Hey folks, first post here but this site along with the FSM has allowed me to keep my '90 4Runner trucking right along, until just the other day. She developed a knock, it speeds up with RPMs and its audible, maybe even a little louder, at idle. I drove maybe 5 miles after it started, clearanced the valves (one tappet had backed way, way out since last time), started it again--still knocking. Checked compression--175 to 185psi on 1 through 3, 155psi on #4 (#4 is iffy, couldn't thread gauge in but a couple threads due to a cross-threaded spark plug incident from a couple years ago, plus battery was down a little by this point). I cranked it back up, took the stethoscope to it and found it was slightly louder down at the oil pan than up high, though it was clearest on the driver side valve cover retaining nut over cylinder #4! I dropped the diff. and oil pan, found a couple hair-sized brass slivers. Pulled the rod bearings first and they seemed alright--light wear, but new standard size (.000 oversize) bearings plastigaged with flying colors. Went to work on the mains, I started with #3 (the middle one) and as soon as I got the top half out (the nail trick is nice!) one thrust washer fell right out. The front washer fell out, the rear one stayed and is actually locked in so tightly that I can't budge it. My first question: Is this a major concern? I don't fully understand how this washer is retained, though it seems like the crank may have moved forward just a bit thus accounting for the excessive clearance up front. Second question: I know you can get oversized thrust washers--how could I go about gauging their fitment without (God willing) pulling the engine? I need this truck to drive to work daily, right now my wife and I are having to carpool which sucks since our jobs are an hour apart! Thanks in advance.

 

using oversized thrust washers will not work without having the block/crank machined to accept them.

 

Just to clarify, I didn't realize there were 4 thrust washers around the #3 main--two on each side of it, one above the crank and one below. The washers below the crank seem fine, my concern is that the washer above the crank, in front of the bearing, just seems to loosely sit in place whereas the rear upper thrust washer is in very tight. Going to play with it a little more tonight and make sure I'm not missing something, in the meantime any further advice is greatly appreciated.

 

How long could one go with out two thrust washers in a daily driver?