In Reply to: I broke a rod barring and it was spining (more) posted by ADAMK on January 08, 2002 at 13:40:20:
I've seen the insides of a lot of S14's with spun rod bearings. Some are disasters, some aren't so bad. Regardless of the extent of damage though, virtually all are out of spec after the damage was done. I'd say the word "scratch" is a gross understatement. A scratch might be caused by some dirt or other microscopic object suspended in the oil. A more appropriate word would be "gouge". We're talking a traumatic mechanical disaster here. The engine was run w/o the benefit of oil for a brief time. You had metal-on-metal, and the rod bearing seized onto the crank, causing damage to the crank and rod journals.
Heres the risks... assuming the rod bearing was replaced, there's still some extent of damage to the rod and crank. This damage creates a low resistance path for oil to take IE: oil can now squirt out around the bearing and return to the oil pan instead of staying in the oiling system.
This can cause lower oil pressure, and can reduce top end oiling - a downward spiral for overall engine life. If the damage to the rod is great enough, there's now space between the bearing and the rod. That space can cause "hammering" of the new rod bearing since there's now an air gap. In extreme cases, hammering can cause the bearing to crack. It can also cause the rod cap to stretch and distort, thereby allowing the bearing to spin again. If the bearing does spin again, or break apart due to hamering, the rod now has
enough slop to allow the piston to contact the
valves and the bottom of the combustion chambers in the head. At high RPM's, this can cuase the piston to fracture/break apart. If that happens,
kiss that sweet S14 good bye as chances are good that a rod will go thru the side of the block. At this point, the block, crank, rod(s), Piston(s)
and probably head will be junk. I've seen this sort of destruction many times unfortunately.
So, if you were smart, you would fix the problem before it becomes a disaster. If this were strictly a street car driven by a little old lady, and if these motor's were a dime a dozen, I'd say take your chances. But given the fact that we drive these cars rather spiritedly, and given the fact that these motor's are shall we say "pricey", (BMW =Break My Wallet; M3 =Money Cubed) I'd say the risks of not fixing it "right" far outweigh the benefit of procrastinating.
The choice is yours, but now I hope you understand the risks.