Sorry but if I pulled a plug out of a motor that had peppering first thing I would do is pull out the compression tester. Wouldn't you?

That ticking you heard beforehand could be a diverter in the Corsa exhaust.

i see no signs of a lean cylinder so a broken forged piston is not likely,a borescope through the plug hole would be what i would do if i thought it had detonated a piston.mpi engines can and do have injector issues from time to time and if nothing gets done to correct the bad injector bad things can happen.the op said it was still running fine just making noise so i would rule out other problems before i pulled the engine out.edit in,i see no peppering,only carbon build up but without close inspection with a magnifying glass i would not see it anyway.

i have seen them knock from a bad sparkplug wire..called spark knock...should have pulled plug wire one by one until the knock went away,,if it did not then its not a rod bearing..

bb,not being a smart azz but this is not a nitrous deal,jmo.

Top 4 plugs are from the Odd side bank( slightley different debris on thme) . Top left and right plugs are from Cyl # 5 & 7

Yep heads were redone 2 years ago 87 hrs accordign to hour meter. Valves checked out fine and were re cut and reused.

Did that test this spring on first start up with broom stick up the pipe :). sounds funny but keeps metal flapper from flapping around, HAHA!

Ill have a bore scope tomorrow. Co worker has one.

Im searching youtube now for the same noise I have. I dont think im the first person to ever have this noise :) HAHA.

Yeah I got ya. It's just in the last 2-3 years I've seen more detonated boat motors than in the last 10. There is definately peppering on that plug. Is it from running lean? Hard to tell after the motor has been idled. Wasn't really my thinking. If I'd pinched a ring which usually happens with a forged piston and minor detonation a borescope isn't going to tell you much. There is definate signs of detonation on the plug it's hard to tell from the other plugs cause when you supersize it gets very blury.

To the OP the black speckling on the porcelain is oil the got past the rings from detonation. If you get a high powered magnifying glass and examine the porcelain carefull I bet you will see more black spots and some aluminum shiny spots. Black is oil shiny is aluminum from the piston.

Deffentley NOT like this . This I would call a thud.
https://www.youtube.com/watch?v=1aHz4yZoNzA

This is close just louder.

https://www.youtube.com/watch?v=Pu2RHsIGBXU

https://www.youtube.com/watch?v=Pk1zX_0mKjg



Also Engine ran fine, no miss, no rough idle, nothing.

He has an MPI / ECM controlled engine not the best choice just start yanking plugs wires while engine is running You can do a cylinder drop test with proper scan tool.

I could not see pepper specks on the white insulators of the spark plugs in that one pic. If you do, that is a sign of detonation.

possible Rod bolt ????

Plugs out spin motor by hand - does it feel normal and sound ???


comp test and leak down test or start pulling the heads since the exhaust manifolds are off.

From ManofWar's thread.

This is what my ticking sounds was before it turned into a knock knock joke.

https://www.youtube.com/watch?v=P2FnlFBM5_A