Loud *clank* sound from engine - 2007 Tahoe 5.3L

[techbiker]

Ryan- Have you been under the engine when the sound happened? Do this at your own risk, but if the sound is loudest at the oil pan then you can be fairly sure it's a problem in your bottom end.

Best to rule out rod knock now before you rack up any more mileage. The longer you run the motor with internal problems, the more damage you will typically cause.

 

[iamdub]

In that video, I'm not seeing anything on the accessory drive jump or move when the sound is made.

When did this start? Was it after any particular event that you can recall? Only does it at idle?

 

[hound_dog]

Thank you techbiker for the warning, I'm minimizing use.

I did remove the AC compressor belt today (had to do it during lunch). The outside temp was about 65 so much warmer than it has been for the first start up of the day.
I started it up and there was NO clank sound for the 5 minutes that I ran it.
I'm going to let it sit and start it up before 8am when it is at the coldest. We'll see what happens.

 

[hound_dog]

In that video, I'm not seeing anything on the accessory drive jump or move when the sound is made.

When did this start? Was it after any particular event that you can recall? Only does it at idle?

The clank started the day I posted (Friday Dec 29). The engine has had a somewhat rough idle for a couple months. I attributed it to a broken engine mount (driver side) which was replaced on 12/5/17. Also at that time an oil leak was fixed by replacing the Oil Pressure Sending unit AND the Engine Cylinder Deactivation Solenoid. The oil leak was solved by that work.

 

[HiHoeSilver]

Thank you techbiker for the warning, I'm minimizing use.

I did remove the AC compressor belt today (had to do it during lunch). The outside temp was about 65 so much warmer than it has been for the first start up of the day.
I started it up and there was NO clank sound for the 5 minutes that I ran it.
I'm going to let it sit and start it up before 8am when it is at the coldest. We'll see what happens.

Maybe it's just the damn compressor?!

 

[hound_dog]

Yes, I'm hoping that's it.
But I want a repeatable test (it only happens when cold) before I celebrate and get that fixed.

 

[hound_dog]

Alright so I started the engine with the AC belt removed. The temperature was a bit over 50 degrees. After 2 minutes, it clank'd. Well crap.
So I put the belt back on and called the shop for an appointment to look at it. I'll update the thread when I know more.

 

[kbuskill]

Just out of curiosity... did you have both belts removed or just the A/C belt?

 

[hound_dog]

Just the AC belt. I of course needed to loosen the serpentine belt to get the AC belt off.

 

[Dillon2222]

while watching the video at about the time the cluck sound is made, you can see the water pump pulley stop for a brief moment. might want to look into your water pump being replaced if it is still the factory one. just letting you know what i saw during the video. let me know if replacing the water pump works for ya

 

[hound_dog]

Thanks Dillon. I dropped it off at the shop on Monday and will be checking with them to see if they were able to reproduce the sound. Thank you for reviewing the video and looking for a solution. I'll take a look now and look for what you saw. Would be great if that's it!

 

[hound_dog]

The shop said there were misfires in cylinder #1 and #7. Recommended ignition coils be replaced on those two, so they did. Going to pick it up tomorrow and I really hope the clank sound is gone.

 

[swathdiver]

Now how on earth fellas is that clank related to a coil or two with no moving parts???

 

[iamdub]

INB4 "It's still doing it and now the shop wants to try ______."

 

[Dillon2222]

The shop said there were misfires in cylinder #1 and #7. Recommended ignition coils be replaced on those two, so they did. Going to pick it up tomorrow and I really hope the clank sound is gone.

If its cylinders 1 and 7 those are AFM cylinders and you might have a lifter that is stuck, causing the misfire. That can get costly real quick. Still think that noise is coming form the water pump though. JMHO

 

[hound_dog]

So the morning startup after I picked it up...clank! 5 times actually.

Swathdiver was right...how could this solve the clank? It didn't. The coil replacements were to try to solve the misfires (measured). Not sure if it did anything ask the idle is still a bit rough.
I'm at a loss here. Options are to just drive it until it gets worse or won't run....or maybe take it to the dealership and hope they can figure it out. Since everyone has been stumped, it doesn't seem like it will be an easy fix.

Dillion2222: if the sound is coming from the waterpump ....I should just drive it until the waterpump dies. It's not leaking and not overheating so it seems to be doing its job. Agree?

 

[swathdiver]

What do your plugs look like on 1 and 7? Did you get a stethescope?

 

[Scooty]

I had an intermittent clank on my 08 just this winter. My mechanic put on a lift and checked everything that could possibly be loose and found nothing. he then started it while on the rack and thought it was coming from the starter. Sure enough after pulling the starter he saw the pinion gear was not disengaging all the way from the flywheel. It was barely touching the flywheel thus causing the intermittent clank. Replacing the starter fixed it...just my experience.

 

[hound_dog]

Awesome post Scooty! Did yours only do it while cold or also while driving?
Thank you very much for taking the time to read these problem threads and maybe striking gold. I will see what I can do to determine if the sound is coming from the starter.

 

[Scooty]

Awesome post Scooty! Did yours only do it while cold or also while driving?
Thank you very much for taking the time to read these problem threads and maybe striking gold. I will see what I can do to determine if the sound is coming from the starter.

Also while driving. It started the Saturday before Christmas and the local shop I went to was closing early but said he didn't want me leaving on the chance of causing more damage. After he got the starter off you could hear there was something loose in it. He thought the pinion would slide out and hit the flywheel and that would kick it back causing the clank. Again this was my experience ...hope this helps you.