NEW HEATER VALVE TO FIX DELAYED HEAT OUTPUT PROBLEM
TECHNICAL SERVICE BULLETIN
Reference Number(s): 64 05 93 (3750)
DELAYED HEATER OUTPUT

Model(s): 1991-93 BMW (E31) 850 Series

1988-93 BMW (E32) 735/750 Series

1989-93 BMW (E34) 525/535/M5 Series

1991-93 BMW (E36) 318/325/M3 Series

Group: 64 - Heating and Air Conditioning

Bulletin No.: 64 05 93 (3750)

Date: April, 1993
SITUATION

We have received a few E32/E34 vehicle complaints of reduced temperature heater output, during the first 10-15 minutes of vehicle operation after a cold start in low ambient temperatures.
CAUSE

The water valve can stick due to changes to the internal coating. This occurs primarily with the E32/M60, but is also possible with other vehicles.
CORRECTION

Verify that there are no faults in the IHKA (or IHKR) control module. If no faults are found, and a check of the coolant system reveals no leaks or obvious defects, replace the water valves with new modified parts.
PARTS INFORMATION

Improved water valves have a white paint dot next to theDate: code. Water valve part numbers have not changed. The BMW Parts supply has been purged of the older water valves.

PARTS INFORMATION TABLE
Part Description Part Number
E31/E32/E34 Water Valve (modified) 64 11 1 391 958
E36 Water Valve (modified) 64 11 1 387 319