New to this fourm, hope I have this at the right spot.
96 Blazer with 4.3 L Vortec 340k on it. Last week it started making a knocking noise. Brought it to the garage and was told that it sounded like the main bearing but was told to drain my oil and if there was copper shavings in the drained oil that it would mean its 100% the main bearing. I did not find any copper but seem to be sand like dirt in it. Replaced the oil and filters and put a can of cleaner in it but result is the same. Is it a hard job to replace the main bearing? Does the engine need to come out. Any help insight would greatly be appreciated. The knocking noise seems to be present all the time hot or cold you notice it less with speed but I think it’s just because of road noise drowns it out.

 

Do you have an oil pressure gauge? If so, how does it look? Usually, a main bearing problem will result in low oil pressure. A rod bearing may not. I would bet that it is a rod bearing. Still, you are looking at quite a bit of work to get it fixed. I would not drive it again unless you are planning on getting another motor as you can waste the crank...

 

No I stopped driving it until I can decide what to do with it. the oil gauge on the truck is always moving up and down. If I hit the gas it goes up and when I let off the gas it gets lower but most of the time it’s in the middle. So this may not be something I should try and fix on my own?