My front has been rattling like crazy when I go over even the slightly imperfections in the road for a long time now, with the occasional Air Suspension Fault coming up. I finally got fed up with it and had my mechanic check it out. He diagnosed and replaced the lower control arm bushes. When I picked up the car, it drove beautifully! Except there was still the tiniest bit of rattling over really bad bumps, only noticeable if you're really looking out for it. Anyway, I took the car back to the mechanic for a different reason but told them about the tiny rattle still hanging around. They could hear the rattle on the test drive (which means I'm not crazy), but could not find the reason for it. Supposedly everything in the suspension in tip-top. They said the only thing it could possibly be is the actual air shock itself. Reading up on the forums here, I see a lot of evidence to support that theory. Well, this morning on the way to work, I notice the rattling is back, almost as bad as it was before, but not quite as harsh. Does this sound like an air shock issue?

 

Have you looked at the lower shock bush located in the wishbone ? Also the anti-roll bar bushes may be shot too. Then there are the upper wishbone bushes. BTW this latter part is very expensive, as bushes and balljoint are non-replaceable, however these are long-lived.

 

According to my mechanic, all the other bushes are good. Even if they were bad, how would that explain why the rattling was almost completely gone for an entire week?

 

Rattling struts is not just theory, they can fail inside and rattle and the only way

to prove it is to replace the struts AFIK.

 

I'm really starting to believe the struts are at fault. I'm just baffled by the fact that the rattling actually disappeared for a week after the bushes were replaced. If the struts are indeed the culprit, could the rattling come and go like that?

 

Seems unlikely.

If it was mine and I was really bothered by the noise I would buy an used strut and replace

it. Surpriosingly they can be changed quite quickly (?1.5 hours) as long as the T40 bolt at

the bottom comes off ok

 

The problem is that its not just noise. You can feel the rattling also. If it were just noise I'd probably be able to live with it. And I'd rather get new one from Arnott instead of getting a used one and risking the chance it'll fail soon as well.

 

Update: Last week, I replaced both front shocks with remanufactured Arnotts. While I was in there, I noticed that the rubber boots on the upper control arm ball joints were completely destroyed on both sides of the car. Since there was nothing I could do about it at the time, I put the new shocks in and ignored the ball joint issue for the moment. All the rattles went away and the car drives wonderfully again. I no longer feel as though I am tipping over on corners and bumps and dips in the road are negotiated well. Steering is also more responsive.

HOWEVER, after a week (just like last time after replacing lower control arm bushings), the rattling has returned. But this time it sounds more like a muffled knocking instead of the car-shuttering earthquake rattle it was before. And it only manifests itself when there's either a giant hole or bump, or at slower surface street speeds. At highway speeds, there is no noise or ride harshness (and believe me, the highways here in LA are just as bad as the surface streets). So far I have not noticed any degradation of ride quality, just the reappearance of the noise. If it stays like this, I could probably live with it, but if it gets too loud or if the ride quality is affected again, I will go nuts.

My question is: could the knocking noise be coming from those bad ball joints in the upper control arms? The noise is definitely coming from both sides, and as you may recall, both the left and right ball joint boots were wrecked. I'm going to try removing the old boots, cleaning up all the grease, oil and dirt, and replacing them with fresh new boots from a supplier I found in the UK. If that doesn't work, I guess I'll try replacing the entire arm, but I figure I'll try the easiest and cheapest fix first.

 

I'm having a similar issue but it seems to be coming from the rear of the transmission during moderate acceleration. So I had a four wheel alignment and had all four wheels balanced but that did not help. So far I've had the following checked to no avail:

-rear differential fluid
-u joints
-all suspension fittings
-driveshaft
-transmission and engine mounts

Please keep us up to date on this!

 

My knocking is definitely coming from the front wheel wells, no doubt about it. Funny thing is my mechanic checked the car out a few weeks ago and said that all the suspension components looked fine. How could they have missed the utterly destroyed rubber boots?

 

UPDATE: I sourced some rubber boots online to replace the ripped up ones in the upper ball joints. First, I removed the remnants of the old boot, cleaned out the joint with WD40 until there was no more old grease left, slathered on a thick coating of new grease, and then fit the new rubber over it. After I reconnected the wheel knuckle to the upper arm, I used zip ties to tighten the top and bottom seals of the boot. I then noticed that my driver side tie rod end had a ruptured boot as well, so I replaced that, and bolted everything back together. HOWEVER, when I was tightening the sway bar links, the ball joint bolt holding it to the sway bar sheared in half

So the Jag is out of commission until my new sway bar links arrive. That was going to be my next plan of attack in case the clunking returned, so I guess I'll be killing two birds with one stone. I don't know how well the repaired ball joint boots will hold up, but I figured it was worth a shot. Worst case is I'll have to replace the entire arm.

Tonight I'll be tackling the air compressor rebuild using Bagpipingandy's kit.

 

UPDATE: I repaired the compressor using Bagpipingandy's kit...and the ASF message continues to rear its ugly head. I would be able to live with it if the ride didn't become so harsh whenever the message appears. I don't know what my next step should be. There doesn't seem to be any difference in height at all. I'm stumped. I've decided that if I continue to have cold weather problems like last year, I'm going to go with the coilover conversion and be done with it.

I replaced both sway bar end links. Unfortunately, the damned knocking noises are still there. I'm thinking my next move will be to replace the entire upper control arms.

Any tips, thoughts, suggestions would be appreciated. I'm quite discouraged at the moment.

 

Ok, try the following. After starting the car wait 2-5 minutes before driving off. Do you get the ASF message now?

Guus

 

Xag, I saw that tip on the other thread. I'll be trying that out tonight on my way home. I may have to try it several times though, because the ASF message doesn't necessarily come on every drive cycle. Maybe once every other cycle, and only after a few minutes of driving.

 

I don't know if I mentioned it before, but the suspension knocking noise can usually be felt through the brake and gas pedals. Anybody have a clue?

 

I don't want to send you off in the wrong direction but this might help.

People on here have had problems with noise from the ARB (sway bar)

bushes and I have an idea that if you disconnect the ends of the ARB and

drive around like that (for a short while) you may notice an improvement in the noise if

that is the source.

I know that the fitting holding the ARB is not easy to get to in order to check

for tightness.

Search this forum for details on noise emanating from the ARB.

Remember this is from someone who has never replaced a bush or had a rattle

in 6 years of ownership! (touch wood).

 

I actually do recall reading that, however I'm reluctant to drive like that for any amount of time because the streets in my neighborhood are always extremely busy with crazy drivers and pesky pedestrians, so I'm afraid that if I have to suddenly avoid something, my steering capabilities might let me down and I'll have to worry about something much larger than a knocking suspension.

 

I tried that last night on the way home, and the ASF message came on after 10 minutes. I tried it again this morning, ASF message came on after 10 minutes. Before I did the piston ring repair, I only used to get the ASF once in a while. Now I get it every single time I drive, but only after 10 minutes. There has been no difference in ride height, but the ride quality does seem harsher. I'm wondering if the compressor has just had it, and needs to be completely replaced. I'm disappointed now, but I know how upset I'll be if the ASF remains after I install a brand new unit.

After re-reading your quote, I must admit that I only let it sit for 2 minutes. Perhaps I should try 5?

 

Well, I tried waiting 5 minutes, and still the damn ASF message comes on after 10 minutes of driving. Every single time now, like clockwork. I should've left the compressor alone and not attempted the piston rebuild. The ride quality is rock hard now, feels like my girlfriend's Infiniti G37S. But there still isn't any difference in height. And I haven't heard the compressor come on at all since I did the repair. After reconnecting the battery and starting the car on Saturday after the rebuild, the compressor came on and quickly refilled the front shocks, but nothing since then. I'm stumped. Someone must have a solution.

 

Actually this is strange. If the air suspension looses pressure the car gets softer and rolls more. I got both front shocks replaced today and the car feels a lot tighter now.

To test if it's not the CATS acting up you could remove both electrical connectors from the front shocks. This forces the dampers to stiff. You could compare if that is what you get when the ASF appears.

Of course something could have gone wrong when rebuilding the compressor but you can always try to fix it again. First check if it runs at all. Try listening a few mornings after you start the car if it starts and stops with the vent valve letting air out. Listen at the front left wheel for it.

Guus