Volvo Penta AD41 power issue

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi all,
Ok, both engines maxed out at 2500revs. This has slowly been going down from 3700 for starboard and 3500 for port. On the weekend I installed brand new Volvo Penta lift pumps for both engines, still the same, did NOT GET ABOVE 2500 revs, I give up ... To be fair we had 14 people on board (gorgeous weekend and great friends that didn't mind doing 10 knots but not the best environment for testing) this weekend and 2/3 fuel and 1/2 water so I will give her another chance but it felt the same

The weird thing is the engines run so smooth and start easy with no white or black smoke at load.

I have decided to get a bosch diesel mechanic out here next, I can't for the life of me find what the problem is and I am hoping he can either tell me if it is the injectors or the IP or a Turbo issue, weird is that it is the same for both engines.

Cheers and thanks again for all the threads and support to date

 

[K-2]

Re: Volvo Penta AD41 power issue

I am unclear on how severe your algae problem was/is?
Did some get by the filters and get into the fuel injection pump and cause problems?
The NO SMOKE leads me to believe it isn't injectors, personally I have never seen bad injectors that didn't cause some color of smoke .
Same with the turbos / boost . Did you ever get boost readings?

 

[alldodge]

Re: Volvo Penta AD41 power issue

Now that you have both engines doing the same it has to be fuel supply. I don't see bad anything other then fuel restrictions or bad fuel. As K-2 mentioned start again with fuel filter checks, or as Scott mentioned have your fuel cleaned. Have the fuel test for proper cetaine rating, and/or find out if where your getting your fuel has had problems. Both engines are doing the same thing, it has to be a fuel supply issue.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi all,
I will check and swap all the filters one more time. Keep in mind I did put two completely separate tanks with diesel from a "normal" petrol station and it made no difference at all. I also sat down with the local marine engineer today and he is as confused as me but suggested I'd take her out more time without the extra 14 people on-board, fair request. Then he suggested the following before pulling off the injector pump as I at this stage do not believe it is a Turbo issue or compression issue:

- Injector pump timing (if that is wrong you will not get the power when you need it I guess)
- Tapper check, to make sure they allow the correct amount of fuel in and out

I will also mount the two turbo gauges I bought on Friday before I take her on a test run again.

Will keep you posted on the progress because this has to be resolved once and for all and I hope this thread will save people the headache I have had to date

Cheers,

 

[K-2]

Re: Volvo Penta AD41 power issue

Good luck man, I hope your nightmare is over soon. (and cheap)

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Ha ha, thanks. Yep thank goodness boating is my "hobby" not my livelihood. Anyway managed to get out on the weekend to try out the turbo pressure gauges I installed during the week.

At 700 revs we had 0-PSI
At 2000 revs we had 2-PSI both sides
At 2600 revs we had 5-PSI both sides, this was flat out...

To me this still seems like a fuel delivery issue because there is NO white or black smoke, at all and the turbos spin freely and has no moment sideways at all either. Also noting the temp cruising at 2600 revs for an hour is sitting just under 80dgc so the engines aren't working hard.

So next step is to get the bosch diesel mechanic out here next week I am guessing.

Cheers and happy boating, will get there in the end, I hope

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

with the low pressure, it is either a bad wastegate, or your turbos need a rebuild

 

[alldodge]

Re: Volvo Penta AD41 power issue

Ha ha, thanks. Yep thank goodness boating is my "hobby" not my livelihood. Anyway managed to get out on the weekend to try out the turbo pressure gauges I installed during the week.

At 700 revs we had 0-PSI
At 2000 revs we had 2-PSI both sides
At 2600 revs we had 5-PSI both sides, this was flat out...

To me this still seems like a fuel delivery issue because there is NO white or black smoke, at all and the turbos spin freely and has no moment sideways at all either. Also noting the temp cruising at 2600 revs for an hour is sitting just under 80dgc so the engines aren't working hard.

So next step is to get the bosch diesel mechanic out here next week I am guessing.

Cheers and happy boating, will get there in the end, I hope

Agree, if you were burning more fuel the boost would increase. At 2600 your not turning enough rpm to spin them up. I'm still thinking throttle linkage, or something which controls both engines. It's like give both engines 1/2 throttle, they both are running great, they just are not going WOT. Need a good diesel guy there, and hope he/she knows there stuff.

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

AllDodge, the OP's turbos should be putting out about 12psi at 2600 RPM. he is only reading 5psi. so he is down on boost, which is down on power.

im willing to bet the EGT's are also high (low boost and trying to fuel)

 

[alldodge]

Re: Volvo Penta AD41 power issue

Scott, I would agree with that if there was some kind of black smoke (high fuel, low boost), and if it was not effecting both engines. Original post was one engine was running low rpm, then later the other started. I actually hope your right, waste gates and turbos cost less then injection pumps.

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

I lost a boost hose on a Cummins powered dodge when I was trying to out-run a tornado when hauling my '48 chevy back from Minnesotta one time. truck fell on its face, and there was not much black smoke visiable from the tail pipe that I could see in the rear view mirror.

EGT's shot up though and I warped the exhaust manifold enough to spit the gaskets.

If I was not directly in the path of the tornado, I would have pulled over. 20 minutes to repair the slipped hose and clamp would have been much cheaper than $600 for a new exhaust mani and gaskets.

Marine engines have water cooled exhaust, so the chance of warping is minimized, and with the water cooled exhaust, you wouldnt notice much if any black smoke.

 

[K-2]

Re: Volvo Penta AD41 power issue

I had no problem seeing black smoke on my previous boat with a water cooled exhaust 41P,,,neither did the buyer:blue:
What does it rev to now in neutral? Both engines still 4,000 like before or has that RPM also dropped?
Seems like it was 1 engine, now it's both? Are turbo problems contagious? Fuel problems could be ,with 2 engines and 1 fuel tank.
Does this engine have a waste gate? Not all 41's do.
No smoke
No vibration? Both engines run perfect except lacking upper RPM's?
I also keep thinking controls are not giving full throttle but that seems to have been thoroughly investigated more than once.

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi guys,
Thanks for all the feedback, much appreciated.
Ok, I managed to mount the new turbo gauges last week before we got out on the boat on Saturday. Results were not that good, got the following results:
- 2000 revs = 2 PSI
- 2600 revs = 5 PSI for both engines, (full throttle)

It is just like the throttles doesn't open all the way. Could it be that the throttles have been getting worse after hitting the bridge getting her up to Queensland? It sure does look like a fuel issue. At this stage any suggestion is welcome as spending more money on "hunches" by "marine engineers" is a bit dated.

Cheers and happy boating all,
I am sure I will get there in the end

 

[alldodge]

Re: Volvo Penta AD41 power issue

Hi guys,
Thanks for all the feedback, much appreciated.
Ok, I managed to mount the new turbo gauges last week before we got out on the boat on Saturday. Results were not that good, got the following results:
- 2000 revs = 2 PSI
- 2600 revs = 5 PSI for both engines, (full throttle)

It is just like the throttles doesn't open all the way. Could it be that the throttles have been getting worse after hitting the bridge getting her up to Queensland? It sure does look like a fuel issue. At this stage any suggestion is welcome as spending more money on "hunches" by "marine engineers" is a bit dated.

Cheers and happy boating all,
I am sure I will get there in the end

What ever it is, it's something that impacts both engines. I would be a rare for both engines to suffer from, air restriction, turbo failure, injection pump failure and the link. This all started to happen as you said after the bridge thing. I keep going back to throttle linkage because if it was bad fuel or filters, one would go down more then the other. Now you did have one engine doing worst then the other for a short while.

Does your engine have a synchronizer on them, one that can keep the engines at the same rpm? Long shot here

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

I would get a diesel mechanic in there.

low boost and no black smoke can indicate under fueling. this could be dead bio debris from your algae issue in the first post.

you cleaned the lines, cleaned the filters, however did anything make it past the filters and plug the fuel pump or injectors?

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi AllDodge,
I totally agree with you that it would be very rare for both engines to suffer from, air restriction, turbo failure, injection pump failure and the link. As far as I can tell I do not think they have a synchronizer as I in the earlier days had to rev starboard engine to 3700 until port got up to 3500 then reduce the starboard back to 3500 manually.

Scott, I have the Bosch specialist booked for this Thursday so maybe we will see the end of this saga after that

Will keep you all posted.
Cheers

 

[Scott Danforth]

Re: Volvo Penta AD41 power issue

while he is there, have him bump the fueling a bit

 

[K-2]

Re: Volvo Penta AD41 power issue

Scarborough any updates ?

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Hi all,
Sorry for the late reply. I did have the Bosch specialist over last week. We sat down and went through all the tests done to date, in the end he told me we need to get the pumps in for a service He also mentioned that there have been issues with the VE pumps where the membrane pushing the spring loaded pin down when the turbo pressure increases gets stuck (see attached Bosch picture). I pulled both off just to have a look, I must say both was sliding up and down very easy plus had no rubbish around it once I pulled it out, in fact they both looked very clean (see attached photos).



A friend of mine keeps telling me it is the Turbos. The problem I have with that is that there is no smoke but then again if the smoke limiter in the IP is working there wouldn't be any smoke because the pressure on the membrane is not enough to allow more fuel in, aaarg....

Before I pull the pumps off I will take off the exhaust side of the turbo and check if I see anything that doesn't look ok. I have another question, since this setup is using legs and the exhaust is pushed through the legs, could there be a restriction there hindering the pressure to build up?

I was really hoping that having the Bosch guy out here he would test it tell me what is wrong with it happy to send it in but I am reluctant to spend more $$ on a hunch but at this stage it seems like my best option after I checked the turbos.

Will get there in the end, I hope

 

[Scarborough]

Re: Volvo Penta AD41 power issue

Scott, forgive my ignorance but where does the wastegate sit on the 41's, don't think in the turbo, manifold, do they all have it?