Coolant Thermostat - Design Update

Group 11
Engine

Bulletin Number
11 02 99

Woodcliff Lake, NJ
May 1999
Product Engineering

SUBJECT:
Coolant Thermostat

MODEL:
E36 (Including Z3 2.8) with M52 and S52 engines and E39 with M52 engine.

Situation:
Coolant thermostat BMW part number 11 53 1 733 803 was phased into production on 528i models in 7/97.

This thermostat has a single plate design compared to the double plate type part number 11 53 1 712 043 used on early E39 with M52 engines and current E36 models with M52 and S52 engines. (See illustrations below.)

Whenever repairs become necessary on the above models, which require a thermostat replacement, the single plate thermostat part number 11 53 1 733 803 must be used.

If the thermostat is replaced due to an engine over heat condition the thermostat housing should also be replaced on these models.

Note:
Since the E36 models do not incorporate an additional water pump in the heating system as on the E39 models, a reduction in the heating systems temperature output may be noticed with the engine at idle when switching from the double plate to the single plate thermostat.

Double Plate Thermostat - P/N 11 53 1 712 043:

Single Plate Thermostat - P/N 11 53 1 733 803:

Parts Information:
The Electronic Parts Catalog (EPC) lists thermostat part number 11 53 1 712 043 as the replacement part for the E36 models with M52 and S52 engines which should no longer be used during repairs on these models.

Only thermostat, part number 11 53 1 733 803, should be used during repairs on these E36 models.

Note:
Thermostat, part number 11 53 1 712 043, is still a valid part number for other models such as E36 with M42 and M50 engines and E34 with M50 engines and should be used on these models when repairs become necessary as specified in EPC.

Warranty Information:
Information only.