Idle Vibrations

2000 XJ Sport, 4x4, I6-4.0, AW4, NP231, D30/F, 8.25/R
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<font color="#666666">Vibrates when idling (or under 1000rpm, in P or N)</font> I can hear/feel the vibration a little more when: my brakes are applied in D or R gears- Here's what I can tell ya: Not enough to shake the mirrors, all the gauges read ok, pretty sure I need new rear brake shoes and adjustment-it's not bad. I bought the XJ about 3 months ago with 85,670mi-I have replaced the battery, and spark plugs (Champion 4412). Tensior pulley is good, motor & tranny mounts are good- not positive about my u-joints.. I run 87, tried 89,nothin.. It's been sounding more like a diesel lately.. ? Thought it mighty be dirty injectors so, I put a bottle of Techron in with a tank of gas the other day, I noticed smoother throttle ... still vibrating and b.s. ...

<font color="#666666">Now for the noise:</font>
It makes a weird 'tick/tack'/diesel engine/starter turning over when then engine is running/loose nut, or bearing (I'm pretty sure it's not)-kinda noise [img]/ubbthreads/images/graemlins/tongue.gif[/img] (best I can describe it). Coming from Bellhousing area..It happens between idle and 1500RPMs, basically when I tap the gas pedal to bring up the RPMs-it's not constant, or in a pattern, kinda random(goes along with loose nut or bearing sound)


...I changed the battery and Trans Fluid (4qt service)/filter 2 days after owning it, nothing out of the norm the magnet. Motor/Trans mounts, good-Transfer Case and Diffs are good, changed spark plugs(Champion4412), Rear Main is leakin, need to replace Oil Filter housing's gaskets. I tightened every damn bolt, with every size in my socket set!-front to back, nothing was loose, I basically got every freakin bolt under the XJ... the vibration is more noticable in cold weather (only mornings, Cali ) could this simply be my IAC goin bad? (hopefully, cheap fix)

So far, I've been told to inspect/repair: the Harmonic Balancer, might be cracked or somthin, Trans-to-Engine bolts, Flexplate in bellhousing, Pulleys: loosen the belt to see if a pulley confesses, tighten or replace.

[img]/ubbthreads/images/graemlins/thud.gif[/img]

Thanks if you've read all this [img]/ubbthreads/images/graemlins/bs.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img] .. I really appreciate anyones questions, comments, or advice!

[stump_breaker]

I would check

Engine mounts
Transmission mount
torque converter bolts
dead cat in fan belt [img]/ubbthreads/images/graemlins/grin.gif[/img]

You're sure they are good? They can be deceiving. Are they rubber or have you upgraded to the poly ones? The poly ones send out a lot of vibration.

[the_fixer]

Vibrations; Motor mounts
Champion spark plugs; "Mama didnt raise no fool"
Gasoline; Low Octane is good, Its an XJ, not a GTO
Sounds like a Diesel; Piston Slap--do a 'search' on the subject.
Smoother Throttle; Clean up your TBI
[img]/ubbthreads/images/graemlins/givemebeer.gif[/img] Yes I am drunk, I do my best work when Im drinkin.

[optdoug]

Check the bolts that hold the flywheel in place. This happend to my jeep about a year ago. I thought it was a bearing or something and thought that I was in for a major repair.
It turned out to be the bolts holding the flywheel and is was making a funky clicking sound at idle. Once i started moving, the flywheel would start to spin fast enough that the noise went away.
The good news was that I didn't even have to remove the tranny to tighten the bolts!!!

Motor Mounts and Trans are rubber (O.E.), I've checked em a couple times, no cracks or bad wear, even used a mechanics mirror. I've read about piston slap, don't think that's the case. I'm gonna loosen the belt to see if any pulleys confess, and then I'll tighten the flex plate: there's like 4 bolts holding a dust shield to bottom face of the bellhousing-I have to remove? Then I can get to it right? Is there a torque spec? If my buddy is around, I can borrow some tools from him, I wanna jack up the rear, check the drums/brake parts. I also have a "tsshhh" sound coming from passenger side, sounds like front bearings goin bad/rear brakes. Almost as if a Librarian is clinched to the bottom of my XJ shushing me!

Keep ya updated [img]/ubbthreads/images/graemlins/thumbsup.gif[/img]

[optdoug]

You will have to remove the inspection plate under the tranny. Then you can get to the bolts. I am not sure what the torque specs are, but i would guess somewhere between 20 and 40 ft lbs.

As far as the tsshhh sound goes, it sounds like maybe your brakes are metal to metal. Take the wheels off and take a look. Usually when its a bearing problem, it is more of a grinding sound like Grrrrrrrrrr [img]/ubbthreads/images/graemlins/grin.gif[/img]

[Kevlar]

Probably not even related, but I notice a rattle in my 01 that seems to come from the T-case, happens the same times yours does (in drive, brakes applied, more noticeable in the mornings when cool, etc.). When I "jiggle the handle (4 wheel shifter)" it goes away temporarily. I know, I might as well fix it by turning up the stereo, but it's been doing it for about 3 years with no issues. Maybe I should be more worried?

[NIX]

I have a Tsssshh sound from the paasenger side, but I think it's the vacuum that operates the heater valves...

[the_fixer]

I had a Girrrrgle sound coming from my seatbelt, it is was just my stomach.

This was a lil odd.. went to loosen the belt, put the wrench on the Idler Pulley nut (15mm), figuring I'm gonna hafta use some elbow grease to loosen this sucker (heard of others using breaker bars), start to loosen and just gives.. there was hardly any resistance. Is there a torque # on the Idler Pulley and/or tensioner bolt?

So, having the Idler Pulley nut on 'hand tight' made my mind slip the whole idea of loosening the belt to see if a pulley is loose, or bad bearing etc. Tightened that sucker and the tensioner bolt.. took it for a quick ride around the block, vibes are less but, still more noticable when XJ is stopped, with brakes applied in R or D.

Is there any actual 'Tests' I can perform on the MAP, IAC other sensors? I'm almost ready to purchase new sensors, motor/trans mounts...

No Check-Engine-Light.. I think I'll try and stop by a gas/smog station, or Autozone or somebody that can scan my XJ.

...my 4.0 still thinks it's a Diesel.. Oil Change is comin up, I'll probably put somthin thru it before I put fresh oil in.