PeachParts Mercedes-Benz Forum - View Single Post

Cervan · #37 07-20-2008, 01:10 PM

Quote:

Originally Posted by jt20

http://www.peachparts.com/shopforum/showthread.php?t=223898

Sloppyjoec, My issue is a little different. There was no knock presesnt which provides me a much higher chance of replacing the crank and bearings with success. As Cervan was explaining, my clearances in the rod bearings have not yet been worn to a state that allows for 'slapping' of the crank surface against the rod bearings. There is a good chance that my rod caps are still undistorted.

If you have a knock present, you need to get under that car with a stethoscope at least, and listen for noises against the upper oil pan. You can drop the lower oil pan to check the bearings on #2 cylinder / rod to confirm damage before engine removal. (#1 can also be done, but must remove oil pump).

I have done a series of compression tests before taking the engine out and deciding to fix it. I agree with you completely, i would totally be wasting my time if I needed an entire shortblock.

As long as your crankshaft mic's out good (you need to measure it, the surface can be reconditioned) you can simply buy new bearings and have the crankshaft (or you can do it yourself) polished to remove the surface blemishes. You also need to check for "ovaling" of the crankshaft, so check it in three or four points on each journal.Retiming isnt that bad and its so much better to know that everything is good on the bottom end than to have something go wrong just after you got it back together. As long as you did not spin any bearings, your rod end caps will be in perfect shape, the spinning of the bearings removes material from the ID of the rod's.

All you need to do is make sure that your clearances are correct, the crankshaft is smooth, and you have plenty of oil pressure and you will have no issues.