2009 Pontiac Vibe GT 2.4l... Mysterious, Intermittent noise.

[Jonas]

Hi All. 2009 Pontiac Vibe GT 2.4l 260k

I've been chasing this noise for a few weeks now. Earlier today, I had the belt tensioner replaced (which was needed) and drove home with no noise. Later today, I went driving, and the noise came back. It's inconsistent in both sound and when it occurs. All the reciprocating components are smooth, quiet, and have been replaced recently. The belt is new-ish too and in good shape. I'm stumped at this point. Any ideas?
Thanks,
Jonas

Both of these videos were shot within a minute or so of each other.

 

[spasm3]

What brand tensioner and idler pulleys. Sounds kind of like an idler pulley with bad bearings, were they all replaced?

Water pump?

 

[Fabulous50s]

If you run it with the belt off does it make any noise? That would be my first step in diag.

 

[Jango]

It is named the Vibe for a reason. You found it.

 

[Jonas]

What brand tensioner and idler pulleys. Sounds kind of like an idler pulley with bad bearings, were they all replaced?

Water pump?

The idler pulley is a Gates and the tensioner is a Litens. The water pump was replaced a few days ago with an NPW. It made the noise with the old water pump installed too.

 

[Jonas]

If you run it with the belt off does it make any noise? That would be my first step in diag.

I have and it didn't make any noise, but it doesn't always make noise until after I've driven a while.

 

[Jonas]

Exhaust leak maybe?

 

[Nukeman7]

The idler pulley is a Gates and the tensioner is a Litens. The water pump was replaced a few days ago with an NPW. It made the noise with the old water pump installed too.

Is the Gates idler pulley newly replaced or an old part?

It sounds like a bad bearing in the idler pulley if the Litens tensioner is new along with the NPW water pump.

 

[Jonas]

Is the Gates idler pulley newly replaced or an old part?

It sounds like a bad bearing in the idler pulley if the Litens tensioner is new along with the NPW water pump.

The idler pulley was replaced not long ago. I'd say no more than 2 years.

 

[Danno]

Toyota engine? Recall a similar on Toy engines. Need to use OE parts on that kind of work.

 

[Jonas]

I just ran the engine for about 5 minutes while inspecting everything and it was smooth and quiet the whole time. I turn the AC on and off and it didn't make any noise. That's what's so confusing.

 

[spasm3]

Aluminum blocks transmit sound , so you get fooled about where its coming from. I would check every accessory bracket bolt, heat shields, and maybe get under the car and listen.

 

[Nukeman7]

The idler pulley was replaced not long ago. I'd say no more than 2 years.

Was a new dust shield installed with the Gates idler pulley? This TSB suggests not to reuse the OEM dust shield since it may interfere with the pulley's operation.

 

[Jonas]

Was a new dust shield installed with the Gates idler pulley? This TSB suggests not to reuse the OEM dust shield since it may interfere with the pulley's operation.

that's a good catch, thanks. I don't think it's the problem, though because the bulletin says sometimes it needs to be reused other times not. Also it says it may prevent the pulley from turning, but the pulley spins freely and quietly by hand anyway.

 

[Jonas]

*Update* I just noticed that my long-term fuel trim was negative 10 at idle, and on average, negative 5 while driving. I know vacuum leaks typically cause high fuel trims, but does this give anyone any useful information?

 

[Jonas]

*Update 2* I think I found the exhaust leak. The bracket that holds the Catalytic converter in place is broken off, so there's a hole right under the honeycomb. JB Weld?

 

[Jonas]

I put the broken part back in place like a puzzle piece and tightened it back down. I'm wondering if I could just put some exhaust paste on and around it to seal it.

 

[GR_CoB]

To me definitely sounds like an exhaust leak or loose/cracked heat shield, based on owning multiple vehicles with that 2.4L. I love the 2AZ-FE.

 

[researcher]

I put the broken part back in place like a puzzle piece and tightened it back down. I'm wondering if I could just put some exhaust paste on and around it to seal it.

View attachment 270036

Muffler shop *might* be able to run a weld line there to attach and seal that area. have to contact a muffler shop see if they can help

I'm not sure if JBweld can put up with the temps a cat produces. or exhaust paste.. see if it's good for 1200+ degrees