[jeepers creepers]

While tearing down oil pump today i've took off some cap to see main bearings conditions and this is what i've found:
[IMG=http://img141.imageshack.us/img141/4468/img0476d.jpg][/IMG]

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engine had run for about 2 h, just for the set up, non road, i've cleaned doing my best all tunnels, holes everithing in the engine blowing with compressed air, and solvent, engine was perfect at the assembly, coated all bearings with specific lube, checked all the clearances , they were fine...
As you can see crank looks like perfect, but wear pattern on the bearings are telling something wrong, misalignement?
i'm so frustrated.

[oldbogie]

Originally Posted by jeepers creepers

While tearing down oil pump today i've took off some cap to see main bearings conditions and this is what i've found:
[IMG=http://img141.imageshack.us/img141/4468/img0476d.jpg][/IMG]

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engine had run for about 2 h, just for the set up, non road, i've cleaned doing my best all tunnels, holes everithing in the engine blowing with compressed air, and solvent, engine was perfect at the assembly, coated all bearings with specific lube, checked all the clearances , they were fine...
As you can see crank looks like perfect, but wear pattern on the bearings are telling something wrong, misalignement?
i'm so frustrated.

Looks like a lot of very fine material circulated with the oil, I'd guess stone remains left on and in the cylinder walls from the honing operations.

Keep in mind that bearing shells don't fit perfectly round, there are high and low spots a few millionths of an inch in difference. You will see the high spots as shinny areas on the bearing. It doesn't take much more than a piece of lint under the shell to cause this.

Bogie

[jeepers creepers]

Thank you for the quick and professional response as usual Bogie.
Can the "fine material" be the Moly grease used on the bolts?
i've seen a lot of this in the oil pan, i did an oil change already but the fine particles are probably heavy so they tend to stay.
i'm afraid to see rod bearings now, don't know what to do, i've a new set of bearings on the shelf but i think that once changed the story will start again so it's probably useless.
Any advice?
Thank you.

[cobalt327]

The image that didn't show:



Looks wiped like from a momentary loss of oil pressure or from low pressure at start up. I would start by cleaning the caps, the block registers, bearing inserts and crankshaft. Then I would either mike them or at least use plastigage to see what the clearances look like.

Were the main saddles checked for round, or honed?

Carefully cut open the filter to see what it has picked up- this will likely show you what caused the grooving seen on some of the bearings.

Get a look at the back of the bearings to see if there looks to be anything caught between the bearing and cap or block.

[BOBCRMAN@aol.com]

You did all that prep to the block. Did you clean the crank, clean the oil passages with pipe cleaner, wash with detergent and blow dry.

Grit damage like this is usually caused by a dirty crank. I see it quite often from customers that ASSUME the crank is clean..Thats why standard/re-grind cranks come with a written disclaimer.

[cobalt327]

What Bob just pointed out makes me also wonder if the crank oil passages were cleaned out after the crank was turned, because the crank can look clean, yet not be. The shop shouldn't be held to cleaning it completely after machining- unless they're paid to do so (time is money after all).

[jeepers creepers]

thank you guys,
well i'm feeling guilty but i remember to have cleaned the crank pretty good, brush, solvent and compressed air several times but after all as you says it can be dirty anyway.
Block has been bored and honed, here in Italy is hard to find a decent machine shop and as "decent" i mean just to do their work and make sure all the tolerances are ok.
They probably haven't the tool to bore the maincaps and mine sure wasn't, block was in very good conditions, that's for sure but probably maincaps bores now are not perfectly round and this cause this kind of wear.
As i've said before, there's a complete bearing kit on the shelf i've brought for another engine so i can change them but my concern is to get them quicky at the same point as before.
Engine is already on so work on it is not so suitable and even the basic measurements could be difficult now.
How long bearings will last in this conditions in your opinion?

[johnsongrass1]

Clevitte's website has a bearing failure guide that quite useful. Those bearing look OK enough to me. Mostly they look like the main bores aren't round. Most blocks aren't round and need at least a little attention.

[cobalt327]

Originally Posted by jeepers creepers

How long bearings will last in this conditions in your opinion?

Were the cap bolts replaced w/studs? What do the rod bearings look like? This is important because if the rod bearings look normal, the possibility of the main bore being out of spec greatly increases, IMO.

Any chance you can have the main bores measured w/a dial bore gauge- or even carefully used snap gauge and a micrometer?

Was this the engine that had the mysterious oil pressure gauge fluctuation?

If the crank oil clearances, taper, out of round and straightness all fall within specs (taper and straightness seem to look OK), and the oil pressure is adaquate, AND the saddles are OK, the engine could have a normal life expectancy. But the cause for the wear should be determined. I would concentrate on the oil clearance, the out of round of both the crank main journals and the main bore.

I'd be less concerned w/the wear caused by grit than the apparent wiping that has happened. But obviously if the bearing wear were to continue at the rate it is now- w/2 hours of non loaded run time- there's the possibility it may not last long at all.

[jeepers creepers]

i didn't see the rod bearings yet, i hope they'll be better than these, main caps got new ARP bolts but not studs, yes, this is the engine with the mysterious oil pressure fluctuation we spoke about in the other thread," M55 oil pump done after 5000 rpm".

[johnsongrass1]

The studs will pull the caps a little outa round for two main reasons. The first being the torque values change slightly as the threads on the stud are little better then then the stock bolt. The better fastener usually gets a little more load even though the torque value may be the same. The second, the stud will pull the block slightly different than a bolt. Sometimes its enough you can get away with it and sometimes it's not. It always best to error on the side of caution.

You need to get the pump issue fixed. It doesn't look like you have hurt the bearings with lack of oil yet but it's never good.

Is your block had the main bored or honed? Was the crank installed new or was it checked for round journals?

[4 Jaw Chuck]

Looks 100% normal to me...no issues...what you are seeing is normal run in wear. Run it as is, that thin coating gets scuffed as soon as the engine is started and any number of small particles can cause the minor scuffing you are seeing. As long as your not seeing copper backing plating your good to go.

Here's a sample of what it will look like after 150 000 miles with regular oil changes.

[jeepers creepers]

thank you so much for all the infos and picture as well.

I've brazed the pick up at the oil pump cover ( that was a bit low...) and mounted the maincaps with the old bearings, so now we'll see what will happen down the road.

[cliff tate]

Iagree wiyh 4jaw,bearing shells have a thin lead tin overlay to acomedate some imperfectionand debree.fines ar imposible for the average builder to completly eliminat.you ar fine inst. new filter and oil and use it cliff

[mouse77]

There is nothing to worry about there. The bearing has a micro coat of the grey color you see for break-in. That coating is not presicion applied, more of a spray on/dip deal, and it will have high and low spots that the actual machined bearing surface does not, hence the odd pattern you see.
And the scuff's you think you see are actually the machined surface of the bearing, not a wear issue.
Take a brand new bearing out of the box, and LIGHTLY with fine scotch bright, gently scuff the grey coating and you will see a shiny bearing surface under there.