Volvo Penta 5.7 GSI Knock

[2nafsh]

In the late summer the engine developed a knock. It only knocks when it is under a load and above 2100 rpm. By the sounds of it, it doesn't seem to be in the top end so I'm thinking it is a rod knock. Wouldn't a rod knock present itself at any rpm and whether it was under a load or not? It has become worse every time I take the boat out. I'm about ready to take it out and tear it down but would like some confirmation as to what may be wrong. Any help would be appreciated.

 

[Bondo]

Re: Volvo Penta 5.7 GSI Knock

It has become worse every time I take the boat out. I'm about ready to take it out and tear it down but

Ayuh,..... Welcome Aboard,....

It sounds to Me, there Ain't any Buts,....

Open it Up,+ Look........

 

[chiefalen]

Re: Volvo Penta 5.7 GSI Knock

What else was it doing besides knocking ?

Yea yank it out and tear it apart, let us what it looks like.

Maybe it's not to serious.

Welcome aboard, wish it wasn't under these circumstances.

 

[KJSmitty]

Re: Volvo Penta 5.7 GSI Knock

Out of curiosity,

- What year of boat/engine, hrs on engine, and typical oil pressure at idle and above 2500??

- Who maintains the engine/boat - when was the last oil change and weight of oil?

Inquiring minds want to know....

- You could always try pulling one spark-plug wire at a time to isolate the rod/piston etc.. Somewhat unorthodox yet it worked for me once in ID'ing the problem cylinder/rod.


And yes, welcome - and sorry to hear about your issue.
-- New engine for Christmas??

Best of luck

 

[chiefalen]

Re: Volvo Penta 5.7 GSI Knock

Why run it any more than it has to. Me soon as i heard the knocking i wouldn't be taking it out on the water till i tore it down.

To wait and hear the noise get worse and worse don't make sense to me.

Not chiding, just me.

Now when you do see if a connecting rod went maybe you can get away with a new one, if it's that.

But to keep running it in my mind don't make sense. My thoughts also connecting rod, wrist pin, something on the bottom end.

But what i know, i'm a ole washed up geezer.

 

[JustJason]

Re: Volvo Penta 5.7 GSI Knock

Buy this....

http://www.sears.com/shc/s/p_10153_12605_00945164000P


And you should be able to get a pretty good idea of where your problem is.

 

[2nafsh]

Re: Volvo Penta 5.7 GSI Knock

Hey Everybody,

Thanks for all of the replies.

First off let me clarify something, I wasn't taking the boat out for joyrides once it started knocking. I would find somebody with more experience than I have to ride along with me and get their opinion. The only way to make it knock is under a load (boat moving through the water) above 2100 rpm. So, running the boat was for diagnostic purposes. It has been sitting up all fall except for these occasional trouble shooting trips.

Now to answer some questions:

The age of the motor is somewhat ambiguous in that two years ago I took a chance on a running takeout and put it in my boat. According to the computer it only had 200 hours on it. I got 2 summers out of it, maybe that is more than I should expect.

The oil pressure is always good at >40psi and I maintain the engine. I always change the oil at the recommended interval of 100 hrs and use SAE 30 that meets or exceeds the specified detergent level.

I like the idea of a new engine for Christmas! I'm just not sure the wife will go along with it.

Thanks again for all the suggestions and I wish everybody a Merry Christmas and a Happy New Year.