130TC crankshaft blued journals...

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Abarthnorway - Remi L
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130TC crankshaft blued journals...

Post by Abarthnorway - Remi L » May 10th, 2019, 11:56 pm

Dismantled a 130TC many years ago due to rust and two nonexisting exhaust camshaft lobes. The engine had done approx 240.000km. I noticed a bit of wear on bearings...bronce coloured spots, and pretty sharp bluish shine journals on all journals. I have never seen this before, so I polished the crank out of curiosity to see what happened.....
The blue «layer» disappeared quickly - and I could find no scoring whatsoever. A bit surprised I measured the crank with micrometer, and found it to be round and within specified tolerances.

I still have this crank stashed away, but have not dared to use it, as I am not sure if it might have had some kind of damage done to the hardening or other...

I have two questions:
- What happened?
- Blue journals = scrap crank?

(Never took any pics, but ripped one from the web. I had bluing on all journals - just like the thrust area on the picture)
8D1866DA-9E9C-4910-B134-9801E898FCF4.jpeg
8D1866DA-9E9C-4910-B134-9801E898FCF4.jpeg (58.91 KiB) Viewed 122 times
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Guy Croft
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Re: 130TC crankshaft blued journals...

Post by Guy Croft » May 11th, 2019, 10:27 am

'blueing' is discoloration of the crank material due to overheating. It can usually just be polished off...

However overheating like that can bend the crank - so a runout check on the center main journal is vital...


G
Guy Croft, owner

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