I have 7.4l 454 mercruisers. I recently noticed a dron in RPM on the PORT engine while running as cruising speed (2000-3000 rpm range).
The PORT engine would drop 200-500 RPM and recover back after 5-20 seconds on average.
Pulled all the plugs and verified no water leaking.
Performed compression checks on all cylinders 130-140 psi on all cylinders execpt one at 125 psi.
Rechecked the 125 psi cylinder and received a fluctuating psi indication that did not repeat 125 psi. Check next cylinder in line
and also received a fluctuating psi indication an that cylinder also. I am not sure if the compression test gause is malfunctioning or not.
The ticking sound was audible with the PORT engine at the exhasut and near the valve cover.
Have not tried pullingthe plug wire on that cylinder yet.
Any suggestions/info would be helpfull.
HB2TA
The PORT engine would drop 200-500 RPM and recover back after 5-20 seconds on average.
Pulled all the plugs and verified no water leaking.
Performed compression checks on all cylinders 130-140 psi on all cylinders execpt one at 125 psi.
Rechecked the 125 psi cylinder and received a fluctuating psi indication that did not repeat 125 psi. Check next cylinder in line
and also received a fluctuating psi indication an that cylinder also. I am not sure if the compression test gause is malfunctioning or not.
The ticking sound was audible with the PORT engine at the exhasut and near the valve cover.
Have not tried pullingthe plug wire on that cylinder yet.
Any suggestions/info would be helpfull.
HB2TA
