Signs / Symptoms of Low Compression?

[Yachtsman1304]

I have a 2000 Volvo Penta 5.0 Gi PEFS that I am looking for a bit of guidance on. When I splashed it this spring, I was able to get 4900 RPM WOT. Now, I can only muster about 4500 - 4600 RPM. The boat is wet slipped so the bottom is totally covered with "growth". I am in a freshwater lake, but even so, there is growth.

Can this 400 or so WOT RPM loss be attributed to the increased drag of the growth and the other hundred pounds plus of gear that is now on the boat since it is in the water all the time?

It starts fine, it idles fine, no back firing, no strange noises, no smoke at all. It does seem to be a little more sluggish to get on plane, but it's a pretty good size boat for the engine anyway. Temperature is right about 160 degrees all the time and oil pressure is good.

I have replaced the plugs and wires and nothing looked out of the ordinary. Cap and rotor are next, just because it's time.

I read the sticky at the beginning of the forum and went through the checklist in my mind and when I got to compression, I swallowed hard...this is going to be expensive. I will be doing a compression test at the end of the season (which for us in Michigan is rapidly approaching), but I just want to get some of your thoughts.

Thanks in advance for any responses.

 

[alldodge]

Can this 400 or so WOT RPM loss be attributed to the increased drag of the growth and the other hundred pounds plus of gear that is now on the boat since it is in the water all the time?

Yes, it can drop you that far, all depends on how much. Don't think you have a compression issue but it is always good to check the health of the motor.

 

[Bondo]

Can this 400 or so WOT RPM loss be attributed to the increased drag of the growth and the other hundred pounds plus of gear that is now on the boat since it is in the water all the time?

Ayuh,.... Absolutely,.... No doubt,.... It'll get worse with time,.... Sealife on the hull is like tryin' to drag an anchor 'round,.....