Volvo Penta AD41 power issue

[Scarborough]

Hi,
Had this boat for a year now. Bought it in Sydney tested it and it run beautiful, lots of power. Trucked it up to Brisbane and noticed that port engine did not have the same power. Still managed to get to 3500 revs but only after I had the starboard engine at 3700 then pulled it back to 3500. This was ok and I managed to get by but then it got worse and I could only get to 3000 revs. I noticed the water separator filter had black fungus. By recommendations I bought fuel doctor additive and shocked treated the tank (1 common tank for both engines). Seems like the fungus is gone but still revs at max 3000. Note that bottom is clean and props are new as I got recommended to re prop by a local marine "engineer".

Checks done to date.
- engines serviced
- legs serviced
- turbos both spin freely and as far as I can see looks ok.
- back flushed both fuel lines from engine intake back to tank (saw another post suggesting it might be nets on the pickup pipes that were clogged)

There is no black or white smoke at all except for some white smoke on startup for a very brief time. Worth mentioning is that when sitting on the plane at 3000 I can pull back the throttles to half BEFORE any reduction in power?? Both engines revs to above 4000 in neutral, I know that doesn't mean anything but I have also been told by a marine "engineer" they are in good condition.

Thoughts,
I am thinking fuel issue, after trucking up to Brisbane some marine growth got lose and got partially jammed somewhere to the port engine. The two pickup lines are on the tanks bottom port side. After the shock treatment the fungus is gone but maybe the residue of an old tank from 1985 is still clogging the lines? The other issue could be turbos dead but from what I am reading the would show as getting black or white smoke and I can still hear the turbos kick in at 2500. It just feels like the throttles only gives me half the power, could it be the smoke limiter membrane broken or not adjusted correctly? These engines were installed in 1997 and have only done 580hours and still have the Volvo seal on the pumps.

At this stage I am at a loss and using the boat for offshore fishing with my son is out of the question until resolved. Please let me if you you might know what it causing it or test I can do check things.

Cheers
Mr frustrated....

 

[Grub54891]

Re: Volvo Penta AD41 power issue

Engine serviced,did this include the fuel filters?

 

[alldodge]

Re: Volvo Penta AD41 power issue

Hi,
Had this boat for a year now. Bought it in Sydney tested it and it run beautiful, lots of power. Trucked it up to Brisbane and noticed that port engine did not have the same power. Still managed to get to 3500 revs but only after I had the starboard engine at 3700 then pulled it back to 3500. This was ok and I managed to get by but then it got worse and I could only get to 3000 revs. I noticed the water separator filter had black fungus. By recommendations I bought fuel doctor additive and shocked treated the tank (1 common tank for both engines). Seems like the fungus is gone but still revs at max 3000. Note that bottom is clean and props are new as I got recommended to re prop by a local marine "engineer".

Checks done to date.
- engines serviced
- legs serviced
- turbos both spin freely and as far as I can see looks ok.
- back flushed both fuel lines from engine intake back to tank (saw another post suggesting it might be nets on the pickup pipes that were clogged)

There is no black or white smoke at all except for some white smoke on startup for a very brief time. Worth mentioning is that when sitting on the plane at 3000 I can pull back the throttles to half BEFORE any reduction in power?? Both engines revs to above 4000 in neutral, I know that doesn't mean anything but I have also been told by a marine "engineer" they are in good condition.

Thoughts,
I am thinking fuel issue, after trucking up to Brisbane some marine growth got lose and got partially jammed somewhere to the port engine. The two pickup lines are on the tanks bottom port side. After the shock treatment the fungus is gone but maybe the residue of an old tank from 1985 is still clogging the lines? The other issue could be turbos dead but from what I am reading the would show as getting black or white smoke and I can still hear the turbos kick in at 2500. It just feels like the throttles only gives me half the power, could it be the smoke limiter membrane broken or not adjusted correctly? These engines were installed in 1997 and have only done 580hours and still have the Volvo seal on the pumps.

At this stage I am at a loss and using the boat for offshore fishing with my son is out of the question until resolved. Please let me if you you might know what it causing it or test I can do check things.

Cheers
Mr frustrated....

You started off with stating the boat had lots of power then after moving the port did not have the same power. Your not getting black smoke so things sounds good. Are you sure it is loosing power or is it the tach that is telling you? Most diesel tach's uses a square wave generator of such which sends the signal to the tach and they mess up quite often.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi Grub1/2,
Yes it did, I changed them this weekend again.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi Alldodge,
Yes I am fairly certain. Reason is that when I run the boat down in Sydney once reducing the throttles an immediate response was noticed on the engine power, now I can reduce it down by 50% before reduction in power and it cruises at 15 knots rather than 23 I have had local mech check the tachs and they are off but only by 100revs on the FB and spot on in the cabin.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi all,
I spent the hole weekend boating leaving on Friday cruised for 1h then stayed over night and cruised home the next day, both engines maxed out at 3000 revs. My wife has no problem "muching" along at 15 knots but it is VERY frustrating when I know she can cruise beutiful at 23 knots. On Sunday we went/muched over to Moreton Island and it took us about 1h there and 1 hour back, still same max revs. Then something interesting happend that evening, coming home from a Christmas cruise in the canals with the family and pushed down the throttles and starboard engine continued to roar after reaching 3000 revs and pulled out at 4200 as I then quickly reduced her down to 3700. Starboard engine was just flying, just like the time I tested her in Sydney the first time, wow. Now I just need to figure out why, fuel blockage suddenly cleared? Thinking of switching the feed and testing if port engine will come alive and starboard slow down again.

Thoughts?

 

[alldodge]

Re: Volvo Penta AD41 power issue

Hi all,
I spent the hole weekend boating leaving on Friday cruised for 1h then stayed over night and cruised home the next day, both engines maxed out at 3000 revs. My wife has no problem "muching" along at 15 knots but it is VERY frustrating when I know she can cruise beutiful at 23 knots. On Sunday we went/muched over to Moreton Island and it took us about 1h there and 1 hour back, still same max revs. Then something interesting happend that evening, coming home from a Christmas cruise in the canals with the family and pushed down the throttles and starboard engine continued to roar after reaching 3000 revs and pulled out at 4200 as I then quickly reduced her down to 3700. Starboard engine was just flying, just like the time I tested her in Sydney the first time, wow. Now I just need to figure out why, fuel blockage suddenly cleared? Thinking of switching the feed and testing if port engine will come alive and starboard slow down again.

Thoughts?

Some setups have more then one fuel filter in line, buddies Carver had on under the deck he never knew about. Either way I don't see a clog clearing and then come back. Check that you are getting full throttle at the injection pump, maybe the cable is slipping. Check intake fittings for air leaks, a boost gauge would help. Take the air cleaner off and see how it operates, filter may look fine but have an issue. After figuring this issue out probably do need to increase prop pitch and get it down around 3900.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi again AllDodge and thanks for your feedback,
Yes I do have two fuel filters, first one is what I refers to as a water separator (glass bowl with a small filter) then a fuel filter sitting on the engine just before the injector pump, both are recently swapped for both engines. Yes you are right re the prop pitch, one of those tests on the path to recovery. Got recommended to reduce the pitch because the tech told me these boats are under powered so I bought a new set of 4, more $$$ but it helped to get me around. Went from a A-5 to an A-4, setup. In hindsight A-5's are the best choice.

I actually took off the air cleaners for the weekend just to test and I didn't notice any difference

Will check the throttle for the port engine too. One thing that I have forgotten to mention is that during the trip from Sydney to Brisbane the throttle setup on the FB we believe hit a bridge and snapped off, wouldn't hear about it but they were both broken off on arrival. I was concerned that that was the reason for the low power but the marine mech checked the throttles once replacing them and he said they went all the way. I can imagine that the impact would have been pretty severe and I was worried that that might have caused an issue for the pumps internally but as I managed to get 35-3600 revs in the beginning I didn't care. Maybe the pump did suffer some damages. Is there a way to check on diesel pumps if they "open fully"?

Cheers

 

[alldodge]

Re: Volvo Penta AD41 power issue

I don't see an issue being internal to the pump, this looks more external. With the engine off have someone move the throttles full forward while you watch. Once full forward see it there is any play in the pump lever, it should be pretty solid. Mark the location of full throttle. Remove the cable from the pump lever an see if you can move it further.

I take it the engines respond the same from the main and FB. Do you know if you have parallel or series control setup?

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Yes, tested from both throttle locations. Both locations opens the throttle to max down at the pump. I even had the mech down with the engine during one of these tests and he did not see anything wrong. Will check again just to be 100%.

 

[alldodge]

Re: Volvo Penta AD41 power issue

Symptoms are:
Low power
No black smoke
Injection pump going full open
No restrictions on air intake system and no leaks
Turbo pressure unknown but appears to be spooling up

I'm going with it is a fuel issue. If the fuel is not real old then the next thing is to determine if the lift pump is supplying sufficient volume and pressure (860320 pump 14.7-27.5 Kpa). Take the return line off and blow it out, install clear tubing in the return line and run it. If you have flow and pressure and still low power will need to go to injectors then the pump

 

[Scarborough]

Re: Volvo Penta AD41 power issue

You made me think of air when you mentioned above checks. I have only checked air filter not the charge air cooler for leaks or blockage. I thought if it was an air issue it would result in white or black smoke? I think you are right though about the fuel issue. To close off the potential issue of the fuel pickup I am putting a 20l jerry can in the back and connecting it directly to the lift pump. If that doesn't change anything I will wait for the pressure gauge I have ordered to check the fuel pressure. Both engines only have 700 hours on them so I am hoping the injection pump or injectors don't need a recondition, yet.

Thanks for suggesting the order, I would have gone pump then injectors and that could have been costly if it just turns out to be dirty injectors.

Will keep you posted on the progress. Thanks again all for your suggestions.

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

my first thougt is fuel related. anythime you have algae in your fuel system the ONLY way I know of to cure it is to clean everthing from one end to the other (and not simply adding an algaecide). that crap got into everything, plugged all the filters, and probably did a number on plugging the filter heads, etc.

most aditives kind of kill the algae, then you have dead algae floating around and plugging stuff up again and again.

there are mobile fuel polishing services if you have a large amount of fuel to scrub.

 

[K-2]

Re: Volvo Penta AD41 power issue

At this point, if it were my boat I would rig up some kind of totally separate fuel tank / lines. A drum of fuel on deck with new fuel lines, by passing the water separator and just going through the one fuel filter. Let the returns go back to the tank as it does now.
This way you are eliminating all the pieces of your existing fuel supply. Give it a good test ride and if the engines run great you know
where the problem(s) are.
Are these engines after cooled ?
A friend of mine has a AQAD41A, it was down on power and RPM's , turned out to be the head gasket, no other symptoms , I would have never guessed head gasket.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi,
I am ordering two turbo pressure gauges but can someone confirm the expected turbo pressures?

Boost @ 1800 rpm = 4.3 psi
Boost @ 2500 rpm = 11.6 psi
Boost @ 3250 rpm = 17.4 psi
At 3800 revs?

Cheers

 

[alldodge]

Re: Volvo Penta AD41 power issue

Can not say for sure but I have found the same readings. So a 0-30 should work out the best.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Ok, haven't got the turbos yet but I did remember that when I purchased the boat it had Fleetguard FF167A that has a flow rate 75 liters/hr 12 microns at 98% and 10 microns at 92%. I bought new Volvo original filters (3581078) when I first got it on recommendations from our local Volvo dealer. However, I can't find any data on flow rate, are the good enough? Anyone good the technical datasheet showing fuel usage curve with revs and torque?

 

[alldodge]

Re: Volvo Penta AD41 power issue

Don't get it with Volvo Penta but finding data sheets have been an issue. All I can say is the other manufactures state they meet or exceed that of VP. I would say VP filters should be more then adequate for the engine. Most of the filters have always been able to supply more then the engine needs until they get more then 30% restricted.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi all and sorry for the late update.
Ok, I finally managed to rig up two separate 20l Jerry cans with clear hoses. The result was the same as before (just getting to 2500 revs, no black or white smoke, engines run and start smoothly) but when we were out testing it we noticed that if I quickly pull the throttles back to 0 and stop then full throttle again we had more power for a little while. I could also see some air in the in lines on both engines, this is really weird as the fuel is taken from one new hose (<1m) no air leaks but I still couldn't manage to get rid of the air even though we pumped and pumped the lift pumps. In the process of elimination I have now ordered 2 brand new lift pumps as they are cheaper than reconditioning the two injector pumps

See if you agree with me on this one, since we noticed a clear difference if I quickly pulled the throttles back to 0 then full throttle again there is a fuel supply issue. Pulling back the throttles to 0 would halt the fuel flow to the injector pump and the lift pump would still work since the higher revs would still go for a little while until back down to idle => higher pressure to the injector pump when I push for full throttle, or?

The other thing could be that something has to be adjusted on the injector pump like the smoke limiter settings?

Cheers and thanks again for the support.

 

[alldodge]

Re: Volvo Penta AD41 power issue

After your latest test I'm leaning more to an injection pump (IP) problem. Your narrowing it down but I don't see the need to replace both lift pumps. Your starboard is doing fine and the issue is the port side. Agree the IP does cost quite a bit to have it looked at. The lift pump supplies fuel at a constant pressure to the IP and what is not used is sent back to the tank. The pressure is controlled by the lift pump and the bypass valve on the IP. In stead of replacing the lift pump, swap the pumps. If it moves then you have the fault.