Low compression / weak cylinder

[4wheelfurry]

...
Only a couple or more questions: How did you get the piston so clean? And what bent the push rod? Is there any wear step in the cylinder at the top of the ring travel? And do you plan to do a light hone or no?

rScotty

The piston is exactly as it was removed I didn't clean it in any way. Actually the whole engine is this clean I really didn't even get that dreaded diesel oil stained in my hands lol. Guess low hours and good maint is to thank..
As for the push rod it isn't bent the lower end is a male "ball" socket but the top is a female "bell" socket. That bell had come un-pressed from the push rod tube and it separated but it couldn't come apart because it was held squished together... Ever since new I heard a faint noise in the valvetrain but it always ran fine. So when I pulled the rocker rail one of my push rods fell apart and then I know what the sound was lol.
And zero ring grove not even any carbon build up at the top, the piston pushed right out.
Over the years I've built hundreds of small engines mainly ATV and motorcycle engines. Along with quite a few autos but very few diesels I'm just not a fan of diesel grease lol. Anyway I have learned if the cylinder looks good its best not hone it just leave it be. I well understand honing is a hot debated topic and I understand the purpose of what honing does but it also removes material and IMO the oil ring is designed to wipe the oil off anyway. The only time honing is needed is after a bore to rid the screw process of the bore machine but in a perfect world a smooth cylinder is best for a oil ring to work... And I don't buy the wear pattern idea that new rings won't seal because the old rings had a wear pattern relationship with the cylinder I've built enough engines (not honing) to know this isn't true.

 

[HarryVanderpool]

Interested in how the story ends.

 

[rScotty]

Interested in how the story ends.

Me too. It sounds like 4wheel knows his mechanicals. Mine don't ever seem to be as clean as his is. I agree; much nicer to work on a gasser or propane engine.

That push rod construction with the bell and ball swaged into a tube is a popular way to manufacture a push rod. I've seen them with loose ends myself, and wonder how common it is. I doubt that it could cause a problem, but could definitely be the source of some confusing valve train noise. I once took apart a British MC engine in which ALL of the push rod ends were so loose I wondered if it was deliberate.

On cylinders and rings, I've honed and not honed and slightly honed... Frankly I've never been able to determine if honing makes any difference. I don't believe I've ever had a set of rings "not seat" in a rebuild where the piston-to-cylinder clearance was reasonable.

In fact, I'm always surprised at how much you can "get away with" in a repair and still come out with a good running and long lasting repair.
rScotty