Annoying Chattering/scraping Sound

[Minuit]

Recently, my truck has been making a weird sound from the very front, by the belt drive. It runs fine and the sound isn't noticeable when the engine is cold, but gets louder and louder as the engine warms up. When it first starts making this noise it almost sounds like a lifter tick but it turns into a sort of chattering or scraping noise. I'm 90% sure that this isn't coming from the bottom end or the valvetrain - I hear the normal sound of the engine through a screwdriver on the valve cover or head. I'm leaning towards the water pump, but I don't want to just throw parts and money at it.

 

Shaky phone video of the noise:

 

Since that video was taken, the serpentine belt and idler pulley have been replaced, with no real difference notable in the noise.

 

Thanks for looking, and hopefully someone knows what this is. . :MJ 1: .

 

 

[ftpiercecracker1]

Almost sounds like your Mech fan might be hitting the shroud. Something that you can try, remove the serpentine belt and start the truck. If the noise goes away you know its not internal. While you have the belt off i would manual rotate all pulleys to see if you can reproduce the sound. I would also pull the shroud and see if that makes a difference.

[87manche1]

Yea id rule out pullies a/c clutch water pump alt anything on front. Fyi those idler pullies are infamous for bad bearings. Edit didnt see u replaced next a/c clutch or other

[Akula69]

Weird - sounds just like mine when I had a bad idler pulley, but I see you replaced yours already. Did the sound change at all (after you replaced the idler pulley) and put the new belt back on?

[64 Cheyenne]

If I had to guess without actually seeing the truck, I'd have to possibly say

that the HB is coming apart and hitting/scraping the timing cover

or if not, most definitely a bearing from an engine accessory.

I second the opinion of taking the belt off, starting the truck, ruling out

the noise coming from the engine. Could also prove HB is hitting the timing cover.

You could also run it for a while, shut it off, use a laser temp gauge try find a "Hot" bearing.

[64 Cheyenne]

To the OP, your intuition says WP, sometimes your "intuition" can be one of your best tools,

...or your worst if it gets away from you.

[Minuit]

Great suggestions guys. One thing I'd like to point out is that this seems completely temp. related. I.e. it doesn't do it at all in the morning and takes a bit of driving in the afternoon for it to start.

[Minuit]

Weird - sounds just like mine when I had a bad idler pulley, but I see you replaced yours already. Did the sound change at all (after you replaced the idler pulley) and put the new belt back on?

 

Didn't change a bit.

 

Next time I'll get the chance I'll take the belt off and run it to see and I'll also try turning the engine over by hand and see if I can hear it. I can pretty much confirm that the appearance of the noise is directly connected to the engine temperature. Coolant reservoir is full.

 

 

Almost sounds like your Mech fan might be hitting the shroud

 

Checked the shroud, no scuff marks or anything on it. I can also rotate the fan by hand and it has plenty of clearance with the shroud.

[JeepcoMJ]

it doesn't look like you have a/c hoses on that compressor....can you clarify wether you do or not?

 

if not, then the a/c clutch is locked up. that noise sounds like an a/c compressor running open with a locked up clutch

[HOrnbrod]

Get a 3'-4' piece of 1/2" or so vacuum hose. Since it's temp related, get the noise going again (in the afternoon ?) or whenever it makes the noise. Stick one end of the hose in your ear and probe with the other end at all belt driven devices. That'll get you in the ballpark.

 

Also, check the bell housing underneath with your hose "listening device". Sounds like a cracked flexplate problem I once had.

[JFAComanche6]

If I had to guess without actually seeing the truck, I'd have to possibly say

that the HB is coming apart and hitting/scraping the timing cover

I had this problem, the HB slid back and cut a huge griive in my TC cover, but it squeaked like crazy and got quieter the longer the engine ran (due to the metal being removed from between the parts). I'd make sure that HB isn't too close to the engine.

[Minuit]

The AC compressor is hooked up, it's just a weird angle.

 

I listened real close with the hood closed and the center of the noise is right by the HB.

 

Thanks for the hose suggestion! The flexplate sounds fine but 3' of heater line is a whole lot better than a screwdriver, for sure.

 

Thanks a bunch, guys. I'll take everything apart to see about that harmonic balancer later this week. Looks pretty tight even with the mech fan off.

 

 

[64 Cheyenne]

You don't have to take anything apart to check the HB, matter of fact you nearly had the right angle to look at it in your video

although the engine should not be running. Look top down, possibly put a light underneath shining up to see better behind the balancer.

[JFAComanche6]

The HB should look about 1/4-ish inch from the engine.

[Minuit]

Definitely the HB. The rubber holding it together is worn out and the pulley half is maybe 1/16 of an inch off the timing cover when cold and it's scraping the timing cover when it warms up. Thanks, guys.

[64 Cheyenne]

:banana:

[JFAComanche6]

NP man, and don't replace the TC cover if you don't have to like I did (it cracked), major PITA.

[Minuit]

I don't think I'll have to take the TC off, it's only been rubbing for a couple days. Doesn't look fun to get to.

[ComancheKid45]

Its definently an adventure, but its not a real difficult job if you ever have to tear into it ;)

[JFAComanche6]

I don't think I'll have to take the TC off, it's only been rubbing for a couple days. Doesn't look fun to get to.

It's not.