mystery engine squeal..

dr5chrome · **Posted:** Sat Jan 24, 2015 12:13 am

Well - ive almost got all the kinks out after this purchase - There is just one mystery noise left to solve.

The shop that did the belt service I found out, did not change any of the rollers associated with this service.
With that in mind, I have an intermittent 'squeal' coming from the engine. In my gas-engine experience, it sounds like a belt squeal, but could be a chuddering spinning bearing. I still don’t know this engine too well, so I am actively learning it – as far as I know, the only things that spin on the engine are the 2 belts and the turbo… maybe the fan-clutch.. it is definitely somewhere in these components, but I might be wrong. It can occur when I am driving along, taking my foot off the peddle suddenly [no breaking], then down on the peddle to accelerate again “squeal” – or it can squeal if I am on the freeway and suddenly take my foot off the gas.. It is not consistent. It will choose when it occurs. I cant make it happen on demand.

Unfortunately, I still cant eliminate the timing-belt rollers..

Anyone have the experience??

thanks again.. dw

2005 CRD 2.8

thermorex · **Posted:** Sat Jan 24, 2015 1:04 am

Get a mechanical stethoscope and try isolating the noise. Take out serpentine belt and see if you can hear it.

dirtmover · **Posted:** Sat Jan 24, 2015 11:41 am

Do you hear a continuous squeal or chirp? Belt squeal is associated with slippage. The idlers and tensioner under the timing cover don't present enough resistance to cause slip. I wouldn't worry too much about them immediately. I'd focus on the accessory belt first as a likely culprit. If it wasn't changed at your recent service it's probably due and also the tensioner. The bearings in my accessory tensioner and idler were both shot after 100K.

WWDiesel · **Posted:** Sat Jan 24, 2015 12:04 pm

Could be the override clutch on the alternator! They are known for going bad. Look at the pulley for any signs of red dust. (rust) :idea:

dr5chrome · **Posted:** Sat Jan 24, 2015 1:55 pm

thanks for the replies..
I spent the entire morning trying to find a consistent method of having this engine squeal come up. I believe I have it. While driving [at any speed], if I take my foot off the gas, quickly w/no brake, letting the engine RPM go as low as it will go, then hitting the gas back up to where it was, I get the squeal almost 90% of the time.. Gradual pedal, it will not squeal..

Getting it to do it consistently has made it hard to determine where it is coming from. Im almost sure it's something spinning. The sound is a cross between a squeal & chirp, but not quite as high as very loos belt - or as loud as a power steering belt slip you hear on other cars now and again..

dw

papaindigo · **Posted:** Sat Jan 24, 2015 2:32 pm

If you do the same "throttle" thing will not actually driving will it chirp? If so remove serp belt and repeat. If no chirp it's a serp belt thing.

I suspect alternator decoupler pulley. At idle, with flashlight if needed, from adjacent to left front wheel look down serp belt from alternator pulley (remove plastic engine cover) to serp belt tensioner. Is it dancing or barely twitching. If dancing it's likely the decoupler pulley is shot.

dirtmover · **Posted:** Sat Jan 24, 2015 2:50 pm

Here, look at this

https://www.youtube.com/watch?v=hrFcPqZuO3A

dr5chrome · **Posted:** Sun Jan 25, 2015 1:00 am

pap, dirt - wow.. I think you have it!

YES! the serp belt tensioner "is" dancing.
I haven't tried to rev the engine with the hood up. I only hear the noise while I am driving.
..but I have no idea what is normal for this engine.
here is a vid of the 'dance'; https://www.youtube.com/watch?v=21zxJMr ... e=youtu.be

What should be replaced? just the decoupler? Is this 'dance' showing something to be bad?

If this is indication of it being bad, why on earth did they not see this upon changing the belts.. :banghead:

regards..dw

papaindigo · **Posted:** Sun Jan 25, 2015 10:08 am

That's not a "huge" amount of motion but I just went out and looked at mine at idle and mine essentially doesn't move at all.

There are 3 "clutched" things involved with the serp belt. Try this:
1. pull relay R36 in the power distribution center (black rectangular box in front of battery - it's a bit finicky to open/close) to disable viscous heater. Does twitch go away? If not replace relay.
2. turn your AC vent control knob (center one) to "O" to disable the AC compressor. Does the twitch go away? If not put control knob back where it was.

If neither of the above make the twitch go away check the alternator decoupler per the video dirtmover posted or just pop the plastic cover and see if there is a fair amount of red dust.

If the alternator clutch is bad you can just replace the clutch. See http://idparts.com/catalog/index.php?cPath=123_129 . Removal can be somewhat difficult; see viewtopic.php?f=5&t=75841&p=796353&hilit=alternator#p796353 for a DIY tool or you can get the Lisle LS57650 tool kit for about $30-35 for a parts store or idparts. Alternatively you might be able to score a lifetime warranty replacement alternator with pulley for ca. $150 at AutoZone or some such.

The dance can be bad as it will eventually destroy the tensioner and there has been one report where a jammed serp belt caused an engine to jump time.

Why they did not notice I have no clue.

dr5chrome · **Posted:** Sun Jan 25, 2015 5:56 pm

OK ... why a supposed expert shop would miss such a thing is beyond me..

pap - maybe you should call them and offer tech lessons :rockon:

http://www.dr5.com/altpuly1.jpg
http://www.dr5.com/altpuly1b.jpg

I did the AC thing 1st, no change to the belt dance.

this rust you mentioned is a clear sign where my noise is coming from.

Hats off to 'lostjeeps' !

best regards, dw

papaindigo · **Posted:** Sun Jan 25, 2015 6:01 pm

Yep that's it. Time for a new decoupler or new alternator.

CATCRD · **Posted:** Sun Jan 25, 2015 10:56 pm

dr5chrome wrote:

While driving [at any speed], if I take my foot off the gas, quickly w/no brake, letting the engine RPM go as low as it will go, then hitting the gas back up to where it was, I get the squeal almost 90% of the time.. Gradual pedal, it will not squeal..

This sounds like a boost leak to me. When you roll on to the pedal gradually boost does not climb very high and you don't get the leak. Check/reseat/retighten your intercooler hose connections. Make sure they are squarely installed and clamp sits behind the lip of the opening.

devilkin4 · **Posted:** Sun Jan 25, 2015 11:21 pm

tonight my crd has started to squeal on idle and shut down. its not very loud but its there ill have to check it out tomorrow, but watching the video it sounds like the decoupler as well am i wrong in assuming that?

dr5chrome · **Posted:** Tue Jan 27, 2015 4:49 pm

catcrd - If it were a turbo leak, I think it might be consistant. Since the serp belt was changed it is less consistent, which makes sense - It is something on the serp belt - when I discovered where pap suggested to look [tensioner dancing], then tried the relay removal, still had the dance. Upon removing the decoupler cap there was the 'red/rust/dust', which indicated this part was bad. but i will look also where you suggested.. thanks again! dw

CATCRD wrote:

dr5chrome wrote:

While driving [at any speed], if I take my foot off the gas, quickly w/no brake, letting the engine RPM go as low as it will go, then hitting the gas back up to where it was, I get the squeal almost 90% of the time.. Gradual pedal, it will not squeal..

This sounds like a boost leak to me. When you roll on to the pedal gradually boost does not climb very high and you don't get the leak. Check/reseat/retighten your intercooler hose connections. Make sure they are squarely installed and clamp sits behind the lip of the opening.

CATCRD · **Posted:** Tue Jan 27, 2015 11:47 pm

Boost is not consistent, so the sound of a leak won't be either. At low pressures it doesn't leak, or does inaudibly. At moderate pressures you hear it, and at higher pressures the frequency can be above human hearing. The alternator decoupler sound is usually a fast chirpchirpchirpchirp sound, not a squeal.

dr5chrome · **Posted:** Thu Jan 29, 2015 12:11 am

so now i'm confused...

We just got done getting all that needed to be done. Along with changing out the timingbelt rollers - that were not done the 1st time - ALL the serp belt rollers including the decoupler and tensioners.. I thought for sure one of these was causing my intermittent squeal/chudder as described..

..no such luck. I guess ill have to wait until something falls off.
CAT*** had all the hoses and connections checked. Nothing is broken or leaking..

..anyone with any other ideas for possible cause?

dw

glaspak845 · **Posted:** Sun Feb 15, 2015 7:58 pm

I just had a mysterious squeal which I thought was a belt turned out to be the alternator. Squeal went away when the engine was reved up. The remanufactured alternator fixed squeal.

mystery engine squeal..

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