Attention Diesel Gurus

[HoffaLives]

I decided to pull the head on my Westerbeke 30 aka Leyland 154 tractor engine because of a head gasket leak. Upon doing so I discovered to my surprise that there is absolutely no bore ridge at the top of the cylinder. The upper piston ring stops about 1 cm. down, and yet after you scrape away the carbon, you cannot tell the end of travel the bore is so smooth.

This engine is 27 years young and I was thinking about rebuilding it soon (it runs fine) but seeing such little bore wear, I'm wondering if it's necessary. Hours are unknown but likely over 2,000. Are diesels different than gas engines in this regard? Every gas engine I've worked on that needed a rebuild always showed some bore wear.

I know this is only one factor to consider, but I would think that it would be a marker for overall engine wear.

[Tartan34C]

It is an indication of wear. If the oil was changed regularly and you don’t have any problems don’t try fixing what isn’t broken. A marine diesel will run a lot of hours and keeping it clean (heat exchanger included), dry, rust free and running on fresh oil will extend its life quite a bit. Don’t let it idle too much and don’t push it too much.
All the best,
Robert Gainer

[sailaway21]

Who says the sun doesn't shine on every dog's butt sometimes? New head bolts, new gasket, and it's Miller time. I'd say your conclusions are correct.

[USCGRET1990]

I was on a 95 footer in Ak back in 1978-80. We had two generators (diesel)
that each had around 25,000 hours on them and still going strong. That is not a typo.

[soul searcher]

I agree with Mr Gainer and SA don't look a gift horse in the mouth. I'll bet you can still see the honing marks in the cylinder bore. change the gasket and get new bolts and do the happy dance.

[jrd22]

It is fairly common for the liners to not show much wear, especially if you only have 2000 hours on it. You could still have worn rings which would result in low compression and increased oil consumption, but if it starts well and isn't using oil I'd say you are good to go(for another 27 years?). John

[Faster]

I'd agree with JRD, we experienced this problem - the bore was fine but the rings had actually worn to the point that there was a 1/8" gap between the ends, and eventually the compression got so low the engine wouldn't start.

But if you've not been having difficulty starting this engine, then perhaps your are, indeed, good to go for a while yet.

[Rockter]

Hoffa...

That's good news on the bore wear. I wonder would a new set of rings do the job? Typically they are not too expensive, and lifting the barrel is not much more work.

You could check the ring-end gaps, as suggested. Perhaps they are OK too, in which case just re-assemble the old motor.

[USCGRET1990]

It's best not to put new rings in an old bore or disturb (rotate) the old ones
unless you plan on a total rebore with new rings. There is a wear pattern established and best if maintained. It would be worth installing new gaskets, run it until warmed up then do a compression test.