Engine Knocking noise
 

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

Engine Knocking noise
 

Remove all the plugs. Use a straightened coat hanger wire or straight
piece of welding rod as a measuring stick and put it in one plug hole.
Feel the piston as close as you can get to the hole. Turn the engine
by hand (no compression with plugs out) until the measuring rod is at
its highest point...top dead center. Mark the rod at a reference
point so you can repeat this measurement. While feeling with the rod
in your hand, move the crank back and forth and feel that the piston
moves up and down precisely with no "slop" caused by broken bearing
sleeves or rods...the mechanical parts in the crankcase.

Measure TDC and the slop in all the holes. Pray you don't find one
that's "loose" or measures TDC LOWER than the others. All pistons
should come up in the holes to the top exactly the same. If you bent
a rod, you'll find it, easy enough.......and you can "feel" what's
"loose" and knocking.....

Best of luck. Don't run it this way....


On Thu, 4 Sep 2003 20:47:38 -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



Larry

Extremely intelligent life must exist in the universe.
You can tell because they never tried to contact us.