Chirping Under my Hood

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

Hello everyone. I'm a new member, in fact I just made an account to make this post. Anyway, I'm having a chirp like sound come from under my hood, from what sounds like the viscous heater. I took out the relay like I've seen many suggest on this forum and the problem is still there. I did a little troubleshooting, and the chirping only comes when I put the cool air on. I've been doing some research from this revelation, and I would like to know if the viscous heater does the same job as the ac compressor, or if they're the same thing.

Thanks in advance

.

flash7210 · **Posted:** Thu Mar 12, 2015 3:49 pm

If it chirps only with the AC on, then I would suggest first replacing the belt depending on how old your current belt is.
If not the belt, then I would suspect either the AC compressor clutch/pulley or the belt tensioner.

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

I forgot to add a couple things, I'm in class atm.
I had it at a mechanics trying to chase down the noise. They replaced belt and tensioner.
How would I narrow it down to compressor, clutch, or pulley?
The vehicle is an 06 CRD Limited.

papaindigo · **Posted:** Thu Mar 12, 2015 4:24 pm

Typical mechanic - when you don't know anything about the vehicle start throwing parts at the noise.

The serpentine belt drives among other things:
1. the viscous heater serves absolutely no useful purpose except to provide a tiny bit of cabin heat a tiny bit sooner if you live in a really cold area. Frankly plugging the block heater in will do a whole lot more. The VH has a "clutched" pulley that is turned on/off (e.g. it's either engaged or not it does not cycle like the AC compressor) based on a message from the ECU based on coolant temperature. Those of us who live in not really cold areas just leave the viscous heater relay unplugged all the time.
2. the AC compressor which is also clutched AND operates in some vent modes, see owner's manual, even if the AC switch is not on. It cycles on/off to either cool the cabin or in certain vent modes with the heat on to reduce cabin humidity.
3. the alternator which has a decoupler pulley. If the decoupler pulley goes bad, not at all uncommon, you will get odd chirping sounds in the front often when the AC compressor cycles. Pop the plastic cap off the front of the alternator pulley and see if there is a lot of nasty red dust. Crank up the vehicle and look at the tensioner; is it bouncing or barely twitching. If red dust and/or bouncing the alternator pulley is shot. It can be replaced (idparts has it) or you can try to get a lifetime warranty alternator from like AutoZone.

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

I'm from Canada, it gets pretty chilly what part I'm in, and I read that the block heater kind of negates the need for the viscous heater on here. It's coming from the left side, when facing the front of the vehicle. Which leads me to believe it's not the alternator, I also have not seen any red dust anywhere. And none of the tensioners are jumping about. Is the viscous heater just a part inside that AC compressor? I couldn't find any reference material to see where the AC compressor is. I have the vent selector in off, and the chirping is gone. As soon as I put the temperature selector in any other place than full heat the chirping is on. Sorry for any inclarity.

thermorex · **Posted:** Thu Mar 12, 2015 7:08 pm

DeceitfulChicken wrote:

I'm from Canada, it gets pretty chilly what part I'm in, and I read that the block heater kind of negates the need for the viscous heater on here. It's coming from the left side, when facing the front of the vehicle. Which leads me to believe it's not the alternator, I also have not seen any red dust anywhere. And none of the tensioners are jumping about. Is the viscous heater just a part inside that AC compressor? I couldn't find any reference material to see where the AC compressor is. I have the vent selector in off, and the chirping is gone. As soon as I put the temperature selector in any other place than full heat the chirping is on. Sorry for any inclarity.

As you face the hood from front of the jeep, viscous heater is top left, ac bottom right of the engine.

geordi · **Posted:** Thu Mar 12, 2015 8:55 pm

Chirping from the belt is the alternator clutched pulley. If you don't replace the pulley, the failure will eventually cause the failure of the serpentine tensioner.

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

thermorex wrote:

DeceitfulChicken wrote:

I'm from Canada, it gets pretty chilly what part I'm in, and I read that the block heater kind of negates the need for the viscous heater on here. It's coming from the left side, when facing the front of the vehicle. Which leads me to believe it's not the alternator, I also have not seen any red dust anywhere. And none of the tensioners are jumping about. Is the viscous heater just a part inside that AC compressor? I couldn't find any reference material to see where the AC compressor is. I have the vent selector in off, and the chirping is gone. As soon as I put the temperature selector in any other place than full heat the chirping is on. Sorry for any inclarity.

As you face the hood from front of the jeep, viscous heater is top left, ac bottom right of the engine.

Using this information I turned the AC on max and the fan up and spent about 15 minutes trying to pinpoint the noise. It definitely seems louder in the right side facing the front. How do I go about fixing this? I'd there a clutch I can just replace or an I stuck replacing the whole compressor?

gumbygoose · **Posted:** Fri Mar 13, 2015 2:57 am

I'd replace the alt pulley. My crd only chirped when the a/c was on. I took the belt off and spun the pulley and it slightly wobbled. New alt pulley, no more sqeeky sqeeky.

gmctd · **Posted:** Fri Mar 13, 2015 3:48 am

I'll be the fourth (4rth) : alternator decoupler pulley..................

Even if it turns out to be one or more of the belt tensioners, the decoupler pulley begins signaling failure mode with melodious chirping - when chirping stops, the mechanism is locked up with resultant increased damaging effect on serpentine belt

flman · **Posted:** Fri Mar 13, 2015 8:54 am

AC on means more load on the charging system, running compressor clutch, blower and electric rad fans, and maybe even more pressure on the entire belt drive due to the increased load. I would change the alternator decoupler first.

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

Hey, thanks gents. I'll get on replacing that alternator pulley ASAP. I'll post back here with any updates.

geordi · **Posted:** Fri Mar 13, 2015 12:58 pm

Sorry if it seemed we all kinda dog-piled onto you there.

Good luck with the repair, it is fairly easy, especially if you have the special Metalnerd socket tool from IDparts. The pulley unscrews like any other nut or bolt, lefty-loosey, when you are holding the alternator shaft in a fixed position. The alternator shaft is a 10mm socket, the pulley is (IIRC) a 17mm hex.

DeceitfulChicken · **Joined:** Thu Mar 12, 2015 2:44 pm **Posts:** 6

papaindigo wrote:

Pop the plastic cap off the front of the alternator pulley and see if there is a lot of nasty red dust.

I'm not sure why I didn't do this before, but after class I took a flat headed screw driver and popped the cap off, sure enough:

I snapped that with my phone, that circular thing on the left is the cap and all the dust that came out on it. Sure looks like a decoupler pulley problem to me :-)r

geordi · **Posted:** Fri Mar 13, 2015 9:12 pm

<Mythbusters> Well, THERE's your problem! </mb>

beetlemn73 · **Posted:** Sun Apr 26, 2015 3:35 pm

I have chirping under the hood and I think ts the viscous heater bearing. Is there a way to change the pully bearing?

Let me add that the serp belt tensioner does seem to chatter abnormally at idle but then quiets out above. The chirping
also goes away above idle.

Thanks

Gary

WWDiesel · **Posted:** Sun Apr 26, 2015 10:17 pm

Check your alternator decoupler pulley, most likely cause of chirping. Many of us on this forum have been there and done that! Its a common problem with these Jeep CRD's.....
Read previous posts on this thread... :wink:

geordi · **Posted:** Mon Apr 27, 2015 4:33 pm

beetlemn73 wrote:

I have chirping under the hood and I think ts the viscous heater bearing. Is there a way to change the pully bearing?

Let me add that the serp belt tensioner does seem to chatter abnormally at idle but then quiets out above. The chirping
also goes away above idle.

Thanks

Gary

Read the entire thread again please. The solution is 100% this: Your alternator clutched pulley is failing. This is always the source of this chirping noise under the hood.

beetlemn73 · **Posted:** Mon Apr 27, 2015 6:01 pm

I have ordered a new Alternator pully to be installed this weekend. Thanks gentlemen.

ATXKJ · **Posted:** Mon Apr 27, 2015 8:44 pm

FYI - best way to replace it is a good 1/2" impact wrench with 17mm hex

even the factory tool has problems

this was a copy of the factory and he had problems too
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=75841

Chirping Under my Hood

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