cranshaft damage

[HAVABEER]

how's it going

i'm just about to go pull the sump of my 3s-ge that has the begining's of a spun bearing. once i get the big end off. what should i be looking for on the crankshaft damage wise?

should i be looking out for scratches and marks.....or will be be more of a warped type of damage. will it be noticeable or something that will have to be tested at a machining place?

and what would happen if i just put a new set of bearings straight over the top with out getting the crankshaft machined?


just becuase i've been through a spun bearing before, and it was alot louder then this and the car ran like crap. where this time its nowhere near as loud and the car still seems to go quite nicely?

[Hydra]

Generally you will notice scoring on the crank where the worn bearing is rubbing. I'd stop driving it soon You might only be getting slight noise now but it will get worse.

You should machine the crankshaft if it is scored or marked, by the sounds of it there will be a bit of damage... assuming it's the crankshaft

[slide86]

i seen heaps of engines that have had just the bearings replaced woth no machining. ive done it to a bunch of LS1's and never had a drama.

there will be score marks on teh crank that will be a good indication of the damage. if you get onto it early then you may be ok.

the other thing to think bout is the rods. they may be out of round, caused by the bearing knocking round. this is what happened to my engine. i needed to have the rods, crank machined and installed with 10thou oversize bearings. but i did this cause i wanted it done right, due to large amounts of thrash work the engine will cop.

you should be right, but its up to you. machine work = $$$

[TurboRA28]

My 3sgte had spun a bearing, and the crank was useless.. It didn't look too bad to me, but the engine machiner said no way to machine it down they would have to remove too much from it.

[HAVABEER]

well i got the big end bearing off and to me the bearing doesnt look worn at all...there's a bit of grey discoloration splatted on the inside and thats about it.

here's a photo
[IMG][/IMG]

[slide86]

dude. WTF are those score marks going across the face of the journal. they shouldnt be there???

that might be cause in itself to get the crank machined

[30psi 4agte]

WTF im with slide hope that is just a reflection of the con rod thread on the crank or you will need to get that fixed !

[Andrew162]

I agree, it appears to be the thread reflection from the light of the flash.

[Trent-KE30]

We get rods in all the time that has been spun, the bearing will be welded into the rod and there useless, that pic, looks as though the bearing as become quite hot and scored the outside of the journel, i'd be getting that crank ground asap, and those rods as well,

Trent

[HAVABEER]

yeah that ring of "crud" wipes off by it it fairly rough underneath it. if you run your fingernail over it you can feel it, then its smooth in the center.....and rough again on the other side.

[Hydra]

Bummer Machining time, or pick up another crank