New or reconditioned parts

[Mikkelsborg]

What is the general experience with regards to fuel equipment.
Do you always order new, or do you have reconditioning program ?
Any experience with reconditioned plunger and barrels ?

[Big Pete]

I was on one ship before it went into drydock and I prepared a set of main engine injector nozzles for overhaul. I stripped them all down, cleaned them and removed all the gaskets and "O" rings, and tightened them together hand tight, because we had run out of gaskets and "O" rings for them.
I rejoined after docking and was told that they had been sent ashore and overhauled. The main engine injectors were due for overhaul, so I opened the overhauled injectors, all freshly painted injector at the top and dipped in protective coating, tested them on the fuel pump and they worked O.K.
Put them in the engine and ran it up. Fuel leaks every where!!!
Put the old ones back in the engine and stripped down the overhauled ones.
You guessed it, no joints or gaskets and only assembled hand tight. (The only reason they went ashore was because we had run out of gaskets and "O" rings.)
So I would be very wary of getting them overhauled ashore!!!

I would say that although fuel equipment is expensive, so is fuel. It is worth spending the money on fuel equipment to keep the fuel consumption down
Most engine makers no longer reccommend planned changes of injectors on running hours, they now prefer running the injector until you have a high or low exhaust temperature and then scrapping the nozzle.
If the barrel an plunger of a fuel pump are worn, I do not see how you can re-condition it. Plate it and grind it back to original size???
Some fuel pump non return valves could be lapped in if they were leaking.
But most are of the balanced type with a spring loaded non return valve in each direction, so i do not know how on some of them, you could replace the springs, which are the weakest point.

I think overall, I would run the fuel pumps until you have a drop in performance, i.e. reduced peak pressure and exhaust temp for the cylinder compared to the fuel rack position, and then change the fuel pump and dump the old internals.


However, I am sure plenty of people will have different opinions!!

BP.

[JK]

Most of our ships rebuild their own FO pumps and injectors with new parts.
We also use the engine manufacturers to rebuild and set the pumps up.
Expensive, but when I put a generator on the board, I want it to synchronize and carry 100% load.

[Mikkelsborg]

Big Pete - There ia as many supplies as there is fuelvalves (or almost) and every single shop have their own way of reconditioning.
There is different procedure for overhaul of 2-stroke equipment and 4-stroke equipment. I presume from your text that you refer
to 4 stroke equipment. WIth a set of gaskets and o-rings you can get halt the job done. WIth regards to nozzle tips, we normally
recommend replacement as repair is not economically feasible, but however we alway offer the client different tips as there are
many different suppliers world wide. This based on if the engine is EIAPP certified, which narrows down the alternative supplies.
Non return valves and connection pieces (example wartsila 32) is overhauled at very favorable cost, where all springs are replaced.
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With regards to overhaul of plunger and barrels, the plunger is always scrapped and newer reused (Unless clerance are with in limits).
The most used procedure is refurbishment with new oversize plunger after the barrel have been honed clean. (minimum material taken out).
WIth the new oversize plunger you can set the clearance specificly for the specific fuel type used onboard or on application, this be HFO, MDO,
destilat or other. By adjusting the clearance to specific fueltype user gain a longer running period and no leakages. Normally all new plunger and
barrels are supplied for HFO clearance, which already from new provide a reduced lifetime.
Especially on four stroke fuelpumps there is a lot of money to be saved with a reconditioning program, this further serves a part of the environment
proactive approach...

[Mikkelsborg]

This further bring me in to timing and adjustment after overhaul of fuelpumps with regards to X - measurement and protecol.
We have never seen two engines (same type and make) behave in the same way, therefor a timing by electronic indication would
be recommendable. We supported a tug in Norway, which after timing by electronic indication gained +10 tons in pull in comparison
to general factory settings. A success story, but a lot can be done to increase the performance, or lower the fuel expenses..
Very important to check when using mixed fuels (Example new bifuel BC directive)

[Big Pete]

The bad experience I had with the shoreside overhaul of Injectors was about 30 years ago when I was sailing with a Mirrlees "K" Major 4 stroke engine.
It was not meant to reflect in any way on Mikkelsborg's company.

I most strongly agree that correct adjustment of the fuel rack timing and stand out is essential.

The worst case I saw was on an ancient Tanker with twin V12 Pielsticks. This was nearly 20 years ago. I joined in Lagos and sailed for Malta. We had to stop one engine each day to replace failed injectors and exhaust valves and to clean the central coolers which were blocking up with huge quantities of Mussels. With only one engine running the ship struggled to make steerage way, partly because she was 3 feet overloaded and well down by the bow, partly because the entire hull, and we later found the proppeller, were completely covered in Shell fish, several layers deep..
When we eventually limped into drydock, we had all the turbochargers overhauled, all in very poor condition and all the air coolers, nearly choked solid with dirt and the fins worn very thin and bent over blocking the air flow.
All the cylinder relief valves were overhauled for survey on one engine and a few units done.
When we ran up one engine we found all the relief valves were lifting, with the engine de-clutched and running at idling speed. We sent the valves back to the shore workshop for re-adjustment, but they insisted they were correct. We then checked the fuel timing and found that all the fuel pump timings on that engine had been advanced by 15 degrees. I can only assume that this was done in some misguided attempt to lower the exhaust temperatures. Of course, by starting combustion while the piston is still on the upstroke a lot of the power produced was wasted opposing the upward movement of the pistons instead of helping push them down. This obviously resulted in the Governor supplying more fuel to compensate. The end result being that the engine was still running on the maximum exhaust temperature, but being severely mechanically overloaded while producing less shaft power.

We checked the other engine (opposite rotation) and found that the fuel injection timing on that was 15 degrees late...Again I can only assume that the intention was to make injection 15 degrees early, but the "Engineers" who did it, did not realise that the rotation was the opposite of the other engine. So this engine was "afterburning". Pressure was building up after the piston was already going down and combustion was still occurring when the exhaust valves were opening.

Sad to relate there had been British Engineers running the ship since it was built.

Unfortunatly I have come across several " Engineers" since then who believe they do not have to overhaul fuel injectors, so long as they advance the fuel timing and reduce the fuel rack setting each time they have an high exhaust temperature alarm.

I strongly believe that unless you have the Proffessional expertise of the Makers test bed team, or an equivalent independant outfit, you should keep exactly to the iming and fuel rack stand outs in the Test Bed Data Sheets.
Also off course, to any shimming on the con Rod or liner to adjust compression ratio and bump clearances.

BP

[Mikkelsborg]

Big Pete, no problem....
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A lot have happend over the recent 15 years within the reconditionning line of bussines.
I liked to read your input...
Back in Scandinavia the english produced and built engines had a tendency to selfdestruct over time (Often shorter time than TBO).
The v-engine engines is a challenge to do electronic indication on, as one have to set the parameter with angle in the analysing software.
To this date, no two pielstick engines have had the same angles, and when confronted pielstick they were aware of the situation.
Specially when running HFO we recommend to do indication on reference cylinder in order to adjust viscoterm to optimal position in order to secure best performance at all times as per stated in IMO regulations.
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Years back I was a part of teams measuring on two big werkspoor 20TM410 with mak M332 aux's. The problem was with the small engines, which had a turbocharger loss every thee months, besides valves etc etc. At the time it was reported that the fuel quality was not up to operation standard (Marine use) which the owner totally rejected. Two years after DNV had a new testmethod for fuels, and the fuel was (by DNV) recommended for best use in asphalt roads.... Had the owner only thusted the report a lot of money could have been saved... The firing diagram clearly spoke for something wrong.. To make sure we tested with the different and newly calibrated units, all with same result.... It's is not about being right, but get the job done to the clients satisfatory with minimum cost involved (And technical standard goes without saying).