2003 Volvo Penta 5.7 - Surge of High RPMs

[GJOges]

Had my Regal 2200 boat out over the weekend and after a swim break, we started driving at 5,000 RPM at less than 10 MPH. The RPMs would increase/decrease relative to how much throttle I was applying and kept this up for 15 minutes. I stopped a few times during this event, shut-off the engine, checked the propeller, engine temp was OK (170-175 F), check engine synthetic oil (no water/burnt smell), no excess water in bilge, to make sure we were OK. This boat & propeller should top out at 45 MPH at this RPM. Less than 100 hrs on this engine and really gets used only 5 times per summer but I try to keep it in good shape stored indoors. After the 15 minutes of drivng at 10 MPH, the RPMs went down to normal levels and I was able to return to full throttle at 5,000 RPMs. Loaded it 10 minutes later on our trailer and am wondering what will happen next time I take it out.

The engine did not seem overly stressed at 5,000 RPMs and 10 MPH, so could it just be my RPM gauge or hardware? Could my outdrive unit be screwed up or on the brink, and this was just a hint of what's to come? I haven't checked my outdrive oil for problems/level just yet and will tonight, but changed the outdrive oil a couple of outings ago without any issues.

Any helpful hints??

Thanks!

 

[Maclin]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

Could the prop have been fouled with weeds and then cleared? Weeds can put the prop into a no-thrust condition, easiest thing there is to reverse at low rpm's.

At first i was thinking a spun prop hub, but they usually do not "come back" and catch again, and certainly not at 100%.

 

[GJOges]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

I wasn't in a real "weedy" area, and once during the ordeal I did check the prop for anything hanging it up and movement, but the high RPMs at 10 MPH just continued. Thanks

 

[Don S]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

You may have a slipping cone clutch in the drive, or more likely the shift cable isn't always putting the drive all they way into gear.

Check your gear lube and see if there is water in it or the oil is burned.

 

[GJOges]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

Thanks Oracle, I'll see what I find!

 

[GJOges]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

Fluid level in outdrive checked OK and no apparent water. Now the big question.... when I changed the outdrive oil a few weeks back I used Mobil "LS" 75W-90 when I should have used Mobilube 1 "SHC". Both meet the GL-5 specs but the "LS" is limited slip with a sulphur additive. Big mistake and did I ruin my outdrive grears after about 3 hrs of medium run time? My plan now is replace the "LS" with "SHC" and see if I get the same high RPM issue. Any advice?

 

[Don S]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

Big mistake and did I ruin my outdrive grears after about 3 hrs of medium run time?

Have no idea, never tried it to find out. Change it out and see what happens. I would think the most you would need is a new shift cone if it doesn't clear up.

 

[GJOges]

Re: 2003 Volvo Penta 5.7 - Surge of High RPMs

Drained outdrive oil and unfortunately have water in my oil. I am assuming that the water is causing the shifting problems so I will take it in to have them pull the outdrive and start replacing seals.