300SD (126.120) L5-3.0L DSL Turbo (617.951) (1982)
Technical Service Bulletin # 27_006
Date: 830701
A/T - Vacuum Control Valve Updated
TO:
OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE:
July 1983 REF. NO. MBNA 27/6
SUBJECT:
VACUUM CONTROL VALVE ADJUSTMENT TO IMPROVE AUTOMATIC TRANSMISSION SHIFT QUALITY, VEHICLES
WITH DIESEL ENGINES CHASSIS 123 AND 126
Vacuum Control Valve
NOTE:
This Service Information supersedes MBNA 27/1, Jan. 1981, (modification of valve body M.Y. 1980, see attached work instruction) MBNA
27/3, Nov. 1981, and "Testing of Vacuum Control Valve" (Group 27, page 33 of 1983 Introduction Manual).
Since the beginning of Model Year 1981, a modified vacuum control valve was installed in production. Poor shift quality at partial throttle can be
improved by adjusting this modified vacuum control valve.
If test value is found to be out of specified tolerance, start test by adjusting valve to an initial value of 145 mbar (Engines 617.91, 617.95), 200 mbar
(Engine 616.91).
If the complaint is hard up-shifts, but the valve is found to be within specifications, the valve should be adjusted to the upper tolerance limit; in case of
slipping during upshifts, adjust valve to lower limit.
Test Values (Millibar)
Vacuum
Control
EGR
Engine
Valve
Valve
616.91
155-215
200-240
617.95
110-160
150-190
617.91
110-160
390-460
617.95*
320-350
*California version, 1980 model year.
FIGURE 1 - PUSH ROD CONFIGURATIONS
Procedure
IMPORTANT:
Push rod for vacuum valve should be checked for proper basic length and adjusted as required. Refer to Figure 1. At full throttle, a
clearance of 0.5 mm (0.020 in.) should be maintained between the actuating lever and full throttle stop.