Strange "Chirp" Sound...

[DavidJBlythe]

1985 M1009. I have changed and tightened my belts, replaced alternator (new pulley), and replaced power-steering pump (orig pulley). For some reason, when I'm driving down the road and holding any speed, my truck emits a soft "chirp" (sounds like a little bird) that matches engine RPM. If I release the gas or slowly decelerate the chirp goes away. If I step on gas harder than normal, the chirp also disappears. Any thoughts to what could cause this chirp to occur when the engine is under a load? I did drop the transfer case by moving those spacers down.... other than that, I've left the drive train alone. Thanks for any insight.

-David

 

[Boreal21]

I sometimes get the "angry sparrows" in my Jeep Wrangler, signaling that it's time to lube/change the front ujoint. The chirping changes with engine rpms too. But my Jeep doesn't have hubs, so the front drive shaft is always spinning. Where the 1009 has hubs, I would guess the front DS isn't spinning unless the hubs are locked and 4wd engaged?

Sorry, I've only had my 1009 for a couple of weeks so I'm not exactly an authority

 

[Cucvnut]

why did you drop the T case ? sounds like a wheel bearing

 

[DavidJBlythe]

I dropped the t-case for the lift. It decreased the drive shaft angles to the diffs. I just replaced the front wheel bearings yesterday and really cleaned out all the old gunk in there, and replaced it with new messy gunk Don't know what this chirp is.....

 

[Cucvnut]

It decreases the rear but increases the fronts angle its not the right way to help drive shaft angel.

 

[DavidJBlythe]

Good to know. Do you think it could be related to the T-case or a drive shaft?

 

[hole]

Check all the u-joints/ cv joints. At least on of them is dry and failing. The chirping comes from the needle bearings inside the cup when they stop rolling and start grinding. If this is your DD it wont take long before it fails, it never took too long on any of mine

 

[PropDr]

Although not likely but it could be the needle bearings in one of the planetaries in the transmission. Sounds kind of like a bird caught under the floor boards but is usually intermittent.

 

[Hasdrubal]

Sounds like the needle bearings in one of your u-joints grinding to dust.

 

[DavidJBlythe]

Wow, awesome advice. I'll read up on how to check these. I've never done them before, but that -20 manual is really good. One "General" question... is this a long and/or difficult repair? Also, if I discover that I have a bad u-joint, are they expensive to replace? Again, thanks for the insight.

 

[davidkroberts]

Wow, awesome advice. I'll read up on how to check these. I've never done them before, but that -20 manual is really good. One "General" question... is this a long and/or difficult repair? Also, if I discover that I have a bad u-joint, are they expensive to replace? Again, thanks for the insight.

naah.... they arent anything to replace just get new ones at Napa, Autozone, Oreilles, ect and just replace them. Get new Ujoints with the new cups already installed. Should take maybe 30 minutes a joint for both the rear and front. Its a good thing to go ahead and do for a new (to you) 4x4. They arent really that problematic but you arent going anywhere without it.

 

[suggsdr]

My rear u joint was making that noise so i drop the drive shaft & found rear joint bad i replaced both front & rear joints be sure to get the ones with grease fitting so you can lub them.These veh sit around don't get drove so things will dry out.Got my u joints at autozone.

Suggsdr

 

[ixpacman]

Sounds like an exhaust leak to me.Just a thought
Pacman

 

[DokWatson]

Wow, awesome advice. I'll read up on how to check these. I've never done them before, but that -20 manual is really good. One "General" question... is this a long and/or difficult repair? Also, if I discover that I have a bad u-joint, are they expensive to replace? Again, thanks for the insight.

Nope, all you really need is a BFH and some sockets you don't mind banging up or a vice. Shouldn't take more than 10-15 minutes for the drive shaft. Axle u-joints are a bit more involved, and require at least a spindle nut socket and snap ring pliers to break the axle down to the knuckle and your basic set of tools.

Pirate4x4.Com - Installing a Ujoint

 

[JB]

David if it is what i think you may be talking about I had a chirp sound in the cab and it drove me crazy until my wife figured out it was the blower for the heater/defroster. I had not thought much about it until I stumbled on this thread. If it is my old truck adjust the speed on the fan control and see what happens.

 

[WARWAG]

U joint going bad is my guess.

 

[DavidJBlythe]

Thanks for the link to the 4x4 website. After talking to a mechanic and all of you guys it sounds like it's a U-joint. Thanks for all the advice!

JB- I know exactly what you mean by that stupid fan! If I let the truck sit for about a week or more without running the fan or anything, it will shriek at me for a second or two when I first turn it on. The more I run it, the better it seems to get.

 

[DavidJBlythe]

Still chirping...

1000 miles later. I'm still driving with the birdhouse under the truck. I took a video in which you can clearly hear the sound. It gets really clear about a minute into it.

[media]http://www.youtube.com/watch?v=lal_ORsPlCk[/media]

Update - It now makes this chirp under any circumstance... any gear, moving, etc...
The only quirk is that it directly correlates to engine RPM and seems to fade away when I'm coasting.

Thoughts?

 

[ralbelt]

I could not hear it, but from your description I'm thinking possibly a crack in the flex plate.

 

[MuleMac01]

sounds like a engine issue to me