900 L4-1985cc 2.0L DOHC (1986)
Coolant Line/Hose: Customer Interest
Heater - Fluctuating Output
Subject:
Bypass Valve for the Heater System
Application:
1985- 900 Models With 16-Valve Engines
CATEGORY Body
SECTION
PAGE
8
11
ISSUE
CODE
11/90-0072
854
Figure 1
On certain cars with plastic heater valves the flow of heat from the heater core may fluctuate depending on driving conditions. The heater control valve
has a constant bypass which may result in insufficient coolant flow at low engine speeds to provide a comfortable level of heat during certain situations,
such as stop-and-go driving.
An auxiliary bypass valve has been developed to help remedy complaints of fluctuating heater output. The service kit is designed for use on cars wfth
16-valve engines, with or without ABS brakes. The previously-released kit containing the circulation pump (see PSI 03/90-1221) should henceforth only
be installed on cars with 8-valve engines, -M88. To further assist the operation of the bypass valve kit a 89~C thermostat, P/N 88 17 298, may be
installed in place of the standard 82~C thermostat, P/N 88 17 538.
Before installing the bypass kit, investigate and remedy all other potential sources of insufficient heat output such as a blocked heater core, low coolant
level, faulty thermostat, etc.
NOTE
This kit will not remedy complaints of insufficient heat during highway driving or driving conditions other than stop-and-go traffic. There is sufficient
coolant flow through the heater core at any engine speed above approximately 1500 rpm and the bypass valve will not improve a complaint of poor heat
at speeds above thls level.
Heater Bypass Valve Kit, B202 Turbo
41 21 745
^
Bypass Valve 40 73 706
^
Hose, water pump/pipe - bypass valve 41 21 729
^
Hose, lower control valve - bypass valve 41 21 703
^
Hose, upper control valve - bypass valve 41 21 695
^
Hose, coolant pipe - bypass valve 41 21 711
^
Hose clamps (Qty. 4) 79 70 080
^
Tie strap (Qty. 1) 79 71 880
Heater Bypass Valve Kit, B202 Nat. Asp.
41 21 687
^
Bypass Valve 40 73 706
^
Hose, water pump/throttle housing - 41 21 737 bypass valve
^
Hose, lower control valve - bypass valve 41 21 703
^
Hose, upper control valve - bypass valve 41 21 695