Sudden tapping from engine.

[38mess]

Perkins M30, running fine all morning then pulling away from the pontoon a sudden tapping noise some blue smoke and loss of a cylinder I think. Stopped engine had a quick look. Started engine again and all fine, running ok. I'm guessing a stuck injector, but open to other suggestions.

 

[lynnx22]

Perkins 4107, sounded like a blown big end.
Pulled engine, rebuilt it (as it was out) but it was, in fact, a stuck injector duh!

 

[scottie]

Do injectors suddenly stick ?
Valves do
Not relevant in ohv side side valves were notorious for it but were a simple fix

 

[lynnx22]

I think "stuck" can mean "broken" lol

 

[david_bagshaw]

I would suggest a bit of carbon flaked off and held a valve open for a short while...

 

[oldgit]

AQD40A around 3500 + hours

Half way to somewhere on tickover and a sudden and noticeable tapping noise.
Slowed right down and headed for a nearbye commercial tug mooring.
Had to increase revs considerably nearly full throttle to stem tide, tapping stopped.
Was told later that the valve seats on 40 series had tendency to come loose and opening throttle may have knocked the seat back in.
It never reoccurred.