One D12 under-performing (I think)

Nick_H

Nick_H

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I suspect I have an issue with my port engine, D-12 715hp, 2004. Symptoms are:

1. On a 5 hour cruise at 20-22 knots I'm pretty sure I could see a feint witness of black smoke from the port exhaust that couldn't be seen on the stbd side
2. There was a sooty deposit on the transom that I haven't previously suffered, which was biased towards the port side
3. Fuel gauges were equal when we left, port tank showed 1/8 lower than stbd on arrival, although the fuel gauges are a bit temperamental and sometimes move 1/8 of a tank in a single step, so I can't be sure on this.
4. Port engine tacho rises a little more slowly when both throttles pushed to the stops and the turbos kick in

Temps and oil pressures are normal, air filters new and clean. I didn't think to open the throttles up to see what rpm each engine would reach at WOT.

Any thoughts on what I should be checking, or tests I can run to try and identify the issue?
 
I would imagine the first port of call would be a man with a vodia and a sea trial as opposed to guesssing it.

I had soot on one side after a. long run. Call Volvo. Dare not move the boat. Nothing. Suspect it was the breeze pushing soot on one side and off the other.

Vodia gives all sorts of data.
 
Sounds like too much fuel from at least one injector .
I would not WOT it. In fact give it an easy life .
Test -- injectors then the electrotwackery that controls them , i,am not familiar with the vodia Dx tool ,so hopefully a Volvo guy will come along and explain more ,if that tool could Dx the issue ?
Do you have water in fuel alarms ? --- thinking water may make them stick open ,let too much fuel in ?
 
The best start would be to check and compare engine data between the port and starboard engines at intervals of 200 rpm. I believe that basic engine data should be shown at a display.
 
Nick_H said:
3. Fuel gauges were equal when we left, port tank showed 1/8 lower than stbd on arrival, although the fuel gauges are a bit temperamental and sometimes move 1/8 of a tank in a single step, so I can't be sure on this.
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Apologies if my memory fails me, but aren't your engines electronically controlled?
If so, you should be able to see the fuel burn in real time in your displays, which is obviously much more accurate than looking at the tanks.
Did you also check if the engines were running at the same load, when spinning at the same rpm?
Another interesting number to check would be the EGT, but I'm not sure if you get that in VP displays.
Anyhow, I'm with Portofino in not giving the engine an Italian tuning before having investigated further.
I've seen what can happen to a piston after some time, when an injector squeezes more fuel than it should, and it's not a pretty sight.
Not saying that this is surely the case with yours, mind. But I think it's a possibility.
 
Nick_H said:
No display on mine, just a pad with buttons
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Ops, I wrote my comment before reading your post.
Forget what I said, though in your boots I would add the display, if at all possible.
It's a bit of a shame having the possibility and not use it - in fact, I wonder what they were thinking at Princess, when they decided not to fit it as standard...

PS: hang on a minute.
On 2nd thought, isn't instantaneous fuel burn and % of load visible also with the pad, fiddling a bit with its buttons?
Can't remember for sure, it's been a while since I helmed a VP powered boat...
 
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Well, then the only option left to get scientific diagnosis is to get the Volvo mechanic there and connect his computer...
 
volvopaul said:
Nick , is this the same engine that had the seized turbo a few years back ?
Click to expand...

Good memory Paul! If it's the issue I think you mean then no, that was the stbd engine, and the turbo just required turning by hand and a spray of WD40 to free it up. That issue hasn't repeated itself since. The port turbo is definitely kicking in, so it isn't completely seized, but it may not be operating as it should. Thinking about it, the engineer last year did mention that the turbo blades were a bit oily, but ran out of time to clean them, and anyway didn't think it would have any effect on performance. He suggested having them cleaned at the next service. Could this be having an effect?

Something else that may or may not be relevant, I had a stbd exhaust elbow leak two years ago, and the stbd engine sucked soot through the air filter and lined the air side of the intercooler. That was stripped and cleaned last winter, but the port air filter was much cleaner (as it was further from the leak) so I didn't have the port intercooler stripped in the same way. Maybe I should get that stripped and cleaned.
 
Nick_H said:
the engineer last year did mention that the turbo blades were a bit oily, but ran out of time to clean them
Click to expand...
If you don't mind me asking, oily on the aspiration or exhaust side?
And if the latter, could he see it because you had to detach the exhaust for some reason?
While usually the aspiration side can easily be checked just removing the air filter, I'm not aware of any easy way to check the exhaust side of the turbine...
And afaik, oil in the exhaust should create light blueish rather than black smoke, anyway.
Anyhow, surely P knows better - looking fwd to hearing his thoughts!
 
Inlet side. I assume any oil on outlet side would be burnt off anyway. Engineer was only suggesting removing the air filter and wiping the inlet blades with a cloth.

I did actually get to look at the outlet blades on both engines when I changed the elbows. They were quite sooty, but I didn't attempt to clean them for fear of knocking debris back down the hole. I also seem to remember being told not to mess with them, but can't remember by whom. It's not a huge job to access them if I have to by removing the elbows again.
 
Just out of curiousity .... How often shall you check fuel injectors in Volvo diesels ? - Do you leave them unattended until you find out one engine sips more than the other or how ? - That could be difficult if you run one engine only.... Just checked the manual and I do not see anything on this why this question ....
 
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