What is this noise???

[chrispy]

Hi fellas,

Over the past month, I've noticed a strange noise when in reverse, primarily when holding the truck in place with the brake. It is getting louder as time goes on and I hear it in park/neutral now, sometimes drive when idling, just not as bad as reverse. It also does it for a second after I kill the ignition as the motor is dying down.

The best way I can describe is a "ryhtmic squeaking". I thought it was coming from the engine bay, but I think I tracked it to the area near the bellhousing under the vehicle. I took a video while I shifted from reverse to park. Sorry no visual, I was trying to hold the mic close to the source.

My research indicates possible flex plate issue, but all the videos of flexplates I've heard are more of a rattle than a squeak, so I'm not sure. What do you think?
https://www.youtube.com/watch?v=DbBLpvwYdjM&feature=youtu.be

Truck is a 1994 c1500 4.3 Auto.

Thanks in advance!

 

[1500z71]

Fan belt? Can't locate it through video, simplest stuff first, that's what my novice self would check

 

[Big D]

sounds like a bearings on its way out to me. shot in the dark guess would be water pump. if you use a very long screw driver and put it near the bearing and place your ear on the handle end of your screwdriver/pry bar...etc if its loud and rough that may be the problem.

 

[chrispy]

sounds like a bearings on its way out to me. shot in the dark guess would be water pump. if you use a very long screw driver and put it near the bearing and place your ear on the handle end of your screwdriver/pry bar...etc if its loud and rough that may be the problem.

I recently discovered a coolant leak that I believe is coming from the water pump, so maybe that's related? I just don't know how I feel about sticking a screwdriver near all those moving parts (fan/belt/ etc).

I could swear the sound was coming from the Bell housing, but it wouldn't surprise me if it was just resonating from somewhere up front. It's just hard to hear and pinpoint from up top due to engine an fan noise.

 

[Big D]

you can put it anywhere on the water pump, the noise will resonate through the casing. the leaking can be related.

 

[chrispy]

I had some time this evening so I probed around with a screwdriver as recommended. I didn't have a very long one, but was able to reach the top of the water pump and listen from the other end. A big jet engine would be the best way I can describe what the sound resembles. After a while if listening it seemed like my ear tuned in better and I was able to vaguely hear the squeaky sound over the rumbling.
I'm going to take the inexpensive gamble and swap out the pump sometime over the next few days. I'll report back. Thanks!

 

[Big D]

I get the best noise results using a screwdriiver where the metal goes all the way through the handle.

they sell very cheap ones at harbor freight, it looks just like this one. https://www.youtube.com/watch?v=U927cYhQXB4

comes in handy sometimes when your trying to figure out whats making noise with no check engine light.

If you want, compare it with another part spinning like the alternator. If both the water pump and the alternator bearing are in good shape, they should sound relatively similar to each other. smooth.

A big jet engine noise with some squeaking.... sounds like your on the right track.

 

[chrispy]

OK the new pump is in, but the noise remains. Bummer...
I'm glad I did I t though, since it was leaking.

New development: Either the squeaking noise got louder, or the new water pump is much quieter, because the noise seems more pronounced than before. I am pretty confident that the sound is coming from the crankshaft pully now, which I just noticed has a bit of a wobble. What would be a remedy for this scenario if that's the case?

Here is another video to give a visual as well as to hear the sound. Note : There has always been sludge around there, but it looks super wet in the vid. That's due to coolant runoff from changing the water pump, so its not like a massive leak or anything.

https://www.youtube.com/watch?v=SRtjfeZPWL8&feature=youtu.be

 

[Dr.Zoom]

And it's not coming from the idler or tensioner? It's hard to tell from the video how much wobble there is(I guess because of the combination of moving the camera and youtube's processing). It doesn't look like much to me. Belts can squeak from misalignment, but I don't hear that. Sounds more like a bearing starting to roar and high pitch muted ring or the start of a screech.

I listened to it again, maybe it is the belt squeaking. Can you look at the belt and pulleys from the side and see any misalignment of the pulleys?

 

[Big D]

have you tried to use the screwdriver trick on the other spinning parts? idler pulley or belt tensioner would be my next guess as too whats making that noise.

I agree the high pitch noise is more pronounced, I think that water pump was on its way out.

I dont think its your Harmonic balancer/Dampner (crankshaft Pulley) in my experience, it causes a lot of noticeable vibration.