7/12/16 - Owned for 31 yrs -1985 Cheetah 166 w/Merc.140 MR hp (181cid) & Alpha stern drive with 412 operating hours. Conducted normal maintenance over years. Recently conducted maintenance on upper and lower stern drive with new shift shaft, oil seals, bearings, water pump, u-joints & yoke shaft splines in good condition, installed new gimbal bearing & seal with recommended driver/bar, carefully checked alignment on engine coupling (splines also in good condition) and made small adjustment at front engine mount, engine tuned with new points, condenser and plugs, with dwell and timing on spec.
....Conducted first in water test with engine at spec., normal operating temperature and oil pressure, the engine & stern drive performed flawlessly as in prior years. When engine exceeded 1500 RPM, a loud metallic clicking sound emanated from left rear of the engine behind the starter in area of the lower bellhousing, and would increase 25% in loudness at 2000 RPM. Decreased engine rpm to 1500 or less & the metallic clicking fully disappears. This clicking occurred regardless of the sterndrive's position.
....Removed sterndrive and tested engine (water fed through water intake on housing), same loud metallic clicking sound began at 1500 RPM, increase in loudness at 2000 RPM & fully ceases at 1500 RPM or less.
....This metallic clicking has never occurred before. Insight on this matter would be greatly appreciated.
Thanks, RBell, Virginia
....Conducted first in water test with engine at spec., normal operating temperature and oil pressure, the engine & stern drive performed flawlessly as in prior years. When engine exceeded 1500 RPM, a loud metallic clicking sound emanated from left rear of the engine behind the starter in area of the lower bellhousing, and would increase 25% in loudness at 2000 RPM. Decreased engine rpm to 1500 or less & the metallic clicking fully disappears. This clicking occurred regardless of the sterndrive's position.
....Removed sterndrive and tested engine (water fed through water intake on housing), same loud metallic clicking sound began at 1500 RPM, increase in loudness at 2000 RPM & fully ceases at 1500 RPM or less.
....This metallic clicking has never occurred before. Insight on this matter would be greatly appreciated.
Thanks, RBell, Virginia