I have heard people who say they have dropped the oil pan and pulled the crank caps of and bearings and then emery paper the offending areas.

Anyone ever seen or done this themselves and if so just how well did or didn’t it work?


Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

quote Originally posted by 84fiero123: ... if so just how well did or didn’t it work?

I have never seen it but I am a ruffneck. It is a band aid solution. It would work, with new bearings, for a while. A crankshaft is machined to tolerances. You can't do that by hand with emery paper. More than likely, you will throw off trueness by rubbing on the offended area. Why didn't the softer brass bearings absorb the damage ?
That said, emery paper may not help but it can't hurt. Another saying comes to mind. If you don't have time to do it right the first time, you don't have time to do it again.

quote Originally posted by cliffw: Thinking about it, when they machine a crank over sized bearings are used. Will undersized bearing(s) work ? What kind of damage are we trying to repair ?

I wouldn't think undersized wouldn't work if you use emery cloth to try to clean it up and get it back into round. You would be taking material off the journal so you would need oversized bearings. I think it might be doable, but as you said it's more a bandaid as it would be real difficult to get it back into round without machineing. It would really depend on how messed up the crank is to start with. If it's to out of round, I wouldn't attempt it. If it's just some surface scouring but still round, then maybe.

[This message has been edited by Khw (edited 01-21-2013).]

I've done it on small engines with good results.
If it isn't on a race car, and if the damage is slight scoring on a journal, a nick here and there, you should be OK with fresh bearings.

If the whole journal is galled, it won't last long.

[This message has been edited by NEPTUNE (edited 01-21-2013).]

The problem started because of,

Dexcool or whatever that crap is called it blew a manifold gasket and let coolant into the oil. Evidently the previous owner never got it fixed after it happened or never realized it did happen.

My buddy bought the van and it sounded great, until he changed the oil. So evidently they put something in the oil to quiet the noise and that in turn just made the problem worse.

It really is a shame because the thing has fewer than 100K on it and he loves it, picture perfect as far as the outsides go but the crank is toast.

Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

He'll have more problems than just a scratch on a crankshaft.
A salvage yard engine would be my best low buck $oloution.
Sometimes you gamble on a used car and come out with gold.
Sometimes you don't.
R&R an engine in a van is not something I would want to do at my age, but it can be done...

[This message has been edited by NEPTUNE (edited 01-21-2013).]

Emery cloth on a main journal? Yes, I've done it on a scored journal --just to enable me to be able to roll in a set of std main bearings. It's a crap shoot whether it will hold up or not:

Depends on the kind of damage you are talking about. Sounds like the coolant mix got in the oilpan and caused the bearing material to disintegrate to some extent. In that case, you "might" be able to smooth the main journal up enough to hold a bearing ok, but if the main was worn so bad, that it oil starved the nearby rod bearings, those crankshaft rod journals will likely be worn egg shaped, and you will never get them back into round with emory cloth. As you use the emory cloth, it will be taking material off both the high and low sides of the journal, just making the whole thing a tiny bit smaller, but not changing the rofile--iow, it won't be getting rid of the eggshape, unless you have eyeys with a built in micrometer. I know I don't.
Dunno what engine you are looking at, but some you can't get the rear mains out with the crank in the engine and/or engine in the vehicle. How would you get to the rear mains?

IF, it is just a case of a bearing surface being somewhat scorched and rough all over from driving a short while without oil, and the bearings started to heat stick to the journal, you may get by with cleaning 'em up with emory cloth, but I can't see anyway you will ever be able to take enough metal off the worn journals to be able to roll in an over size bearing. That would take 9 forevers.

Did it once on a SBC 400, lasted about 3 months

I've done it on a 2.7 liter Sebring, I bought it for cheap with a rod knock. Investigation showed it had a partially spun #2 rod bearing. It had some scoring that you could catch a nail on. So I took some fine emery cloth wrapped it around the journal and polished it out. I got a set of new rod bearings and plasti-gauged it. It was within specs so I ran it. I've put about 15k on it without a peep. It's a convertible that at the time booked for around $5500 and I picked it up for $400 plus their service bill. -Jason

[This message has been edited by Fierofreak00 (edited 01-22-2013).]