Toyota Repair: knocking in 3.0 v6, vacuum hoses, main bearings

Question
i have a 94 4runner that i just had the heads reworked because of 3 burnt valves. it runs just fine except for a knock that just by accedent i pulled off the three vacum hoses on the passenger side plenum and the knock almost completely stopped.i put the hoses bavk on the way they came off,but someone else had worked on it before and i'm not sure there right. i have a manual but it's not real clear either.do you have any idea what that knock could be?

Answer
Engine knocking is almost always due to a mechanical problem such as connecting rod/main bearing noise, if the noise is of a low fequency it's most likely the main bearings, higher sounding noises could mean a rod bearing noise(more of a rattle noise), these engines did have some issues with main bearings causing a deep type thumping noise under s slight load, I don't think removing the vacuum hoses has any effect except that by doing so may decrease the load on the engine. I would also suggest having the shop that did the headwork listen and see if they can diagnose the noise based on the information I have provided.