Are you experiencing horrendous Wear and Tear to your smaller HFO engines?

There is no doubt that smaller HFO engines  such as W?rtsil? L20, MaK M20, Holeby 16/24, HimSen 17/28 etc. are often subject to increased wear of crankpins compared to their bigger brothers and as a result, at Mark Van Schaick BV we have reconditioned a considerable number of crankshafts from these engines.

If you can bear with me I would like to address some of the factors involved:
Hardness or lack of it. A lot of people refer to this, arguing that Makers dont make them like they used to!  However from a practical point of view there is no significant difference in Brinell (Bh) figures from model to model. Essentially MaK, as with MAN and W?rtsil? are all “soft” shafts with an intrinsic hardness of about 250-280 Bn (as opposed to the hardened shafts that Daihatsu, Yanmar and the Caterpillar produce of about 500-600 Bn).

From the above differences, "soft" shafts can easily be recovered following a thermal event (unless severly cracked) because its a straight forward process, in the specialist workshop, to reduce excessive hard spots by heat treatment. The shaft can thus be returned to you fully classed and ready for further service.

Increased wear rates in these smaller bore engines are more commonly related to higher rotation speeds and the reduced clearances employed.
The critical components are the oil pump, Turbocharger and Crankpins because even very small levels of soot not only increase oil viscosity but the particle sizes act abrasively and can wedge between the moving surfaces. This is also made worse due to very small oil clearances.
Increased speeds of 900-1200RPM also seem a necessary requirement when the Makers want to increase power density.
e.g. The 2nd moment compensator on the W?rtsil? 4L20 runs at 2 x 900 (1800RPM) and as a consequence there have been many oil quality related failures. Mark Van Schaick has reconditioned many sets of compensator shafts and bearings for these engines to.
The oil pump is, I recall, also running at higher than crankshaft speed (possibly x2) and has to pump unfiltered oil, so even though it has a relatively light duty it is subject to potentially even greater wear and tear than the TC and crankshaft bearings.

One of the interesting points is that the engine Makers oil pump is usually expensive to renew and is often left in service too long, sometimes reaching critically low oil pressures. We all know how a worn oil pump can compromise the oil's ability in keeping the metal parts from coming into contact.

There are, however, effective cheaper options to avoid a lot of these problems(see my previous posting refering to the Oilmax Systems 6Bar pump and centrifuge) .

The MaK M20 (if you have any of these) usually rely on 20μ full flow filtration, whereas the centrifuge typically achieves <1μ particle separation.  The centrifuge also achieves REMOVAL of soot, not retention of soot like the filter.  Both are of course essential if you want to keep your engine operating at acceptable wear rates and TBOs.

As Engineers we are, after all, in the business of protecting the machines we are managing for our Owners.

I hope you find this helpful

Best Regards  David Stevenson