Hot Engine
- Warm engine to operating temperature. Raise engine to 3500 RPM and close throttle suddenly several times. Check for vacuum at air valve hose No. 26. If vacuum is present, system is okay.
- If no vacuum is present, disconnect vacuum hoses No. 19 and 20 from control valve and check for vacuum. If vacuum is present at both hoses, replace vacuum control valve and retest. If no vacuum is present at hose No. 19, replace thermovalve D and retest.
- If no vacuum is present at hose No. 20, check vacuum line to intake manifold for leaks or blockage. Repair or clean as necessary and retest.