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Old Thu, Aug-30-2018, 08:42:33 PM   #1
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Default S65 Crankshaft Blue coloring. Need advice from experts

2008 E92 M3 DCT 85k

Going with BE bearing and ARP Bolts.

I got a call from the shop they noticed Blue Coloring on CrankShaft.

Possible main bearing issue they said.
I dont completely agree, because there is no evidence blue coloring started from near/around bearings/journals. Because heat mark (blue Marks) are not coming from the middle, rather they just show up at the ends of counter balancers.

I'd like to know if anyone knows why its blue ? Possible from hardening process at manufacturing ? if so why isn't the complete crank same color rather than only near rear end of the engine ?
And what could have cause it to turn blue ? bearings do not look toasted at all, they have same wear everyone has experienced, maybe little more chip than even wear.

Here are some photos .

I went for a visit I took videos and pictures. They had 2 sets of bearings off already .

If anyone has time to look through these and let me know what they think, that would greatly be appreciated.

Thanks in advance.
Attached Images
File Type: jpg IMG_9529.jpg (128.4 KB, 61 views)
File Type: jpg IMG_9534.jpg (108.1 KB, 54 views)
File Type: jpg IMG_9527.jpg (77.4 KB, 44 views)
File Type: jpg IMG_9526.jpg (108.4 KB, 59 views)
File Type: jpg IMG_9538.jpg (100.3 KB, 46 views)

Last edited by gmann; Fri, Aug-31-2018 at 12:20:14 AM.
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