Engine puzzle

[Mr Wolf]

Hi, looking for some ideas from the esteemed panel who frequent this forum:

My friend has a Bavaria 32 sport fitted with twin Volvo D4 210's which normally let the boat travel at up to 35 knots.

He went out a little while ago on the admirals cruise and because they were in convoy had to go slow and everything seemed normal. On the way back he put the throttles down and the engines would not rev beyond 1700prm and even then it took some time for them to get there. Suspecting blocked fuel filters (this had been the cause before) he booked the boat in for an engine service.

The next time out the engines would still not pull any revs. Suspecting water in the fuel, all filters were removed and checked for signs of water (none) but put some new ones in anyway and the tank inspection cover removed and siphoned some diesel from the bottom of the tank (less than a jam jar full of water extracted and diesel looked clear). Diesel treatment was added and the tank top up with fresh diesel.

Tried the boat again - this time I went with him and can report: The engines sound 'soft' as if the fuel is very bad quality or it can't get enough fuel through. With WOT one engine will rev to about 1700rpm and the other will slowly rise to 2000rpm.

We anchored in half acre creek, lifted the out-drives and spend an hour giving them a clean before trying the boat again - this time we saw some improvement and although the engines sounded soft the revs did slowly go higher and our max speed increased from 10 knots to 18 knots so we assumed barnacles as the problem. Boat was removed from water, barnacles removed, anti fouled put back into water and the results are still the same.

I am running out of ideas. Can anyone on here point us at some other things to look at?

Thanks

Richard

 

[sarabande]

Trim angle ?

Exhaust blocked ?

Waterlock collapsed or blocked ?

Do the engines rev freely in neutral ?

Air intake filter blocked ?

Fuel tank breather blocked ?

What's the colour of the exhaust smoke 1) under load when warm 2) when starting ?

real wild card: props changed ?

Boat laden down with extras ?

 

[aquatom]

I would suggest you get the Vodia computer plugged in and check out the boost preshure readings. Volvo have had problems with the boost preshure sensors giving pow readings there for the evc system won't inject enough fuel.

I would think that the problem is with the engine that only gets 1700rpm. What revs will they pull one at a time under load?

 

[Mr Wolf]

Thanks for your suggestions.

Trim angle ? - No. He has owned the boat for 5 years and is familiar with how it should behave.

Exhaust blocked ? Good point - will check

Waterlock collapsed or blocked ? - will check

Do the engines rev freely in neutral ? Yes but they are restricted by eng management.

Air intake filter blocked ? No. New filters and ran with them removed with no difference.

Fuel tank breather blocked ? Would the engine not behave normally until pressure in system had built up?

What's the colour of the exhaust smoke 1) under load when warm 2) when starting ? Exhaust smoke is very little and does not change colour.

real wild card: props changed ? - No props are original spec.

Boat laden down with extras ?- Afraid not.

Regards Richard

 

[Mr Wolf]

I would suggest you get the Vodia computer plugged in and check out the boost preshure readings. Volvo have had problems with the boost preshure sensors giving pow readings there for the evc system won't inject enough fuel.

I would think that the problem is with the engine that only gets 1700rpm. What revs will they pull one at a time under load?

Thanks for your reply. Yes the boat is heading back to the Volvo engineers because it does not look like a simple one.

The port engine will not rev above 1700rpm on its own and the starboard will pull just under 1900rpm on its own but will go to 2200rpm when both running. The port struggles to 1800rpm on its own.

Regards Richard