in the MBNA Service Literature and Microfiche System.
Service Information MBNA 09/2 of August, 1981, and 09/8 of February, 1983 describe in detail the procedures for performance evaluation and troubleshooting of the turbocharger, including the often overlooked "overload protection system".
In addition, job number 09-425 in the Microfiche System explains the boost pressure test. Test numbers 07-0000 25 and 07-0000 26 in the Diagnostic Manual repeat the test and checkout procedures for the overload protection system and boost pressure.
Please refer your personnel to these instructions to avoid unnecessary replacements in the future and pay "Special Attention" to the following points:
1. Hot crankcase blow-by gases contain a small amount of oil vapors which will condense on the relatively cool air intake scoop and turbocharger compressor housing walls, creating the impression that lube oil is coming out of the turbo center housing. Even some oil accumulation in the wastegate hose and a slight drip out of the wastegate vent hole itself, is caused by this process and is not a result of leaking turbo seals. The seals of the turbo rotating unit, constructed in the form of oil slingers (dynamic seals) and ring seals are almost never the reason for oil leaks.
2. The turbo and engine test data must be listed on the warranty claim (boost pressure, acceleration, stall speed, etc.) in case of turbo replacement. The measured boost pressure of any replaced turbo must be documented quantitatively (measured values; not qualitatively, such as "low boost", "high boost", etc.) in order to make it possible for MBNA to retest and compare the returned material. Also describe in detail any other malfunction, such as "Turbo noisy", by providing the speed range and any other pertinent information. Failure to comply with these instructions may result in the denial of the warranty claim.
3. Turbocharger replacement for high engine oil consumption or oil leaks, without prior Zone approval, is not acceptable under warranty.
Please advise all your responsible personnel of the new regulation which will take effect immediately.