Toyota Repair: Should I Repair Or Replace?, tensioner pulley, rod bearings

Question
Hi Ted,
I have a 1988 4 Runner in excellent condition w/106K,3VZE engine. Work completed in the last 3 thousand miles new timing kit, valve cover gaskets. . I am still leaking some oil which I believe is coming from a camshaft seal.I also can hear a very low thumping after the engine is warm. You can hear it for a very short time upon acceleration and then it stops. I did notice this after the timing replacement. I have read one of you previous threads and it matched one exactly and you spoke about excessive clearance in the main or rod bearings. Here's were I need you advise should I replace the engine or repair it? I am not sure what to do, although the engine runs great and does not burn any oil.I would like to keep the original engine  if possible since the mileage is low for the year. Thanks very much for your help.

Answer
This can be repaired by replacing the engine main bearings or only the #1 main bearing wich is the cause of the noise, if it's a 2WD it can be done with the engine installed by removing the oil pan and loosening the crankshaft main bearing caps, the front bearing can be pushed out and replaced, the bearings are numbered, the bearing you should install is a number 5, this is the smallest size available and will take up the extra clearance, if you read some of my earlier posts on this you will know that this worked for me, unfortunately mine was a 4x4 and I had to remove the engine so I just replaced all the bearings as well. You may also try to release some of the tension on the timing belt by adjusting the tensioner pulley and releasing some tension on the drive belts,the reason the noise comes up after replacing the timing belt and the drive belts is that there is more tension on the crankshaft which causes the noise