Warm Engine
- Warm engine to operating temperature. Raise engine to 3500 RPM and close throttle suddenly several times. Check for vacuum at air valve hose number 26.
- If vacuum is present, system is okay. If no vacuum is present, disconnect vacuum hoses number 19 and 20 from control valve and check for vacuum.
- If vacuum is present at both hoses removed in step 2), replace vacuum control valve and retest. If no vacuum is present at hose number 19, replace thermovalve D and retest.
- If no vacuum is present at hose number 20, check vacuum line to intake manifold for leaks or blockage. Repair or clean as necessary and retest.