Random Tinkling Noise - AC Related (I think)

[Scharbag]

So, my car has a metallic clinking/tinkling noise that sounds kinda like a heat shield making noise once the car is hot. It is present at idle, gets a little worse with just a little throttle and seems to either go away or is too quiet to hear under load.

Me and a buddy threw it up on a set of quickjacks last night and took the skid plate off. With a stethoscope, it was clear it is not coming from inside the engine. Neither of us could really track it down as it is not consistent. To both of us, it sounded like it was coming from the rear part of the engine. It is not gearbox rattle as with the clutch in, it still made noises.

So, my buddy tells me to shut off the AC and blamo, the nuisance noise goes away. Turn the AC on, and it will randomly make the noise. Turn it off, and again, no more tinkly/clinkly BS noises.

I searched a bit and found people mention the compressor can sound pretty bad when failing but it does not seem to be the compressor (not clunky enough, way too metallic it seems). I will double check today but the noise did not seem to be from the front area of the engine.

My car has zero codes in memory so this is a noodle scratcher. Anyone else ever suffer from this type of noise?

Any help would be greatly appreciated with this annoying little issue that just cropped up yesterday.

Cheers,

[atopa2002]

The pulley on the compressor can rattle

[Ajolives]

I've also heard the pulley can clink/rattle a little, question is is can that resonate to the back of the engine where you and your buddy heard it.
Maybe the extra load on the engine from the compressor is causing vibrations?

The usual culprit in the rear of the engine is the exhaust gasket, but the A/C coming into play does add a twist…

[Redd]

AC on causes additional vibrations from the engine that may be randomly causing the noise. The AC system may not be the case, but it may be the trigger.

As mentioned, rear of engine is usually exhaust. I'd give the exhaust system a good whack with my fist and see if there's any rattling. Also check the heat shields around the exhaust. I once tore my entire dashboard apart chasing a random rattle only to find out it was an underbody heatshield which was missing a screw.

[buldogge]

Any chance it's as simple as the bearing on the blower fan/wheel?

Moisture tends to get in there and the small bearing fails over time and becomes noisy...can be tested by dripping some light oil on the shaft, thru the filter opening, and see if the sound goes away.

Easy replacement, and not much $.

Just a thought.

-Mark in St. Louis

[Scharbag]

Originally Posted by buldogge

Any chance it's as simple as the bearing on the blower fan/wheel?

Moisture tends to get in there and the small bearing fails over time and becomes noisy...can be tested by dripping some light oil on the shaft, thru the filter opening, and see if the sound goes away.

Easy replacement, and not much $.

Just a thought.

-Mark in St. Louis

Do not think so but I will double check.

Cheers,

[Scharbag]

Originally Posted by Redd

AC on causes additional vibrations from the engine that may be randomly causing the noise. The AC system may not be the case, but it may be the trigger.

As mentioned, rear of engine is usually exhaust. I'd give the exhaust system a good whack with my fist and see if there's any rattling. Also check the heat shields around the exhaust. I once tore my entire dashboard apart chasing a random rattle only to find out it was an underbody heatshield which was missing a screw.

I will take a good poke around there ASAP. Everything was pretty hot last night and it was getting late - this sounds like a Saturday task.

[omgzirra_exe]

pretty normal sound to have and its something that does occur over time. if you have upgraded pulleys this certainly does affect it also.

[serranot]

Water from the condensate drain dripping on a heat shield and vaporizing?

[Scharbag]

Originally Posted by serranot

Water from the condensate drain dripping on a heat shield and vaporizing?

No. Checked for that. It is too clinky. And I am starting to think it is nothing to do with the AC as it can happen regardless of AC being on or not.

[Scharbag]

Originally Posted by Redd

AC on causes additional vibrations from the engine that may be randomly causing the noise. The AC system may not be the case, but it may be the trigger.

As mentioned, rear of engine is usually exhaust. I'd give the exhaust system a good whack with my fist and see if there's any rattling. Also check the heat shields around the exhaust. I once tore my entire dashboard apart chasing a random rattle only to find out it was an underbody heatshield which was missing a screw.

Been busy with other stuff. I hope to revisit this soon.

Cheers,