Thread: Engine Knocking
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noah
 
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Default Engine Knocking

On Thu, 4 Sep 2003 20:47:12 -0400, "Frank Taylor, Jr."
wrote:

I'm almost afraid to ask this question for fear of what answers I might get
but here goes:

My boat has a Volvo Penta 5.7 GS engine (carbureted) with 240 hours on it.
It is very well taken care of. Today as I cranked it up, I let go of the
key before the engine caught on and from the sound of things, I knew what
had happened. The engine actually kicked backwards one stroke and sucked up
some water.

I figured, "no problem, this has happened before and I can handle this." I
took out all of the plugs and cranked the engine to let the water blow out
of the cylinders, dried the plugs and put them back in and proceeded to
start the engine.

The engine started but there was a pretty loud knocking sound. I shut it
down to check my plug connections and to check to make sure I had not mixed
up and plugged the wires back in the wrong order and everything was okay. I
started it once again and still had that darned noise.

Any ideas?

I'm really nervous about this one.

Frank


Frank, even a small amount of water remaining in the cylinder will
raise hell with your engine. It changes the compression ratio,
drastically, and can cause ring and valve problems. In a "horizontal"
engine, it won't just "blow out" the exhaust.

Hopefully, there is no damage to the piston, rod, or crank. Pull
those plugs again, and check each cylinder for water (with a
flashlight and magnifying glass, if you have to). If you have water
in it, wick it out with cotton rags cut into strips, or cotton rope
(cheap clothesline rope).

If it knocks after this, you have a bigger problem. The hydraulic
lock may have damaged bearings or the crank. (

Good luck.
noah