2001 OX66 200 Pinging/Knocking Noise

[nickzlb77]

Hey All, usually an IO guy so I apologize in advance. 2001 OX66 200 saltwater series II FI.

To me it sounds like a standard pinging noise coming from cylinder 1.

Apparently the motor had an oiling issue prior that was resolved. Good compression on all cylinders. I did find he had hot plugs in it (BR7HS vs BR8 or 9).

When the plug wire is pulled from cylinder 1 noise goes away. Comes back as soon as plug wire is reconnected. Was thinking an oiling issue to that 1 cylinder or a bad injector? Someone had mentioned a top main bearing as well. Any insight?

Vid for reference
https://youtu.be/vf41RgbodjM

[TownsendsFJR1300]

That's Not a detonation knock or "pinging".

I'd be curious to see pic's of the hotter plugs...

I suspect a bad wrist pin or lower connecting rod bearing. That noise is consistent with a bad bearing-
Pulling the spark from the cylinder of course kills the power(of course) from it, thus no combustion to PUSH DOWN hard on the piston (causing the knock)


The "oiling issue", can you elaborate? Too much oil (thus the hotter plugs to try and prevent fouling) or the oil injection stopped/leak, etc?

.

[nickzlb77]

Hey Scott thank for the reply.

Owner said the pump wouldn’t fill the primary tank on the engine automatically which led him to fill the engine tank manually often. But he bought the boat in that state so who knows when it started and how the previous owner handled it (or when he figured it out) Found an issue in the harness from the level sensor to the ECM and repaired now pump works as it should.

The BR7s were wiped out hard to believe it fired at all. Ton of buildup (sludgy). You could think there would be less given the heat range but again unsure of the full history, maintenance habits of prior owner, etc.

It is significantly down on power over 3300 rpm. As mentioned good compression across board. my first thought was a bearing or wrist pin but I’d have expected it to get significantly worse with RPM which it doesn’t.

So far changed fuel filter, separator and oil filter in tank.

It does sound like it has to come apart.

[99yam40]

does this motor have the o2 sensor hooked to #1 cylinder?
I have heard they can make some type of noise when the dog bone gets loose in the hole it sits in. but I have no idea what it sounds like

[mjm-1957]

Starboard top cylinder has the O2 dog bone.

[zenoahphobic]

Sounds to me like that cylinder that the plug is misfiring.
Maybe stupid question : how does it run with a new correct heat range plug?