Need help with diagnostics please . . .

[french44]

so : no over tem, no over oil pressure, no black smoke with dust. it could be an advance problem check the sensor it was a problem on QD32 on 4*4 also the injection solenoid Nissan knows this trouble on 4*4 it's same engine. try to run the engine without load to see if you get more rpm than 3000 may be the cutting injection point is not well adjusted. What is version of engine Mechanical injection ? or other ?

 

[L'eau.Life]

Basic QD32 mechanical injection from 2WD Navara. Engine free revs off the gauge (4000+RPM)
Thanks, Alan

 

[powerabout]

Have you askedgarret if those pumps are capable of pumping twice the fuel at wot than the built spec.
They can only pump max fuel as per their settings
All that fuel is going somewhere?

 

[L'eau.Life]

The pump delivers way more than the engine needs and recirculates the excess. Hoping to get the guy from Garrett to visit the boat - just trying to find a time that works for everyone

 

[Baltic Bandit]

The pump delivers way more than the engine needs and recirculates the excess. Hoping to get the guy from Garrett to visit the boat - just trying to find a time that works for everyone

any chance that you have something binding or off center from the tranny aft?

 

[powerabout]

If its easy job I would swap the injection pumps over
That will solve that question

 

[L'eau.Life]

@Baltic Bandit
Well, we looked at that and I spun the prop by hand when I dived and it turns very freely in neutral. When I select drive both motors drop about the same (100-ish RPM) and there is no evidence of any binding. I've run about 50hrs while this deterioration has been occurring and if it was a significant dragging I would have expected some sort of failure or other indication.
Many thanks.

 

[powerabout]

The pump delivers way more than the engine needs and recirculates the excess. Hoping to get the guy from Garrett to visit the boat - just trying to find a time that works for everyone

Yes but it can only inject to the max fuel setting
Hard to believe that that setting allows twice the fuel of what the good engine uses at full load.
Thats like a pump for a turbo engine delivery full fuel when there is no boost
Volume wise the pump shop should be able to tell you how much fuel that can pump at its correct setting

 

[L'eau.Life]

@powerabout
In terms of access the other engine was definitely "born out wedlock"! It is a major to get to the pump involving removal of the full galley. If it comes to it I'll have to follow that path but in that case will probably wait until winter. At least for the moment the boat is usable and our weather has been stunning recently.
I'll ask the question re pump capacity/flow.
Thanks again!

 

[Baltic Bandit]

@Baltic Bandit
Well, we looked at that and I spun the prop by hand when I dived and it turns very freely in neutral. When I select drive both motors drop about the same (100-ish RPM) and there is no evidence of any binding. I've run about 50hrs while this deterioration has been occurring and if it was a significant dragging I would have expected some sort of failure or other indication.
Many thanks.

So I assume from the access issues that my next idea is not viable - namely to pull the trannies. you could have something on the output bearing side that only starts to show up at higher revs, some sort of binding that is increasing friction and hence transferring more heat back into the engine. though from the amount of heat you describe, it probably would have failed catastrophically before this.

Enjoy your weather. its dreary in Paris and everyone is coughing fighting a nasty grippe that has been going around.... :-(

 

[quequen]

White smoke and overconsumption in a diesel engine is often caused by a damaged fuel pump.
Pump damage often comes from internal oxidation caused by water into the fuel's filters.
Hope it helps, that's what my mechanic says...

-

 

[L'eau.Life]

Thanks quequen - we have had the pump checked and overhauled and changed the filters. No evidence of water. :-(

 

[Westfield 11]

@powerabout
That could however be misleading as the port manifold was repaired a while back.

How long ago was the manifold repaired and what was done to it? Is it possible that this could be your problem?

 

[L'eau.Life]

@Westfield 11
Manifold repair was after the problem started. I've had the manifold off and inspected two weeks ago and no issues there.
Thanks, AB

 

[L'eau.Life]

Manifold repair . . .

This is why - the original welds had no penetration whatsoever and with [probably] 30-odd kilos of steel and water hanging on them, this was the result!
Fortunately when it let go I was tied up alongside investigating the engine problem . . .