Volvo Penta AQ125B WOT issues

[xsnoboard]

Hello,

I am having an ongoing issue with my Volvo Penta AQ125B with WOT issues and planing issues (most likely related).

If I have 3 people total on board I have issues planing out. Sits at about 3000 RPMS until someone goes to the front of the boat and it finally planes out after 15 seconds or so. Also, WOT is about 4000 RPMS @ like 30mph(Tach might not be accurate) If I'm WOT and take a decent turn you can feel the lack of power and it will slow down a bit.

When I set the timing to be in spec the boat runs horrible, can only hit like 2200 RPM WOT. I have to advance the timing all the way for it to run almost right...

Thanks,

Cory

 

[2stroke1971]

Re: Volvo Penta AQ125B WOT issues

What kind of boat? I have a Bayliner Capri, 20 foot cuddy with an AQ125--mine is an A but in any case, mine is alot of boat for that little motor. Mine was a slug with anymore than 2 people.....I rebuilt the motor and it improved a good bit but before the rebuild, the difference between just me on board and then the whole family was dramatic.
What will yours do with only you on it?

 

[Mullin]

Re: Volvo Penta AQ125B WOT issues

Does it have this problem only on the water, or running on muffs too?

Did you check the pulley alignment marks and make sure the belt didn't jump a tooth (or more)? It's pretty common on this motor.

Have you adjusted the trim? The locking bar on the outdrive has three different spots for adjusting the trim. The cuddy models benefit a lot from trim tabs from what I hear.

4000rpms is low, 30mph is pretty good. My bowrider can hit a max of 32mph with just me on it, and about 28mph when loaded up with people and gear. I'm at High altitude with a 14D x 15P prop, although at sea level I tried a 17p and the original 19p props. At sea level I can get going a little faster, but I think only 35-37 IIRC. And the 19p prop wasn't revving high enough so I use the 17p down the hill.

I like to rev the motor a little high. I have accidentally hit 5600rpm when running by myself up here with the 15p prop, I try to keep it around 5k and it usually stays around there when all loaded up.

 

[xsnoboard]

Re: Volvo Penta AQ125B WOT issues

I have a 1988 17ft Sunbird bowrider. I am running a 14.5inch 19pitch prop. When I ride alone it still cant hit the speeds I should be able too... Although it does plane faster, but I never had this issue when I first had the boat. Boat originally had a 14inch 19 pitch prop but it still planed fine and hit tops speeds fine with the bigger prop.

I adjusted the trim, the boat was pulling to the left a lot, but that did not make a difference. It still pulls a bit but not much.

Maybe the timing belt jumped a tooth. I will look into that.