ad31 help

[gery w]

Hi all im looking for a bit of advice. The last couple of times ive had the boat out first time oppening the taps it struggles to build up power and get on the plane whilst chucking out loads of heavy black smoke. But when it does get on the plane the turbos quickly spool up and the smoke clears and she marches on to 30 knots no problem. Anybody got any thoughts to what could cause this

 

[volvopaul]

31s always do, I bet at the start of the season when the boats clean and light shes pops up on the plane no problem.

The reason they lag behind is the turbo doesnt spin up till nearly 300rpm, below that theres little torque there.

If the boats heavy and a real problem try the next size down props if you get hold of some to try.

Im presuming all is well with both engines, ie fully serviced etc.

 

[gery w]

cheers paul sounds about right the boat was fully serviced two months ago tanks drained and cleaned all filters changed new volvo exchange injectors new elbows and crank breathers, the only thing i could see is the air filters look grubby again due to being so close to the breathers so might change them would prefer a k&n type filter though are these available for the ad31? volvo ones are a rip off

 

[Pendana]

My old Sunfury had AD31's and had exactly the same symptoms. I cleaned the gunge out of the aftercoolers (very oily) and replaced the o-rings on the pipe between the turbos and the aftercooler which stopped the black smoke.
It still took it about 20 seconds to climb over the hump between 2500rpm and 3000 rpm, but then would rocket up to 4000rpm and 28 knots.Could then throttle back to about 3300rpm and do 20 knots all day. Just lacked that bottom end umph!

Eddie

 

[gery w]

cheers ill have a look at the aftercoolers as well any tips on how to go about it would be much appreciated

 

[volvopaul]

cheers paul sounds about right the boat was fully serviced two months ago tanks drained and cleaned all filters changed new volvo exchange injectors new elbows and crank breathers, the only thing i could see is the air filters look grubby again due to being so close to the breathers so might change them would prefer a k&n type filter though are these available for the ad31? volvo ones are a rip off

Yes thats just reminded me.

I travelled 200 plus miles to a boat once that had similar probs, the air filters were jet black with oil from the breather filters, removed filters for a quick test and away it went.

I can supply non genuine air filters.

 

[gery w]

hi paul how much for the filters? can you get k&n washable type?