posted 08-04-2001 12:21 AM ET (US)
Greetings:Three weeks ago I changed the spark plugs in my 1996 90 HP Johnson. Since then I have noticed a subtle one-per-rev on engine decels. Almost like valves knocking on an overhad cam car engine.
My initial assesment is a loose, or several loose spark plugs - insufficient torque causing a air leak. The noise caused by high engine vacuum at decels. This will be checked shortly.
Other concerns are the VRO system is going south and I am hearing a mechanical bearing noise.
I have had no other problems with the motor and have put ~20 hours on it since changing the plugs. Starting, idle, power, and speed all seem to be normal.
Does anyone have any insight.
'67 Montauk