AQAD30a Down on Power and Noisy SOLVED!

[Slobbit]

Simptoms were:
Diesel knock.
Would not pull above 2000rpm underload but would rev ok without load.
White Smoke.

After performing several checks such as injector timing, compression, Injector condition, fuel filter on engine the problem finally turned out to be the water seperator filter. The filter had crystalised diesel blocking it up, the next step is to drain and clean tanks and fill up with fresh fuel then give both engines a well deserved service as I think the previous owners didn't bother.

This problem has existed on this engine since 2006 I have found a bill that came with the boat for £1600 to have the injector pump rebuilt, written on the bill it states the rebuilt pump had not solved the problem of low power but that either the injectors were worn or the fuel was contaminated. It's a shame the diesel engineer didn't check the filters before he rebuilt the pump.

Just to add to this I found a marine diesel engineer who said he knew all there was to know about these engines so he took a look and diagnosed a sticking valve so the head would have to come off, I had a good laugh after he left the boat and kept with my original idea of fuel starvation. So be warned the cowboys are out to get you!!
A good lesson for everyone check the simple things first.

Thanks to everyone who has commented on the post.

Slobbit

 

[LittleShip]

Good to hear you found and fixed the problem but....

This problem has existed on this engine since 2006 and this was the first time this was checked........ and people wonder why I don't let anybody play with my toys.

Tom

 

[mont]

ditto littleship

Diagnosis is often difficult but this one sounds pretty basic.

Good to hear your down the diy route now and you found the problem.

 

[Slobbit]

I used to work in the motor trade as a mechanic back in the 80's and after seeing some of the work carried out by other mechanic's I won't let anyone touch my engines. I just needed to get my head around the problem and find my way round the engines (not being used to diesel engines) but they're hardly rocket science.
The only thing that does worry me is the cost of the parts on Volvo engines.
Regards
Slobbit

 

[Slobbit]

UPDATE!!
Although the diesel filter has solved the white smoke and noise problem the engine is still down on power and will only reach 2000rpm flat out but now producing black smoke, this is telling me the engine is over proped.
I have had the boat lifted out so I can check the prop sizes and the condition of the legs, both props are A4's and in fair condition with very slight damage not enough to cause a difference of 500rpm between engines.
I decided to check the ratio of the legs, I marked a chalk spot on the engine pulley and a chalk spot on the props. One engine is turning approx 2.5 times to one turn of the prop the other one (which only revs to 2000rpm under load) is turning 2.0 to one turn of the prop which leads me to believe the leg has been changed at some point for one which is 1.95:1 instead of the correct one which should be 2.30:1. So I am now in the market for a 280 DP 2.30:1 leg or the lower gear set.
Slobbit

 

[Slobbit]

Update 2

Boat went back in the water last month, after a couple of hours cruising slowly around the harbour just to bed everything in I took her outside and slowly pushed her up to 3000 rpm on both engines. To my delight she poped up on the plane with little or no effort at about 2600 rpm, I held it to 3000rpm for about 5 mins there were no noises, smoke or strange vibrations.
Problem Solved!!!

 

[moonraker 36]

well worked out..!
glad you got it sorted..

 

[Converging]

Great Result - I know exactly how you must have felt!!!