OM 603 engine. Need help identifying the markings / colors to order the right crankshaft bearings. Thank you.

I'm not clear on your request. I just did the mains in my OM617 and I just mic'd the crank and ordered appropriate bearings - in my case, stock 70mm. This was a good thing as that's all Pelican offered though I'm sure there are others available.

I did need a 2-3" mic as I didn't trust my calipers for a precise measurement like this. After searching around I found a set of 0-1, 1-2, and 2-3 at Harbor Freight for $39 - a real steal. They seemed to measure right on as far as I can tell and had a 1" and 2" standard included which the $134 Starrett did not (though I'd love to have Starrett if I could afford it).

Dan

if your crankshaft is in good condition and not needing and polishing or grinding all the cranks came with standard bearings from the factory, meaning your engine has never been rebuilt, it would have 70mm bearings standard. I would still plasti gauge them when installing them 3 thousands clearance is what is needed to allow for proper oiling. good luck.

Yes those crank color markingsare for slight tolerences, but as already stated standard bearings are ok,

I tried to order standard bearings, but the dealer asked me which color I needed. If I follow the image, I end up with 3 different colors. I am not sure this is specific to my engine though.

You've posted a picture of the block in your original post.

In the screen shot of the FSM you've provided in post #5 it says you need to look at the crankshaft for the bearing caps there's meant to be identifying information there.

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Don't leave that there - I'll take it to bits!

I'm thinking you're overthinking this. Of course we all want a good foundation for our engine builds but as long as the oil clearance is in spec you're good to go.

Mic the crank (or you can have a machine shop do this for you for little money if you're unsure of your skills in this area) and do a little math. You may have to convert the shop's measurements to mm if you're in the US but there are several good online conversion programs that will do this for you. The 70mm bearing shells are 70mm INSTALLED ID so you can simply subtract the measured crank dimension from 70mm and get your actual oil clearance. It just needs to be in spec. Also ask the shop to check for roundness and taper - if it's a good shop they will do this automatically. There are specs for this and again as long as the crank is in tolerance you're good.

No way would I pay dealer prices for bearings. The ones from Pelican are German made and are excellent quality. I paid about $65 for mine.

EDIT: I hope you marked the main caps or kept them in order somehow. They are NOT interchangeable as they're machined in place when the block is align bored in the factory. If you get them mixed up the block will need an align bore (sometimes called "line boring") to get them back in line. I noticed in your pic that the caps are off.

Dan

I'm far from an expert, but in my other experiences with German engines, it looks like you need a red for the rear and a yellow for the other one. That being said, Germans are super anal about this stuff, but on a rebuilt engine, I don't think the colors are relevant anymore. You need to get the correct bearing to obtain the clearance within the specified tolerance. Does that mean buyiing one of each and measuring to see which fits the best? I hope not! But you might start with the $65 peachparts bearing, measure it and go from there. If its too loose, then you can get creative with colors.

With a worn / used crank, the markings may no longer be valid. Get the crank crack checked / polished and miked at a machine shop. You will spend ~ $ 40

With this data you can select the proper bearing. Factory selected bearings are all " standard ", they just vary a slight bit to compensate for crankshaft size variances.

If you have the crank reground, you selection is limited to specific undersizes.

Blue marking is smallest, yellow next size, red is the largest. in 58mm inside dia=2.255-2.260= use blue, 2.260-2.265= use yellow, 2.265-2.270 = use red --- in a standard size those 3 will work, these are for a 350sdl, but i believe the six cylinders all use the same sizes- for oversize different colors are used 57.75 use blue 2.375-2.380,57.75 gelb 2.380-2.385, replacement oversizes up to 4 are ,were also available, this is wis info as im building a c36 from scratch, using a 3.5 diesel crank in a 104 case i was researching what bearings i would need if available, hope this helps , i woukld let machine shop give you measurements and fit and measure, or with plastigage works good, to make this clear original = use blue/yellow or red , 1st oversize use blue or gelb? (GERMAN? GELB) 2nd oversize use blue or yellow or for 2nd,3rdm4th oversizes