Advice from engine guys, please.
Discussion
What is the likelihood of an engine that has been run extremely low on oil, and presenting with a bottom end knock, being partially rescued by just fitting new bearings, and not changing/regrinding c/shaft?
For completeness, BMW F20 116i. Low oil light did not, at any stage, illuminate.
When level was checked via interior control, it showed as full.
Car was bought from non-BMW source, and was serviced before collection, approx 9k miles ago. Currently with 48k miles.
For completeness, BMW F20 116i. Low oil light did not, at any stage, illuminate.
When level was checked via interior control, it showed as full.
Car was bought from non-BMW source, and was serviced before collection, approx 9k miles ago. Currently with 48k miles.
More doom and gloom from me I'm afraid. I can't remember having a crankshaft re ground in the last 20 or so years to repair bearing failure. If it's knocking it's probably already worn beyond the available oversize bearings. I would also be concerned at the condition of the camshaft and associated bearings and/or cylinder head.
Once again though, as above you won't know until you have a look.
Once again though, as above you won't know until you have a look.
Although I've done the vast majority (99%) of maintenance work on my cars/bike for the last 40 years, the last crank that I had in my hands was from a 250 2 stroke twin, in, I would guess, '81/'82!
I'm not sure how much visual scoring I'd looking for. Colouring? Would I need to resort to Plastigauge?
TIA.
I'm not sure how much visual scoring I'd looking for. Colouring? Would I need to resort to Plastigauge?
TIA.
stevieturbo said:
Thousands of cranks are reground and fixed every week. It'd need to be one hell of a knock or special crank for it to be un-usable.
You're right stevieturbo but the biggest issue nowadays is that on a lot of engines bearings aren't available beyond 0.25mm.In my experience if it's knocking, the wear is already more than that. I am prepared to admit I could be wrong though-just don't tell the wife I said that!
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