Engine guys inside

[94 formula]

I finished tearing down my motor tonight and didn't like what I found. The three middle main bearings were spun and have worn down the crank probably past the point of having it turned. EVERY rod bearing was atleast worn past being acceptable with most having small chunks ripped off of them and deep grooves worn in the inside and outside of them. It almost looks like someone replaced the bearings without ever turning the crank but I have had this car for close to 30k miles without a problem internally except once in awhile it would drop from around 60psi to 50 or 55 psi at WOT and around 4k rpms. Once my motor started making a noise and having the oil pressure drop I didn't drive it and maybe ran it for a total of 5 minutes at idle for diagnosing (at idle it held 20-25psi of oil pressure). How could have all the bearings spun at once like this? Should I just buy a short block and start over? Were LT1's know for having a soft crank? My cam looked perfect and the pistons and walls look fine. I'll post some pictures soon. Any advice is appreciated!

[Trash man]

just get a new crank(cough 383 time cough) and new bearings and go from there

[94 formula]

Thats what I'd like to do but I'm scared that since that many bearings are spun its something more than just a bearing going bad. I'll get the pictures up soon but its not just small grooves they are torn up and the crank is torn up, I'm worried if I just replace the crank and bearings this is going to happen again.

[DeWynter]

Well if you go to a stroker you will have to have the cylinders bored .030 over anyways, so why not have the machine shop line hone the saddles and caps? Then you would start with a straight place to lay your crank. Could have it mag fluxed to to look for cracks or deformation.

[94 formula]

I would love to have it bored and do a 383 but really don't have the money because of all the hidden costs. I looked into it but after a 383 I'll want heads and a cam which I'll need a better valve train to support then probably bigger injectors, clutch, how long will the rear hold ect. My main goal right now is to get the car back to running order without having to drop thousands into it. I just can't understand how all of the bearings could be bad like they are.

[fastTa]

When you start to lose oil pressure, all of the bearings are affected. The middle 3 main bearings take the majority of the beating from the crank due the nature of crank deflection created by the centrifugal and centripetal forces. More than likely the #2,3, and #4 main bearings started to walk first. Then once that happens, you will get a significant increase in crankshaft harmonics that aren't always obviously detectable.

I'll explain more when I get home from work......

[94 formula]

When you start to lose oil pressure, all of the bearings are affected. The middle 3 main bearings take the majority of the beating from the crank due the nature of crank deflection created by the centrifugal and centripetal forces. More than likely the #2,3, and #4 main bearings started to walk first. Then once that happens, you will get a significant increase in crankshaft harmonics that aren't always obviously detectable.

I'll explain more when I get home from work......

Whenever you get the chance I'm all ears...well eyes .

[fastTa]

Whenever you get the chance I'm all ears...well eyes .

Sorry....super busy week!! I'll type it up when I get home tonight.

[fastTa]

Basically what I was trying to say was that it sort of a vicious cycle once a few of the main beariings start to walk and you also start to lose oil pressure. Especially if a few of the cam bearings get just slightly turned, the oiling orifice in the cam bearing will become misaligned with the oiling orifice in the block. It all just gets ugly after that.

You could just have the main bores line honed and re-install the caps if you want to save money. But you need to make sure they do the line honing correctly. First of all they should have a quality machine that can first grind a reference surface square to the parting face of the main bearing cap. The parting face should then be ground from this reference surface that has already been accurately squared. The parting face and bore wall registry is now maintained. Grinding the parting surface of the main bearing caps leaves all the main bearing bores smaller when the main caps are bolted back in place. The main bearing bores are then line honed.

It would be a good idea to the cam bearings all well and maybe have the cam journals polished as well.