light knocking

[mustang302orange]

whats up guys; i think i blew a main bearing this weekend racing my freind 86 monte ss. there was a big back fire at about 4500 rpm. then i started it later and we heard a little knock in the bottom end but then it went away. buy the way i blew him away by atleast a cars length.. any know a good engine rebuilder.. remember i'm from paterson, nj lets fix this beast asap!!!!!

 

[mustang302orange]

lets get a new chapter over here in nj................

 

[Chevy_Guy]

How do yo know it was a main bearing, a backfire has nothing to do with a spun main bearing. Also never heard a spun bearing that stopped knocking on it's own.

 

[BMad]

How is your oil pressure? A little knock on start up in cold weather with a higher mileage or higher compression engine is not uncommon, and doesn't necessarily mean a death sentence for your engine. If you're worried about a spun bearing, drain the oil into a very clean pan and check for debris. Cut open the oil filter using a chisel or a filter cutter (not with a saw) and check for shavings. Normally if there is damage to a bearing it will show up as shavings or sparkles in the oil or oil filter.

 

[The Bone]

damn beat me to it.....oil pressure and compression test

 

[stanginthe11s]

mains dont knock, rod bearings do. compression has nothing to do with knocking either. a backfire has to do with the engine and therefore can be related to a knocking sound, if there was detonation the rod bearing takes a hit hard and can loosen up clearances quick so there can be rod knock on start up but once the pressure comes up the oil fills the gap, very common thing. also it could be piston slap if the backfire caused damage to the piston or rings.

 

[BMad]

If the rings and pistons are damaged it would show up in a compression check. If the damage was caused in the mains, it may show up in the oil. If you have low or no oil pressure on start up the engine will knock, especially in cold weather. When the car warms up, the knock goes away.