Possibly a spun bearing? what else could it be?

[Shipe12]

ok so i was getting off the highway and i felt a big jerk in the engine, almost as it was going to sieze and then i started to hear a loud knock so i pulled over and got towed home. The guy who towed it said it sounded like a spun bearing. I checked timing and its good. The oil level was good also. So i drained the oil nothing in the oil...i then dropped the pan and there was tiny tiny pieces of (what seems to be metal) that gave the little bit of oil that was in there a grey tint. i have not found any big chunks. So with the oil pan down im not to sure as where to look futher into the investigation. Any help would be appreciated. Thanks!

 

[Oliver@Slowboy]

pull the rod caps off (be sure to note the direction and rod that the cap came from) and report back.

-Oliver

 

[Memphetic]

Spun bearings aren't typically sudden like that, nor will you feel them. Before you pull the rod caps, see if you can physically move any of the rods back and forth - if you can, it's a big indicator of a spun bearing. Oil clearance is .0008-.004", which you won't be able to notice at all. However, if the bearing is spun, you'll be able to visibly see the movement.

If you can't move anything, but still feel determined that it's a spun bearing, pull the rod caps. Check for unusual wear or shearing.

I thought I had a spun rod bearing on my motorcycle - sounded exactly like it, had the same properties (for the most part, except it would tick only on acceleration and not decel and the noise was coming from the middle of the engine instead of the crankcase), and it ended up being loose nuts on one of the header pipes. So, all may not be lost - but don't hold your breath, unfortunately.

Honestly, to me, it seems like more of a drivetrain situation being that there was a big jerk.

 

[Shipe12]

ok so i was going to pull the rod caps and i noticed a little springy looking piece of metal in the oil screen(the little thingy that hangs down right there) what could that be? And then i moved on to remove the rod caps i removed the 2 bolts and i cant seem to get it off, is there a certian way or technique to get it off? Also what are the torque specs for the rod cap bolts?

Also about it being a drivetrain issue...if it was would it affect how the engine runs because it felt a little sluggish and it also knocked low at idle and when reving it got louder and u could hear some klunks.

 

[1fast fwd]

You have to wiggle the cap back and forth. Take a rubber mallet and bang the sides back and forth. if that doesnt work, CAREFULLY take a screwdriver and work it side to side and you will get it off. You have to check the shop manual for torque specs. I used Eagle rods in my build and used their numbers. Sorry cant help you on that one Good luck and report back with your findings

 

[C3L1CA]

Spun bearings aren't typically sudden like that, nor will you feel them. Before you pull the rod caps, see if you can physically move any of the rods back and forth - if you can, it's a big indicator of a spun bearing. Oil clearance is .0008-.004", which you won't be able to notice at all. However, if the bearing is spun, you'll be able to visibly see the movement.

By "back and forth" do you mean up and down on the crank or side to side?

I just bought a new car and the guy claimed to have rod knock. However when taking it apart 2 flex bolts fell out and most of them were backed out. I don't want to mess with the bearings if I don't have to. I also never heard the car run so I can't say for sure what it sounded like