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Topic Review (Newest First)
03-06-2011 09:06 AM
cliff tate
bearing wear

mouse is bang on if you ar building a engine to run nascar or a non claimer and hope to get all season out of 1. but i don't think to maney on this site are in that Erena. I worked for a cat dealer,we did a lot of engine work, 1 year we built 52 3208 cat truck and ind. engines.each one was assembled and clearance checked with plastigauge. not 1 failure.tho every engine was pre lubed then dynowed, 5min warm up full power for 30 min cool down 10 then to the customer.the moral hear is cleanliness senceable checks on assembly.we did find issues with plastigauge and send parts back to machine shop. clif
03-05-2011 10:45 PM
Torque454 I think i'd stick it back together and run it. I've run engines with worse bearings than that with no problems. It may not be ideal but it works.

I think almost every used engine i've been into has had imperfectly worn bearings. Even quite a few with copper showing. Some are still running and driving. They aren't high performance engines or anything, and wouldn't be much of a loss if they did spin a bearing or something so i've just run them. Those bearings you show look pretty good to me compared to most bearings I see. May not be perfect, but I dont think any bearing will be perfect for very long anyways.
03-05-2011 08:17 PM
mouse77
Quote:
Originally Posted by Dougie
Question,

If the bearings have a spray on coating that isn't precision applied, wouldn't that cause inaccurate readings when checking the size using either a micrometer or plastigage?
Yes..... thats why competition bearings have no coating. As for plastiguage, youre mashing plastercene and measuring it, by eye, off of a printed stripe on paper. Great for a rough idea, but not very precision. It also doesnt tell you if your bearing crush is off and the parting lines are wide or if the mains have been ovaled.
"most" engine builders, besides for the armchair engineers here, lightly (with grey, "very fine") scotchbrite the coating off before using a bore gauge to determine clearance when using cheapie bearings. Its a startup coating and if you use any assembley lube it really isnt needed.

And the funny part is, unless you have 10 sets of + and - .001 and std fit bearings to match the under/oversize bore to bore and a crank polisher on hand, measuring anything besides the basic .010 etc, wont do much other than allow you to tell someone your clearance on a web forum.

YES, this fellow may had have a little trash in the crank oil holes he missed, or maybe the cam bearings were left in before hot tanking and some gunk was in the grooves, or maybe driving in the new cam bearings knocked some casting sand out of a crevice, but like most people said, he has nothing to worry about.

And im going to go out on a sturdy limb and say that "damage" was caused either by rolling it over by hand, or an extended cranking time, no fuel, dead battery etc.
Because as im sure everyone knows on here , the crank doesnt actually ride on the bearing when it has oil pressure, it rides on the oil "sheer" created by the oil pressure in combination with the clearances. Your crank actually floats in the mains on oil. Pretty cool huh?
So there is no bearing to surface contact, unless the engine doesnt have a live oil supply.
03-02-2011 12:39 PM
Dougie Question,

If the bearings have a spray on coating that isn't precision applied, wouldn't that cause inaccurate readings when checking the size using either a micrometer or plastigage?
03-02-2011 10:49 AM
cobalt327 #1 looks OK. #5 doesn't look bad. That there's such a difference between the bearing on the left and the others points to an irregularity that I would be looking into. Might have been nothing more than an oil passage loaded up w/grit to that bearing- but I won't call it "normal". YMMV.

03-02-2011 01:18 AM
4 Jaw Chuck Its not through the coating/plating, if you can't catch a fingernail its a "lint/dust" scuff....looks pretty minor from my chair.
03-01-2011 10:30 PM
cobalt327 This is not caused by the 'coating' on the bearings.
03-01-2011 10:04 PM
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.
03-01-2011 11:51 AM
cliff tate
marks on bearings

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
03-01-2011 10:50 AM
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.
02-25-2011 12:50 AM
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.

02-24-2011 08:23 PM
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?
02-24-2011 04:21 PM
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".
02-24-2011 04:15 PM
cobalt327
Quote:
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.
02-24-2011 03:49 PM
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.
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