rod bearing symtoms

[mtn goat]

Well, it sounds like most people are pointing toward my bottom end...not that one...for the source of my knock. :( :( So, unless I hear a better idea (see Help me diagnose this knock) I will pull the oil pan and take a look. However, what should I be looking for? A friend of mine suggested that i have a spun rod bearing..Are problems with the bearings (and whatever else is bad down there) something I can see and not have to make detailed measurements with a micrometer? Thanks...I am sad my jeep is sick :(

[joe]

Serious scoring of the bearing surfaces or any copper color showing through is a dead give away.
If it looks decent and since you've got the caps apart anyway do a plasti-gauge test to see if the clearances are in spec but if you really do have a rod knock just looking at the bearings will be obvious.

[Crazy_Jeepman]

Well since you have an audible knock as well as a screeching sound you will see it imediatly no Micrometer or plastiguage will be neccesary. Pull the pan with good light look at all the rod caps they will look oily brown to black. The one with the spun bearing will be the one(s) that look dry different looking from the rest, grab ahold of it and try to move it side to side if you get movement that is the knock, it will move front to back this will be normal. Pull it first then look at the shell bearing in the cap then the crank journal. Scoured or heat marks will indicate lack of oil and is the problem rod. As -joe mentioned if the bearings look ok do a plasti-gauge test to see if the clearances are in spec. By the way if you find it is a spun rod bearing it will not be a simple matter of replaceing the bearing. You will need another rod and the crank will need to be replaced or reground. Good Luck!

[ November 12, 2001: Message edited by: Crazy_Jeepman ]