biscuitville

Tearing apart my engine after finding some filings on the magnetic drain plug. I have found some of the bearings indicate metal has been pressed into them and there are some gouges. The crank seems to be okay - may need to be polished up. Just got started looking at the rod bearings and will finish that this weekend.

The wear showing on the crank bearing in the pic below (at the ends towards where the bolts are) was seen on every bearing, front to rear.
Does this wear pattern indicate I need a line-bore or line hone?

biscuitville

Here is the pic (trouble using the insert image function while in IE 9, works ok in FF).

7t9l82

they aren't exactly what i would call pristine. it looks like some debris was floating around. have your crank checked and see if it can just be polished. does your fingernail grab onto anything on the cranks journal?

CanadaGrant

With lines like that in the bearing, especially the one about a third of the way out from the left side, there is no way your crank will not need to be turned. You might have to only go ten thou but that isn't going to be a polish job. Grinding a crank is not really all that expensive so don't cheap out since you already have it apart.

cardo0

Totally forget the line hone/bore. Nothing to due with bearing surfaces. All the crank has to do when reinstalled is turn freely by hand. U can get bearings a tiny bit oversized to if needed to bring back into spec. Unless u bent the crank is should be good to go with a polish or cut 0.010" under or more. Aline honing/boring is for new/replacement cranks or bent cranks that dont line up when assembled. Yours shouldnt have changed. BTW aline hone/boring increases the distance between the crank and cam which loosens a stock length timing chain which in turn makes the distributor timing (phasing) sloppy - yes reduces power if not corrected.

The real problem is that metal circulated inside the engine and its oil galleys. Only way i know to get it out is hot tank and clean the block. And where did the metal come from? More than likely the cam and the cam & lifters are/were wiped.

Sorry for the bad news.

augiedoggy

Mine looked like that in the short block I bought prior to teardown because the po broke a ring and had that fixed but apparently left the debris in the oil and block. I found all sorts of trash it the oil including an electrical spade connector.
I replaced all the bearings as well as the crank. It had some bad grooves.
Ironically the cylinder walls looked fresh and the pistons and rings were new as I was told with less than 7k on them.

biscuitville

I didn't think to mention it in my original post - this is not the original crank for this block. The forged crank has been ground before and so I need to measure it and see if it could be ground further w/o any problems. On one of the crank journals, I can feel something with my fingernail.

The lifters are in great shape though. Going to look at the cam tomorrow.

Question about the chain lengthening comment - isn't the amount taken off the crank made up for by larger bearings? Wouldn't that leave the crank to cam distance the same, or am I thinking about it incorrectly? Why would the distance between the crank and cam increase? Did you mean to say decrease so the chain would loosen?

cardo0

Hey good catch, i didnt even notice that mistake. Yes align honing/boring would decrease the distance between cam and crank. That makes for the looser timing chain - though there are tighter chains available most machine shops dont even know how to measure and correct for this.

Ok ill try to explain the align hone/bore resizing. Most auto machine shops that have the correct machine for this want to use and charge everyone they can to make it pay for itself saying it is necessary. Not so if u read the chevy power manual or most overhaul books. For stock street installs with the crank returning to the same block all it needs to do is turn freely by hand after install w/new brgs. When the crank saddles in the block are honed even a little this takes metal from the block and moves the crank that much more up into the block. The metal on the cap is corrected by machining down the cap to make a perfect round hole for the crank to fit in. The same thing occurs with the rods. When the "big end" is reconditioned the crank journal end is enlarged by honing and then reduced by shaving/machining down the cap to exact stock size again. JFYI most machine shops also add a tiny angle to the rock cap to help the "crush" on the bearing.
No change in bearings size is needed unless the crank has been turned then it needs "undersized" bearings to match. When u hear the crank turned 10/20 it means the crank has been cut 0.010" on the crank and 0.020" on the rod journals.

Now that u provided some important info in your case u may need to have an align hone/bore for the replacement crank - maybe not. I would hold off on the block align hone until u fit up the new crank. But everything ive read tells me u can grind a crank as long as u can find brgs for it so not to worry for turning down the crank - it actually a performance trick with some high rpm motors to turn the cranks way down to reduce friction.

BTW withholding information just wastes both your time and our time trying to help u.

If all this was easy women and children would do it.

biscuitville

Thanks for the explanation.