Cummins Engine—Rebuild Or Replace?

Initially we were firmly in the rebuild camp, as were most of the experts we consulted. After all, at 6000 hours our engine is, in the words of David in his comment, “[a] baby and has many hours running [still] available”. Rebuilding would also save all the expense and aggravation of changing all kinds of things on the boat to make a  new engine fit. Not trivial in that the expense of such changes can run to half, or even match, the cost of a new engine.

As long as the repair looked like a valve job and maybe new piston rings, the price, while not trivial, was palatable at about $7000. An estimate based on doing it in Morgan’s Cloud’s spacious engine room without the expense of removal and reinstallation. Better still the boat was stored at Billings Diesel and Marine, one of the best in the business of engine rebuilds.

Bad News

But then we found that the cylinders were out of round and would require re-boring, necessitating removing the engine from the boat, complete disassembly, oversized pistons, and on it went. The price jumped to $11,000 and maybe as much as $13,000 if things did not go well.


In the end we decided to go with a new engine for the following reasons:

  1. The new engine at $14,500 was only going to be a little more expensive than rebuilding the old one.
  2. The new engine comes with a two year full warranty. While I’m sure Billings would stand behind their re-build, if anything new went wrong with the engine we could be out the re-build and still have to buy a new engine. A particularly worrying thought when dealing with an engine that has, in our opinion, had not one, but two manufacturing defects. (When the engine was brand new we found several oil pan bolts stripped. Cummins fixed this on warranty.)
  3. While trying to fix this engine, 3 out of 6 new or remanufactured injectors that we bought from Cummins  had to be rebuilt by a local fuel injection shop before they functioned. Therefore we were concerned that the parts we would need to use in a rebuild might be defective too.
  4. Cummins no longer makes this model of engine and parts are already becoming more difficult to get on a timely basis.
  5. We think we can improve our fuel economy with the new engine. (More on that in a future post.)

Do you think we made the right or wrong call? Leave a comment.


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