Chevy 3.5 engine tick

Question

I have a 08 Chevrolet Impala with a 3.5 with 70k miles. There is a tick that corresponds to engine speed. It's a pronounced tick but I highly doubt its piston slap or rod knock.  It seemed like an exact match for a noisy lifter. I replaced lifters and same thing.

The noise seems to come from the upper part of the motor, maybe slightly to the rear, below the plenum. Oil level is fine and no low oil pressure light.

What else could cause engine tick?

Video may tell more

https://youtu.be/EZjPWnCwGTk

UPDATE: 
Pulled the rod on #6 and found this on the bearing.

Touching the crank, feels smooth. Nothing like the rod bearing. Need to mic it though.

UPDATE 2 : Several rod bearings are similar to this but not quite as bad. Main bearings are fine. What could have caused this?

SteveRacer · Answer

Wow!

What do the crankshaft rod journals look like?  That's some serious bearing damage.

What caused it?  Hard to say, other than a lack of lubrication.  Which may have been promoted by piston slap...

I would be replacing ALL the lower end bearings, and potentially having the crank pulled and polished/reground if there is anything short of a mirror finish on any crankshaft bearing surface.

Also, what does the top end of the #6 rod look like?  I'd knock out the wrist "gudgeon" pin and check the bushing.  Perhaps that is what is causing your tick.

Chevy 3.5 engine tick

One Answer

Add your own answers!

Ask a Question