Rattling noise at idle

remwines · **Posted:** Wed Dec 24, 2014 3:26 pm

Our '05 CRD has developed a rattling noise around the engine that I can not locate. The rattle sounds something like a small wheel with loose lug nuts and it only occurs at idle. As soon as I give it a little throttle, the noise goes away. I've used a stethoscope probe to check all of the obvious stuff, anything from the accessory drive, timing belt cover and so on, but couldn't find it. Wife even took it to the local Jeep dealership and they are clueless. Being in California, they don't see many CRD's. I replaced the timing belt and related parts with quality components about 25K miles ago and suspected something there may have failed. But nothing was noticeable from the stethoscope on the cover. All systems are working fine, there are no changes in performance and the transmission seems normal. Any suggestions?

Thanks!

Bob

toby · **Posted:** Wed Dec 24, 2014 10:33 pm

Bad motor mount? I cut one open that was rattling and they are filled with fluid and have a disc bolted inside that came loose and rattled. The fluid and disc act as a shock absorber for the vibration.

flman · **Posted:** Wed Dec 24, 2014 10:48 pm

X2 on the mounts, sounds like nuts being ground.

CATCRD · **Posted:** Thu Dec 25, 2014 4:10 pm

If the noise goes away above idle speed, I bet it's the alternator decoupler pulley seized up.

geordi · **Posted:** Thu Dec 25, 2014 4:36 pm

Interesting... Could be another one with the transmission mount too. There is a rubber mount between the transmission and the crossmember, it could be causing a sound there if the transmission is hitting the member "just right" on yours. Mine did it at low speeds, and went away above that.

Jack the transmission a little bit and shove a rubber pad or something in there to pad it, and see if anything changes.

remwines · **Posted:** Fri Dec 26, 2014 5:11 pm

Thanks for the input guys. A friend brought his CRD by today and with both vehicles running side by side, I could feel (and hear) that my engine vibration was being transmitted into the chassis much more than his. So, at a minimum, it needs new engine mounts. Question: are the mounts the same part number for L&R, and who is a good vendor to buy from. I would like to support the people who support us.

To CATCRD, I checked the alternator with a stethoscope and found no unusual noises, nor any rust powder around the de-coupler. I have a similar alternator on a Jetta TDI that completely failed last month and fell off. As you might imagine, that de-coupler assembly was covered with rust dust. But if it does turn out to be the de-coupler on the Jeep, it will be easy to change out. On the Jetta, I had to put in about 6 hours of work to R&R that alternator.

Thanks!

Bob

flman · **Posted:** Fri Dec 26, 2014 7:19 pm

Buy from IDparts.com

The right side has a heat sheild, some just buy 2 lefts and move the heat shield from old to new. I did this one time and next time I will buy a left and right instead of screwing around with an old heat shield, but looking at the price difference maybe not?

http://www.idparts.com/catalog/index.php?cPath=29_57

thermorex · **Posted:** Fri Dec 26, 2014 8:19 pm

flman wrote:

Buy from IDparts.com

The right side has a heat sheild, some just buy 2 lefts and move the heat shield from old to new. I did this one time and next time I will buy a left and right instead of screwing around with an old heat shield, but looking at the price difference maybe not?

http://www.idparts.com/catalog/index.php?cPath=29_57

+1 for getting left and right and not 2 lefts. It was quite annoying for me to move the shield from old mount but maybe I just wasn't lucky and the shield hole was mushed and deformed a bit in the old mount. For 10-20 bucks extra difference, I'd get left and right.

usa591 · **Posted:** Sat Dec 27, 2014 5:07 pm

From personal experience, rule out the engine mounts first: when mine were bad, it sounded like loose change rattling around inside a tennis ball.

Secondly, it could be the front driveshaft. I had this rattling sound at idle that was driving me crazy--sounded like a loose washer or loose change--that seemed to be coming from the bottom of the engine block & I could never pin-point it. Well, a few days ago I was underneath the CRD while it was running and by chance I grasped the front driveshaft…and the noise stopped! Sure enough, there's just enough play in it that when the vehicle is idling, it vibrates and sounds like a loose change/washer rattling. Not bad, but just enough to drive me crazy.

I would love to find another CRD around here in Los Angeles to compare mine too, but the play is so minimal that I think I'm ok.

Anyway, hope it helps.

WWDiesel · **Posted:** Sat Dec 27, 2014 8:15 pm

usa591 wrote:

From personal experience, rule out the engine mounts first: when mine were bad, it sounded like loose change rattling around inside a tennis ball.
Secondly, it could be the front driveshaft. I had this rattling sound at idle that was driving me crazy--sounded like a loose washer or loose change--that seemed to be coming from the bottom of the engine block & I could never pin-point it. Well, a few days ago I was underneath the CRD while it was running and by chance I grasped the front driveshaft…and the noise stopped! Sure enough, there's just enough play in it that when the vehicle is idling, it vibrates and sounds like a loose change/washer rattling. Not bad, but just enough to drive me crazy.
I would love to find another CRD around here in Los Angeles to compare mine too, but the play is so minimal that I think I'm ok.
Anyway, hope it helps.

If the front driveshaft is rattling; are the CV joints dry and contain no grease? A properly packed with grease CV joint should never rattle!!!! :shock:

thermorex · **Posted:** Sun Dec 28, 2014 12:47 am

WWDiesel wrote:

usa591 wrote:

From personal experience, rule out the engine mounts first: when mine were bad, it sounded like loose change rattling around inside a tennis ball.
Secondly, it could be the front driveshaft. I had this rattling sound at idle that was driving me crazy--sounded like a loose washer or loose change--that seemed to be coming from the bottom of the engine block & I could never pin-point it. Well, a few days ago I was underneath the CRD while it was running and by chance I grasped the front driveshaft…and the noise stopped! Sure enough, there's just enough play in it that when the vehicle is idling, it vibrates and sounds like a loose change/washer rattling. Not bad, but just enough to drive me crazy.
I would love to find another CRD around here in Los Angeles to compare mine too, but the play is so minimal that I think I'm ok.
Anyway, hope it helps.

If the front driveshaft is rattling; are the CV joints dry and contain no grease? A properly packed with grease CV joint should never rattle!!!! :shock:

+1. A bad cv joint would rattle, even lubed, if it had been used after an extended period of being ran w/o a rubber booth or with a proper "one piece" rubber booth (read broken rubber booth).

geordi · **Posted:** Sun Dec 28, 2014 2:06 am

The CV joint is between the wheel and the front differential pumpkin. That has nothing to do with the front driveshaft, or prop shaft. If that is loose, it is the universal joints that are buggered usually.

usa591 · **Posted:** Sun Dec 28, 2014 2:12 am

WWDiesel wrote:

If the front driveshaft is rattling; are the CV joints dry and contain no grease? A properly packed with grease CV joint should never rattle!!!! :shock:

The CV joint covers seem to be intact, don't know how lubricated they are under the cover.

Here's some audio of what I'm hearing:
http://piersonjacquelin.com/permalink/C ... tNoise.mp4

You'll definitely hear the higher, tinny rattle and then I grab the driveshaft and it's muted. I grabbed it and tried to jerk it around pretty good and it seemed pretty solid.

WWDiesel · **Posted:** Sun Dec 28, 2014 1:34 pm

geordi wrote:

The CV joint is between the wheel and the front differential pumpkin. That has nothing to do with the front driveshaft, or prop shaft. If that is loose, it is the universal joints that are buggered usually.

I was speaking of the front driveshaft or prop shaft which does have CV joints & boots on each end of it; not the front axle shafts between the wheels and differential!
I had to replace a CV joint & boot on the front driveshaft at the transfer case end as it had a busted boot and all the grease had slung out and the joint was very dry, full of grit, and rattling... :roll:

geordi · **Posted:** Sun Dec 28, 2014 4:42 pm

Huh, interesting.

Its been a while, so my memory could be fuzzy, but I don't remember my prop shafts having boots on them covering a CV, just ordinary exposed universals.

I wish there was an easy way to re-boot those things and pack them with grease, but once the boot is torn, you might as well just recycle the thing and replace it.

WWDiesel · **Posted:** Sun Dec 28, 2014 8:46 pm

geordi wrote:

Huh, interesting.

Its been a while, so my memory could be fuzzy, but I don't remember my prop shafts having boots on them covering a CV, just ordinary exposed universals.

I wish there was an easy way to re-boot those things and pack them with grease, but once the boot is torn, you might as well just recycle the thing and replace it.

Yep, you fuzzy, the front prop shaft has CV joints on each end with inner boots, the rear driveshaft has the normal exposed U-Joints.... :ROTFL:

One of the joints:

geordi · **Posted:** Sun Dec 28, 2014 9:16 pm

Yeah, OK, I remember that look now - Mine was ripped, but I think I mis-remembered it b/c I'm used to the external boot styles of normal CVs.

ATXKJ · **Posted:** Mon Dec 29, 2014 5:02 pm

FYI - one of the notes on Motor mounts -

the noise will change while sitting still idling in Neutral/Drive/Reverse

you can change back and forth and hear it.

flman · **Posted:** Mon Dec 29, 2014 5:40 pm

geordi wrote:

Huh, interesting.

Its been a while, so my memory could be fuzzy, but I don't remember my prop shafts having boots on them covering a CV, just ordinary exposed universals.

I wish there was an easy way to re-boot those things and pack them with grease, but once the boot is torn, you might as well just recycle the thing and replace it.

You used to be able to buy a split boot for the old rear engine VWs? No one makes these any more?

remwines · **Posted:** Wed Jan 28, 2015 10:31 pm

Update: I replaced both engine mounts today and unfortunately, it still rattles. I have a car lift which makes working on it a lot easier. The engine skid plate was left off when I started it and I raised it back up with the engine running. The rattle seen loudest in the area of the harmonic dampener. The dampener pulley and other pulleys in that area were not wobbling. With the engine off, I checked for play and they are all secure. It's got me baffled. The rattle does go away when the RPMs are over 1200. I wonder if it is something in the timing belt assembly. I replaced everything in the assemble with quality parts about 40,000 miles ago.

FYI, I bought both OEM engine mounts from Avondale Wholesale Parts (Avondale Dodge, Chrysler, Jeep in the Phoenix area) and the price seemed very reasonable. The mounts were a little more than $38. each and that included shipping. They are who I generally get my Dodge and Jeep parts from.

Rattling noise at idle

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