Is this the sound of rod knock?

[buckwild27]

Poking around with the stethoscope and the sound seems most prominent from the starter. The ticking sound. It also sounds like the starter is spinning while the motor is running, is this right?

No the starter should not be spinning when the engine is running.

 

[RST Dana]

Poking around with the stethoscope and the sound seems most prominent from the starter. The ticking sound. It also sounds like the starter is spinning while the motor is running, is this right?

Not for long if it is….

 

[Dustin Jackson]

I don’t know if this has been said yet but the starter can go bad allowing the starter gear to make contact with the flywheel when the motor is running making all kinds of sounds

 

[rdezs]

Sounds like you better replace that starter asap, before it royally screws up your flex plate

 

[Doubeleive]

easy enough to pull the starter and check it out, if it slides around when you flip it back and forth that's no good.\
be sure to disconnect the battery 1st --->>>

 

[jeremiahm]

Pulled the starter and it makes fun noises:

Flex plate teeth are good and bolts are tight. Going to get a new starter now. This one works, but that doesn’t sound right.

 

[Dustin Jackson]

@jeremiahm How awesome would that be if that fixes it, going from rod knock concerns to tiny starter issue

 

[jeremiahm]

The heavy knock seems to be gone now and I didn’t realize how much my starter was struggling or how loud it was!

Still have my at speed ticking.

I will chime back in after a few days of driving.

 

[Doubeleive]

The heavy knock seems to be gone now and I didn’t realize how much my starter was struggling or how loud it was!

Still have my at speed ticking.

I will chime back in after a few days of driving.

u-joints? worth checking anyway.....

 

[West 1]

Rod knocks have a rythm that does not vary, it is the same every time and only changes with RPM change.
Yours seems to vary, others mentioned a flex plate issue and they may be correct. You might check the torque converter bolts to be sure they are tight and look for cracks in the flex plate. They sound terrible when they break. You can quiet a rod knock normally by pulling off the plug wire on the bad cylinder.

 

[strutaeng]

Pulled the starter and it makes fun noises:

Flex plate teeth are good and bolts are tight. Going to get a new starter now. This one works, but that doesn’t sound right.

I had the starter go out like that on my 06 Suburban last year. It sounded like rod nock. I took off the accessories and even the manifolds. I finally crawled down there and saw that the starter gear wasn't fully retracting, making a metallic noise when it was ridding on the flexplate.

Starter sounded just like your when I shaked it.

 

[jeremiahm]

Took a long drive up to camping this weekend. Rod knock sound is gone! Still chasing my ticking at speed. Changed my oil and cut open the filter, seems clean, no metal shavings or glitter or particles. So I am more confident in the bottom end saying together. Next step is pull the valve cover and check valve train to find this tick.

Thanks all for the insight.

 

[jeremiahm]

4 Spicer u-joints and new CV's installed two months ago. Flex plate and bolts seemed good on inspection when starter was out. Cut open oil filter during a change last weekend and no glitter!

 

[dkad260]

Still chasing my ticking at speed.

I assume you can you hear it while driving?
Does it sound like this outside the vehicle? Starts at about 15 sec. Mine was a worn rocker. I could not really hear this while driving.

 

[jeremiahm]

Here is what it sounds like at Idle and warm:

I can hear it while driving, but it looses its distinction when being recorded.

 

[OBSandaNNBS]

Here is what it sounds like at Idle and warm:

I can hear it while driving, but it looses its distinction when being recorded.

All I can hear are your injectors? Mine are a bit loud too.

 

[Dustin Jackson]

Sounds fine to me

 

[jeremiahm]

I finally have a good recording of the tapping. This is at about 35 miles an hour under a light load from inside the car windows up. I do not get this sound unless I am under load and is hard to hear until about 30mph.

 

[Geotrash]

I finally have a good recording of the tapping. This is at about 35 miles an hour under a light load from inside the car windows up. I do not get this sound unless I am under load and is hard to hear until about 30mph.

This one is a puzzler for me. Doesn't sound like piston slap to me as my L92 does that when it's cold and it's less of a sharp rapping and more like the dull thud of a dead-blow hammer at high frequency.

Hmmm... assuming you have 3.42 gears like most of these do, your driveshaft would be spinning at around 1450 rpms at 35 mph, which translates to a frequency of about 23 hz. So that's another possible source of the rattle - either a worn u-joint or something touching the shaft. I would expect a rod knock - even a mild one - to be louder than that. A few other possibilities that come to mind:

1/ The harmonic balancer on these engines has a rubber isolation ring sandwiched between the belt grooves and the center of the pulley. It's common for that rubber to degrade and generate noise at crankshaft rotation speed.

2/ A loose flex plate bolt or a cracked flex plate could also manifest as a noise at crankshaft rotation frequency, but I would expect that to be audible with a stethoscope at the bell housing.

3/ As has already been mentioned, a loose piston wrist pin could also be a source, but I would eliminate the other external possibilities first.

4/ Finally, some folks have had their timing chain tensioner fail and start making noise, so that's another possibility. A stethoscope on the timing cover would reveal that one also.

 

[jeremiahm]

One last video. It is much louder in person. Driver side reflecting off of a concrete divider. Does it still seem to be lifter noise? It is only under load that I hear it. Thanks again all!