2002 5.3 Crank appears to wobble at idle

[OKYukon02]

Greetings everyone, and happy Easter if you observe it!

Just picked up another Yukon. Also a 2002 like my first. After taking off the splash shield to change the oil, starting it up and checking to ensure no leak, I noticed the crank pulley appears to “wobble”. I can’t tell if it’s an optical illusion or actually wobbling. And if so, is it normal? My other 2002 does it as well. Never noticed it before, just looked when I noticed this one did it. On both, it disappears immediately if you even rev it 100 RPM off idle.

Runs smooth, no leaks anywhere. No issues with vibrations or anything I can feel as far as harmonics go. No wear on the belts, no squeaking or abnormal wear on any other pulleys. Anyone else seen this? These two are my first 5.3 vehicles. They both do it, one with a brand new motor and the other (in the video) with 125k on it.

Thanks everyone, have a great day!

 

[Tonyrodz]

Does this look similar to yours?

 

[zraffz]

Does this look similar to yours?

I have never paid attention, do these balancers have a rubber insulator?

 

[Tonyrodz]

I have never paid attention, do these balancers have a rubber insulator?

No clue. This is my 4.8 Express van.

 

[OKYukon02]

I have never paid attention, do these balancers have a rubber insulator?

They do appear to have rubber insulators. My two 5.3s anyway.

Tony, your video actually looks like less wobble/wiggle to me, but I don’t have any noise associated with mine.

I may spend Monday looking at a few used 5.3 trucks just to see. I suppose if I see a few more doing it I’ll just chalk it up as normal and not worry about it.

 

[zraffz]

I'll look at the 5.3 on my engine stand later on. If they have a rubber insulator, it is possible that the rubber is broken and distorting the pulley. It was common practice when assembling the old small/big blocks to verify that the rubber insulator didnt break. This would allow the pulley to rotate on the hub and throw off the timing marks.
You don't necessarily have to feel this vibration either.

 

[OKYukon02]

I'll look at the 5.3 on my engine stand later on. If they have a rubber insulator, it is possible that the rubber is broken and distorting the pulley. It was common practice when assembling the old small/big blocks to verify that the rubber insulator didnt break. This would allow the pulley to rotate on the hub and throw off the timing marks.
You don't necessarily have to feel this vibration either.

Is it detrimental at all to the internals? The crank? It’s bearings? No problem throwing a pulley on there, but no idea how long either have been doing this and wonder if I need to examine for any issues running like this may have caused.

 

[SnowDrifter]

Is your harmonic balancer bolt tight?

 

[OKYukon02]

Is your harmonic balancer bolt tight?

It is indeed.

 

[zraffz]

Is it detrimental at all to the internals? The crank? It’s bearings? No problem throwing a pulley on there, but no idea how long either have been doing this and wonder if I need to examine for any issues running like this may have caused.

I honestly don't know. The harmonic balancer does exactly what its name suggests; it reduces engine vibration. I suppose in an extreme circumstance that it could prematurely damage main bearings but I doubt it.

I'll be honest with you, I don't even know how to verify if the hub has spun on these motors, they don't have timing marks (or is that the purpose of the dot on the crank?).

If you elect to take a chance and change it anyway, enjoy removing that balancer bolt. It's like 155 ft lbs.