Pressure Cap - Procedure & Tool for Testing Revised Cap
87saab02FILE IN S.I. Man VOL. I
SEC. A-2 PG. 200
Service Information
SUBJECT: PROCEDURE FOR CHECKING NEW TYPE ISSUE: 02/87-934 EXPANSION TANK PRESSURE CAP
APPLICATION: PRESSURE CAP WITH BOTH PRESSURE AND VACUUM VALVES
A procedure and special adapter are now available for checking the opening pressures of the new style pressure cap. This cap was introduced during model year 1987 from the following VIN Serial Nos.:
H1000423- H2000404- H3000908- H7001510-
The new cap has separate internal valves controlling both vacuum and pressure. The procedure below allows the pressure valve of the new cap to be checked using the adapter. There are no means set up for checking the vacuum valve as this has proven unnecessary.
Pressure Cap Adapter 83-94-140
The adapter is available from your servicing Saab Parts Depot. Do not attempt to check old style cap (83-35- 069, single valve type) using this procedure. Results are not consistent due to the single valve design.
Opening Pressures:
Valve A 13.1 - 17.4 psi
(0.9 - 1.2 bar)
Valve B 1.02 psi max.
(0.07 bar max.)
Checking Procedure:
1. Remove the pressure cap from the tank while the coolant is still warm.
Warning! Boiling coolant can cause serious burns. Always open the cap on the expansion tank slowly and allow any steam to escape before you remove the cap.
2. Fit the pressure cap to the adapter 83-94-140 and the adapter to a reliable cooling system tester.
3. Submerge the cap into a pan of room temperature coolant mix (50/50).
Slowly raise the pressure until air bubbles can be seen coming from the cap. Note the pressure at which the bubbles appear.
Now, without altering the pressure, wait until no more bubbles are visible and read off the pressure from the gauge. The opening and closing pressure must fall within 13.1 - 17.4 psi (0.9-1.2 bar).
A cap that does not meet the above specifications should be replaced.