Volvo Diesel power loss

[liberty5]

My KAD 42A was running fine for many months. Suddenly, en route, I encountered a loss of power in the cruising range. i.e. the engine is not able to hold the rpm above 3200. Below 3200 the compressor engages in kick in mode and acceleration is good until disengagement. Sometimes the engine is able to hold the rpm and seems O.K. again, but then drops back after 1 minute, until compressor kicks in again.
Checked turbo, compression, nozzles, props - all O.K.. Changed fuel and air filter.
Antifoul is new.
Can anyone help pls? Am running out of ideas.

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[Cantata]

A couple of suggestions:
An air leak in the fuel system somewhere between the tank and the fuel pump. Doesn't have much effect at low revs, but as suction increases at higher speeds, more air gets sucked in.
Or maybe you have a gauze filter on the pick-up pipe in the tank, and it is nearly completely blocked. At high revs it doesn't let enough fuel through.
Best of luck - glad it's not my engine!

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[boatmike]

Before expounding all the possible reasons for power loss some questions (sorry if some are obvious)

1. Do you have a water temp gauge fitted. If so is the power loss accompanied by overheating?
2. If you take the engine out of gear at these times will it reach max revs easily without misfire?
3. Do you get smoke, if so is it black or white?
4. Is there plenty of oil in the gearbox and is it the right grade?
5. If you take the engine out of gear at these times will the propshaft still rotate freely?
6. Are your engine bearers in good condition and is the engine still in alignment?
(would not be the first time I have seen an engine that moved around and pulled the shaft out of line intermittently)

Sorry about all the questions but if you can answer them it should give a clue. It's always something obvious in retrospect!


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