• Engine rebuild question

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by Allen Hazen
I am ignorant.

First, a couple of things I ***think*** are true: please somebody set me right if they're not!
(1) To replace the crankshaft (in an EMD diesel engine), you'd have to separate the crank-case from the oil pan (so: major work, needing a crane that can hoist several tons of metal).
(2) The crankshaft is probably about the most expensive single-piece metal component in the engine. (Well, maybe the whole crank-case structure is more expensive, but of the thi8ngs you install IN it....)

Next, a general question:
How common is crankshaft replacement? As in, suppose a railroad buys a hundred EMD locomotives and keeps them for thirty years: how many crankshafts would it expect to replace in them in that time?

Leading to the question that inspired all this:
The "launch" version of the 8-567C (and also the launch version of the 12-710...) had vibration... issues... that led to the introduction a few years later of the 8-567CR with revised cylinder firing sequence. In principle I'd think you could rebuild an 8-567C into an 8-567CR (so your early-production SW-900 would run more smoothly...), but it would involve replacing the crankshaft (and the camshafts, but they should be cheaper). Does anyone here know if this was actually done, or did purchasers of the early version just live with the problem?
  by mxdata
Allen. your observation is correct, to change the crankshaft on an EMD you have to remove the gear trains and their housings, and separate the crankcase from the oil pan. But if you did a good job of maintaining your engines, changed your filters on time, monitored the oil condition, and did not get into any oil contamination problems, the chances are pretty good that the engines would run from overhaul to overhaul without needing any unexpected crankshaft replacements.

The "CR" engine replaced its "C" predecessor in production, and was a direct field replacement as a complete engine, but the modification package was not usually fitted to earlier engines because there were differences in other engine parts to accomodate the larger and heavier crankshaft and camshaft counterweights.

  by RickRackstop
The most common cause of crankshaft damage is from contaminated oil as from fuel oil dilution and from water that corrodes the bearing surface. Then there is the subject of loss of oil pressure due to pump failure. Then its litigation time as in why didn't the safety system shut the engine down and so forth. There are engines out there with over 45 years of service and pushing 3000,000 hours with the original crank.

I found this site fascinating with some of the stuff they can repair on site and this company is by no means the only one, just the only one that publishes pictures. http://www.emdservice.com/Default.asp?PAGE_ID=4
  by Allen Hazen
Thanks, Mxdata and Rick Rackstop!
I didn't know about the heavier counterweights. I ***think*** (it's been a while since I read this, and I'm not sure where the relevant copy of the Australian railfan magazine "Motive Power" is after my move to a new continent) that the New South Wales 82-class (twin-cab CC hood units) were built with the original version of the 12-710 and that, although a new version with different firing sequence had been introduced since their construction there were no plans to modify them because of the expense involved.

Next question: just what was Chrome Crankshaft's business? I had the impression that they plated (?) worn crankshafts to restore them to original dimensions. Would one expect a unit that had been working for 45 years and pushing 3,000,000 hours to have had its crankshaft out and "refinished" one or more times in that period? Or have I totally misconstrued something I read with less than full understanding long ago?
  by RickRackstop
EMD allowed crankshaft journals to be resized by chrome plating up to 1/8 inch. Marine crankshafts, however, are ABS ( American Bureau of Shipping) inspected and they don't allow it. Marine crankshafts will have a Maltese cross stamped into them next to the serial number. The damaged marine crankshaft is worth a lot more than scrap value.
Ellwood Crankshaft Group seems to have come out of nowhere and they will do major repairs on crankshaft including building up worn or damaged surfaces.
  by Allen Hazen
Rick-- Thanks again! Your answers... keep piquing my curiosity: I fear I could go on thinking up new questions far longer than you would want to answer them!

Somehow the idea that ABS imposes rules on engine crankshafts that don't apply elsewhere doesn't come as a COMPLETE surprise. I have the impression (from discussions on naval-history sites a long time ago) that at least some of the differences in construction between merchant ships and naval vessels are due, not directly to judgements about what is necessary for safety, but to standards without which insurance (etc) is unobtainable.
  by RickRackstop
ABS is a classification society and owners have to satisfy it for insurance purposes. Marine engines have to have a different manifold for instance where the legs are divided and each cylinder has a thermocouple to measure exhaust temperature. There are also a spring loaded injector link where if one injector hangs up you still have control of the engine. They require that the engine be able to keep running at all sorts of angles as in a seaway hence the deep oil pan. The Norwegan Societey required a test for drill rig units to operate at 45 degrees, i.e. while in sinking condition so that there would be power while everybody got off. That required dry sump lubrication. I think they thought better of it.

Getting back to railroads, in this country there is FRA regulations and now EPA also. In Europe the Class 66 locomotive has been approved for cross border operations in several northern countries besides the UK. So every country had a hit too.