5.0L Volvo Penta - Knocking Noise?

Question

I have a 1996 Four Winns with 5.0L volva penta. I started hearing a knocking noise. Found #2 cylinder is a little lower. Does anyone have any expierence with this? Any recommendations on where to start to look?

Answer 1

Take it to a repair shop.  Don't run it, knocks usually are caused by a bearing failure, you can do more damage and make the repair more expensive.

Answer 2

Check the compression! If it's low, you've either got a bad head gasket, bad rings, valves are out of adjustment or you've slipped a bearing.

The head gasket can be replaced, the valves are easy to adjust, but if your rings are gone or you've slipped a bearing, your motor is toast. Take it to a mechanic and have them look at it. It may cost you big bucks, but more than likely they can tell you exactly what's wrong with it.

If you did throw a bearing, watch the crank shaft as it's turning. If you see a slight or even major wobble, shut 'er down ASAP!!! That's the best way to tell about the bearings.

Another thing is it might be your fuel. Too low of a grade of fuel will make it knock like crazy. Try emptying your tank and put fresh gas in. You might also want to change out all of your fuel filters at the same time.

Answer 3

First thing is determine where the knocking is coming from. then go from there. If the compression in number 2 is only down about 15 psi thats not really a cause for alarm but if its more than that I would be a little concerned.