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


UPDATE: Pulled the rod on #6 and found this on the bearing.enter image description here

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?

  • Google for GM 3.5 piston slap. I think you'll find that these engines may indeed have piston slap. If it was rod knock, you would probably know it, so I would rule away rod knock.
    – juhist
    Commented Jan 25, 2019 at 17:51
  • Could a noisy fuel injector make that sound?
    – asp316
    Commented Jan 25, 2019 at 20:16
  • Yes it could, I used to have 1989 Opel Vectra with noisy injectors. However, the noise could be heard only with the hood open. You couldn't hear it to the inside of the car with the hood down. If the noise can be heard inside the car, I don't believe it's injectors (unless they are extraordinarily noisy).
    – juhist
    Commented Jan 25, 2019 at 20:27
  • I'd probably put a vacuum gauge on it and do a running compression test on each cylinder. That does not sound like a noisy injector.
    – Ben
    Commented Jan 26, 2019 at 2:30
  • Disconnecting spark plug from #6, the noise goes away. Guess I'm getting into it. Anyone know how hard it is to pull the oil pan? Hoping to work on just that cylinder.
    – asp316
    Commented Jan 26, 2019 at 21:54

2 Answers 2



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.

  • Rod journals look fine and mic fine, oddly enough. What's odd is the wear pattern is in a specific spot of the worn rod bearings. I was expecting the wear to be across the whole bearing. What would cause that?
    – asp316
    Commented Feb 8, 2019 at 14:11

A quick net search suggest fatigue or high temperature/melting. All the bearings would need to be examined with magnification to do a real analysis. Part of the problem is that is a severe failure; the original failure may induce other types of failures. Apparently those are babbitt rather than the typical trimetal because no bronze is showing. Babbitt loses fatigue strength at even a couple hundred degrees F. The correct oil viscosity is needed to get design flow across the bearing to cool it; and proper oil pressure. Fatigue does not seem likely in a mass produced engine that has a good history. So basically no help, you need all new bearings and use recommended oil.

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