Emissions - Coolant Leak at BAC Valve

88mazda06

Category 4
Applicable Model/s 1988 626/MX-6
Subject BYPASS AIR CONTROL VALVE
Bulletin No. 045/88
Issued 3/21/88
Revised 8/9/88



DESCRIPTION

The following conditions may be caused by coolant leakage from the BAC (Bypass Air Control) valve.

^ Idle speed hunting at approximately 1700 rpm
^ White exhaust smoke
^ Engine coolant loss
^ Engine overheating

If you encounter these problems, please carry out the checking procedure listed in this bulletin.



INSPECTION PROCEDURE

1. Coolant Circulation Check at BAC Valve

Check the engine oil and coolant level and their condition.

Start the engine and warm it up to the normal operating temperature.

Check if the engine runs normally and the ISC valve is hot by lightly touching the ISC valve.

If the engine runs normally and the ISC valve is hot, then follow the next procedure.



2. Coolant Leakage Test

Connect a cooling system pressure tester and pressurize the system to 15 psi. (1.05 kg.sq.cm. 103 kpa)

Make sure that the pressure holds for 5 minutes.

WARNING:
When removing either the radiator cap or the tester, loosen it slowly until the pressure in the radiator is released, and then remove it.



If the pressure holds more than 5 minutes, the trouble is not caused by the coolant leakage from the BAC valve. See the 626/MX-6 Workshop Manual for further troubleshooting.

If the pressure decreases within 5 minutes, check the leakage area.

^ At the BAC area. Go to step 3.
^ If it is other than the BAC valve, perform the necessary repair.




3. Remove the BAC valve from the throttle body. Check if coolant is found in the air passage of BAC valve or on the throttle body.

If so, replace the BAC valve with a new one.




4. Use a new gasket and apply sealant to both sides of the gasket.

5. Check the engine oil and coolant level and their condition. If necessary, add or replace them.

PARTS INFORMATION


PART NUMBER DESCRIPTION APPLIED MODEL

F201 20 660 Bypass Air Control Valve 626/MX-6 M/T *

F202 20 660 Bypass Air Control Valve 626/MX-6 A/T *

F248 13 W89 Gasket 626/MX-6 A/T & M/T


WARRANTY INFORMATION

Customer Comment Code: 1N
Damage Code: 02
* Part No. of Main Cause: F201 20 660 (for M/T model), BAC valve F202 20 660 (for A/T model), BAC valve
Operation No: 20660A-R-X (BAC valve R&R)
Labor Hour: 0.4 Hr.


The revised sections are indicated by an asterisk. Please replace the original bulletin with this revised bulletin.