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Discussion Starter · #1 · (Edited)
I just pulled the pistons out of my "S" engine to do a rebuild, and found some surprising and alarming issues. First thing I found was an oil-control ring had escaped it's grove, ring was bottom-most of the 3-part OC ring, #4 piston. The ring has dug a groove into the liner that is easy to feel, so I suspect I need a replacement, if anyone has a single spare before I cannibalize one of my other engines. The ring does not show any indication of being pinched when it was assembled, is it possible for it to have escaped the groove while running? ring does not show much wear, and was new when I re-assembled the engine, liners still show cross-hatching
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Second issue was a deep groove in the #1 journal. The groove is quite deep, but curiously the bearing shows no evidence of the gouge, and this engine was running. I had uneven compression, and pulled the engine some time ago, can't recall the specifics. I can replace the crank with one from a standard 164 engine I have, are they identical to the crank from an "S"? how is it possible an engine can run for a few months (at least) and the bearing not show evidence of the groove in the crank. I can't think of any other possibility other than I missed it when I re-assembled the engine last time, and the damage was already present, perhaps smoothed and a new bearing installed by PO. No idea of the car's history, other than I bought it with bent-valves from a close encounter with the piston crowns from a slipped TB.
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Hi
The grove in the #1 rod journal is a normal, machined there by the factory, part of the crankshaft. You're not the first person to be surprised by it and not to have seen it on initial assembly. Search this board and you can find several threads about this feature.

The function of the grove is to provide an additional oil supply reservoir for the #1 rod bearing. Oil supply to the #1 rod bearing is not as good as the rest of the rod bearings so the groove makes up for that by providing a back up oil reservoir.

All 164 crankshafts, indeed all 3.0L crankshafts are the same. The only exception is the crankshafts in later 24V engines (never sold in the USA) that don't have an auxiliary shaft. Those crankshafts have a machined down area where the chain driven oil pump drive goes.

Hope this helps
 

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Discussion Starter · #3 ·
Thanks! not sure whether to be relieved that it's normal, or embarassed that I didn't see it before.
 

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Thanks! not sure whether to be relieved that it's normal, or embarassed that I didn't see it before.
Hi Stan
No reason you can't do both !

At least from the picture of that lower connecting rod cap, there's quite a bit of debris on the bearing surface. When you rebuild the engine really get it clean. Take apart the oil pump blow it out with compressed air, clean the pressure relief valve & spring.

In regard to the oil ring, that's pretty mysterious. I'd contact the oil ring company see what they think, hopefully they will let you mail it to them for analysis.

If the #4 3.0 liner is no good, I'm interested in it.

Hope this helps
 
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