2008 Cruisers 330 with Volvo Penta 8.1Gi engines. V Drive doesnt produce power

[ni7irs]

I noticed this recently that my starboard engine does not produce as much power as the port. It also runs rough at about 2,500 rpm, like its missing, then smooths out when full throttle is applied but is almost 1,500 rpm less than port. I just changed the fuel water separator. The spark arrestors seems clean.

If it was prop, i would think vibration would be at all speeds. If it was a loose lead, i would have engine roughness at all rpm's. Right? Any other thoughts?

 

[Bondo]

I just changed the fuel water separator

Ayuh,.... Did ya examine the contents for water or crud,..??

Is this a dock boat,..??
Any sealife on the hull,..??

 

[alldodge]

Could be many things, low fuel pressure, low compression, one cylinder not firing, ECU picking up a knock and retarding timing. Need some numbers from fuel pressure, compression test, have the motor scanned for codes?

 

[Scott Danforth]

pull the fuel module and look for crud (paint flecs) plugging the screens

 

[ni7irs]

So this is an old post, but now the engine has a louder knocking sound at idle. I do not hear it when it is under load or above idle. I just replaced the fuel pump on it after the fuel pump went bad. There have been numerous tanks of gas through the engine from different sources and it now has a new fuel filter. Oil pressure is very good and I change oil and filter regularly, but never exceed 50 hours. Engine has 275 hours on it now. I installed the Volvo kit that transmit fault codes to my iPad, but forgot to download the data last time I was there. Sound seems to be coming from back of engine down low. Thoughts?

 

[alldodge]

How about a compression test

 

[muc]

an engine miss can cause a knocking noise in V-drives.

 

[ni7irs]

Hi thanks for the replies. So I used a mechanics stethoscope and narrowed the noise to the transmission adjacent to the engine. It’s a bit of a rattle. My old mechanic who is in another city thought it sounded like a flex plate failing. Noise disappears at anything above idle. If it’s shifting ok how soon do I have to deal with this? The noise has been there awhile it just got louder lately.

 

[Bondo]

If it’s shifting ok how soon do I have to deal with this? The noise has been there awhile it just got louder lately.

Ayuh,...... No way to know that,..... could be minutes or days, or weeks,.....

It'll work,........... til it don't,.......

 

[alldodge]

As muc mentioned, V drive transmissions will knock, rattle and such if the motor is idling rough. The rougher the idle gets the motr rattle you get when the transmission is in neutral. The rattle is normal and lets you know if there is an issue, not like a stern drive