Let’s play a round of “Name that sound!”

[1-8-4-3-6-5-7-2]

1997 C1500 4.3

Just wondering if anyone knows what this sound is and/or what part is likely making it? It sound like it’s coming from the back of the engine… distributor area.

Edit: engine runs rough at higher rpm’s and will give a p0304 code

Turn your volume down low!

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[SAATR]

Sounds like she sucked up a sheep.

 

[grampadirt]

What does it do when the engine is revved a little?

 

[VIKING_MECHANIC]

Vacuum leak maybe?

 

[Schurkey]

First Guess: Vacuum leak

Second Guess: Failing bearing in an accessory--alternator, idler pulley, etc.

Grab a cardboard core from a paper towel roll, use it as a reverse-megaphone by holding it to your ear, and waving the open end around the engine bay.

Or start investigating the misfire on #4, and see if the misfire and the noise have a common cause.

 

[1-8-4-3-6-5-7-2]

What does it do when the engine is revved a little?

It speeds up with the engine. Also see next reply for more info

 

[1-8-4-3-6-5-7-2]

First Guess: Vacuum leak

Second Guess: Failing bearing in an accessory--alternator, idler pulley, etc.

Grab a cardboard core from a paper towel roll, use it as a reverse-megaphone by holding it to your ear, and waving the open end around the engine bay.

Or start investigating the misfire on #4, and see if the misfire and the noise have a common cause.

It’s really intermittent when it does it and hasn’t done it for several months, but today it seems fairly constant.

It definitely sounds like it’s coming from the rear of the engine and the noise in the video gets louder back there as well (actually just remembered, last time it did this I removed the accessory belt and the noise continued). I’ll investigate a vacuum leak.

 

[1-8-4-3-6-5-7-2]

Vacuum leak maybe?

Thanks, will check that out

 

[1-8-4-3-6-5-7-2]

If i accelerate really fast the engine will start to miss out real bad and the whole truck bucks around. After about 20 to 30 seconds it will go back to normal. It’s never had as much power as I’d expect it to have… I think my old 95 TBI was stronger.

 

[grampadirt]

Suggestion...climb under your truck and listen for the noise...is it louder? Sounds like a trans noise.

Wonder what kind of a noise the distributor/cam gear would make just before it goes completely? Doesn't that sound a lot like a gear powered timing set?