Volvo Kad 300 revs dips on acceleration.

[malta kad300]

I have just bought a Cranchi Smeraldo 37 with 2 kad 300.
After I go out of port for about 12 mins at 1000revs then I accelerate to 3100rev. One of the engines always dips down to about 2100 - 2500rev, for about 3 or 4 times in 3 mins, after it will be stable for 3100 for the whole trip. After few hours and start engines and accelerate to 3100 again it will make the same issue. I am lost and need your help. Any suggestions please .


Horace

 

[mnm-jkk]

Horace Hi,
This is fairly common on these engines as they get older, it is the Turbo exhaust housing having too much wear/corrosion. I had exactly the same thing on both my KAD 44's. Either you replace the exhaust housing or the turbo complete, usually small difference in cost.

John

 

[Portofino]

Sounds like the piont where the supercharger ( kicks in at 1400 prm -turbo takes over @ 2600 rpm ) is not quite synchronised ?
Eventually gets there - but 2100 rpm is a bit low for a dip -check belt tension + clutch activation of the supercharger .
As mentioned above could be sooted up turbos - in which case " cane it " for a few hours

How old ?
How many hours ?
Periods of inactivation ? No good for these -they feed on good blasts