Volvo Penta AD41 low rpm at WOT

[SPDauto]

no wastegate on mine, i think il get a boost gauge and monitor it and see what its doing. any easy point to connect a pressure sender on these?

 

[BruceK]

Fitting Charge Pressure Guage kit to KAD42

have a look at Mr Googler's solution in this thread. I put in guages and the wiring was a genuine PITA

 

[Sianna]

Workshop Manuals are here

KAD Series

the files are callled KAD 42 but they cover your engine.

i agree with Bruce…I’d be looking air side. Boost leaks, intercooler needing a clean (although doubt that would stop you at 2.5k rpm unless really bad) or a combo of issues.

defo test the injectors as Kashust said too

Thanks Mr G really useful documents

 

[Divemaster1]

...............
Its running ok at idle and starts with half a turn of the key, but im lacking power. I have no tacho at the moment either but sounds like i am only getting approx 2500rpm at WOT. I do have some vibration under load also which could be a slight misfire, but difficult to tell.

I have checked, cleaned and replaced the fuel lines all the way back to the tank. new filter, new water catch, lift pump removed and checked and is ok.

Turbo has no play and is spinning easily and freely.

Any penta gurus on here able to shine a light on this for me? Injectors out next to be tested or is there anything i can check or clean on the pump in situ?

Check the exhaust bend (where coolant meets the exhaust gases) ... easily gets clogged up by rust etc., and restrictions there will have give similar symptoms ... simple to check and relatively easy to fit a replacement..... but do check that it is above water level before you undo the four bolts...

 

[SPDauto]

its very close to the waterline as far as i can tell.... would be nervous undoing the elbow. Im just eyeballing it from pictures i have but i will check properly when i at the boat over the weekend, and see if i can pull it off safely!

 

[BruceK]

Sorry that would give a temp rise not a rev restriction. It's the raw water injection into the exhaust that clogs up, not an exhaust restriction. Besides you will smell burning rubber if there was a restriction. You couldnt miss it. It stinks. Just put your hand on the rubber after idling for a minute. If the rubber boot is tepid all round you are fine. Any isolated hotspots and you have a mild blockage. When it blocks up it restricts raw water flow hence engine temp rise.

 

[SPDauto]

so, i pulled the injectors last night, they were well in there and took the slide hammer to get them out. Pretty dirty body and tips didnt look great. Left them with a local place to have them tested and refurbished, 5 out of 6 had no spray pattern and were just dumping fuel. Hopefully this is all or part of my issue.

The injector holes in the head are pretty dirty also, anyone any tips on cleaning them up? I see there is a set on ebay for cleaning up the holes and seats, comes with a few wire brushes etc for a drill. Open to suppestions as i have a few days now to get them cleaned and ready to refit

 

[SPDauto]

so, i got the injectors back and re-fitted, slight improvement but that's about it. Still struggles to build revs and unable to get above 7-10kts WOT.

I intend to check the turbo for corrosion next, although even with the throttle wide open at the stops it does not smoke at all, so something is telling me its still a lack of fuel issue, and that I am not making enough revs to get into the turbo range. My turbo elbow is close to my waterline so may have to lift it out to check the condition.

Damn Volvo....

 

[SPDauto]

one other thing i noticed..... i took the top of the smoke limiter to check the rubber part was ok. Its in good condition, as is the pipe to the inlet, but it is adjusted quite far down already. Is this normal? Or has someone been playing around with it? I was of the opinion that the further down the plunger was adjusted, the more fuel the pump can have. I would say its almost adjusted to maximum.

Anyone any knowledge on the pumps they could share? or even a picture of how far in your adjustment screw is set?