Question for the diesel engine specialists

[Deleted User YDKXO]

So, even if I was never going to use the top revs, the difference would annoy me and I'd keep going to final resolution.

+1 I'm the kind of OCD owner that likes to know that every system on my boat is in perfect working order and that difference in max rpm would irritate the hell out of me even if I never used the engines in that rpm range

 

[5teve]

I didn't see it mentioned but having been though a similar thing trying to get throttles lined up ( adjusted throttle cables arms, routing etc) I was advised to check the tachos, turned out my port one was over reading by up to 400rpm, fortunately I could adjust it so with a laser tach I adjusted and both throttles lined up.. just a thought if it wasn't resolved

Steve

 

[BartW]

Any developments Bart?

Apologies for not posting the outcome before,

In spring 2017, the MAN service guy in Montenegro (Ilko) has send both injection pumps to a Bosh service center in Zagreb
That one has a better reputation than the ones used before in Belgrade (Serbia) and Koper (Slovenia)

With the people in Zagreb that was the first time there was some communication with me, they were asking questions such as:
- Which pump was the better one, and how much RPM we achieved with that one exactly.
- They also noticed that the pumps were set to run at only 6 cylinders at idle, and proposed to run at 12 at idle (a bit more smooth running)

When the pumps came back, we noticed (had the impression) that many more screws had been opened and now secured again with yellow paint, …
They replaced again more parts in the pumps (no details about that), and provided some test data sheets with each pump.
After reinstalling the pumps, sea trial: both engines achieved just above 2300rpm.

PROBLEM SOLVED.

That was just a few weeks before our travel from Montenegro to Italy Polignano, and later on to Amalfi coast,
I have to admid that we didn’t run long periods at planning speed during that long trip nor in summer 2017 hols, in order not to punish the engines too much.

In spring 2018 after leaving the yard (6 months on the dry) we did another test at planing speed and WOT, and reached again 2300 rpm
then we sailed to Sardegna and spend all summer 2018 in the north in costa smeralda region.

Last summer, on each occasion that we sailed more than 30minutes at planing speed, we had a leak in the fresh water cooling cirquit on the P engine (3 occasions so far) and did quick temporary repairs,
Last November we replaced a few old rubber hoses on that engines from the cooling cirquit (they had probably been overheated before the rebuild)

apart from these leaks, I think both engines are fine now.

Thanks all for the additional comments and advice,
Some of them very useful for future tests

 

[NormanB]

Apologies for not posting the outcome before,

In spring 2017, the MAN service guy in Montenegro (Ilko) has send both injection pumps to a Bosh service center in Zagreb
That one has a better reputation than the ones used before in Belgrade (Serbia) and Koper (Slovenia)

With the people in Zagreb that was the first time there was some communication with me, they were asking questions such as:
- Which pump was the better one, and how much RPM we achieved with that one exactly.
- They also noticed that the pumps were set to run at only 6 cylinders at idle, and proposed to run at 12 at idle (a bit more smooth running)

When the pumps came back, we noticed (had the impression) that many more screws had been opened and now secured again with yellow paint, …
They replaced again more parts in the pumps (no details about that), and provided some test data sheets with each pump.
After reinstalling the pumps, sea trial: both engines achieved just above 2300rpm.

PROBLEM SOLVED.

That was just a few weeks before our travel from Montenegro to Italy Polignano, and later on to Amalfi coast,
I have to admid that we didn’t run long periods at planning speed during that long trip nor in summer 2017 hols, in order not to punish the engines too much.

In spring 2018 after leaving the yard (6 months on the dry) we did another test at planing speed and WOT, and reached again 2300 rpm
then we sailed to Sardegna and spend all summer 2018 in the north in costa smeralda region.

Last summer, on each occasion that we sailed more than 30minutes at planing speed, we had a leak in the fresh water cooling cirquit on the P engine (3 occasions so far) and did quick temporary repairs,
Last November we replaced a few old rubber hoses on that engines from the cooling cirquit (they had probably been overheated before the rebuild)

apart from these leaks, I think both engines are fine now.

Thanks all for the additional comments and advice,
Some of them very useful for future tests

I am pleased to hear this, I think the first people did a rather perfunctory job on the pumps.

 

[Jim@sea]

Is it worth swapping the rev-counter dials just to see if its the dial which is giving a different reading,

 

[NormanB]

Is it worth swapping the rev-counter dials just to see if its the dial which is giving a different reading,

No but it is worth reading the whole thread to fully appreciate what was in play. ;-)

 

[Assassin]

I am not familiar with your engine or fuel pumps.

Well the fuel pump calibration that should have been done at the Bosch facility is part the issue

Of course there is always a tolerance on these things +/- 'something' and I would have thought you would have received the calibration charts for both pumps. On the face of it we are talking 5% difference at top end - what is the difference at idle?

Is it possible the pumps were delivered to the test and calibration facility at different times? Or the facility was not aware these pumps were for the same installation. I would have thought that if they were aware then they could, within the permitted tolerances, provided a better outcome.

I would demand the calibration charts (which should show fuel pumped per element throughout the range) otherwise demand that it (the calibration) is redone.

The other part of the issue is the the on engine setting of the fuel racks and I would have thought there would have been some adjustment - of course you need absolute confidence in your instrumentation (tacho) to ensure you have equal idle and top end condition, but as you say the low performance follows the pump.

If it was on my dollar though I would probably leave it as it is. 5% at top end is not going to have much impact on speed through the water.

Bosch calibration is 1% or less on current test rigs.