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Discussion Starter #1
I have a Mark IV Jetta. Somewhere from the right rear or underneath the car is a dull knocking noise when driving over certain bumps on the road surface. It is not there constantly, only on certain road surfaces or when hitting certain bumps in the road.
I have checked the exhaust, replaced shocks and shock mountings, shock buffers as well as rear axle bushes. I have gone so far as to remove everything from the boot including spare wheel, as well as the rear parcel shelve/shelf. I have driven with rear seats locked in place and fold down. Noise persist. Someone tells me it might be the fuel tank but the tank is secured and tight.

Does anyone have an answer.

Brother Luv
 

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Probably the front sway bar bushings or sway bar links. The noise tends to travel around, check these first. The sway bar link bolts can go loose. The sway bar bushings should be tight. They get loose and there's a dull knocking.
 

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2nd check the front sway bar bushings and the links. This is a common problem and is more likely. The exhaust pipe could be rusted and causing a dull knocking - check the exhaust pipe and muffler mounts. The rear strut mounts could be bad but this is less likely than front clunking.
 

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Discussion Starter #4
Knocking noise right rear

Thanks a lot for response. Already replaced rear shock mounts. Noise still audible. Will inspect sway bar components. There is a slight knocking noise from front right but I wasn't sure that this noise could travel to the back of the car cause there is where you here it if you lie in the boot.
 

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Did you touch the front suspension recently? The sway bar's motion can loosen the front right sway bar link bolts. I suggest using locktite on them since their torque value is only 11 ft-lb. This lets the sway bar move without binding.

Chassis noise travels in strange ways. Even where you sit can make you think the noise is front vs. back since it bounces around - one person says the noise is coming from the left, the other person says it's coming from the rear. Since these cars tend to make noise from the front more than the rear, my guess is that the problem is from the front.
 

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Discussion Starter #6
I guess i might have concentrated so much at the rear suspension components that I must have overlooked the front. Will definitely check the sway bar and assosiated components.

Thanks once again. Your reply is much appreciated.
 

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Discussion Starter #9
Should both wheels be off the ground when you tight the sway bar bushes and end links or can you do one side at a time. Ive taken the right hand side wheel off and checked for loose sway bar bushes and end links but they feel secure.

Replies will be much appreciated.
 

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I think it's easier when both are in the air. You can't just shake it by hand, tighten the bolt to check. I believe that when one wheel is on the ground, the sway bar holds the other side tightly.
 

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IMHO, if the sway bar bushing has no gaps it's good, if there is a small space then it could be bad, if you can see a gap then it's bad. maybe the lower control arm bushings? loose control arm bolts or sway bar bolts?
 

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Discussion Starter #14
Rear Subframe bushes has been done two thousand kilometers ago. To me it sounds like the Exhaust or mufflerhitting something but I had it check several times at different Exhaust specialists. They say its fine.
Other times it sounds like the tank is hitting the underbody of the car but the noise is the same irrespective of the amount of fuel in the tank.

I haven't tried the dealers with this noise yet. Based on my experience with them I think it might just be a waste of money.
 

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Discussion Starter #15
Rear Suspension Noise

Noise is still there poeple. Must the sway bar end links be removed to check the condition of the bushings or can it be checked on the car? This noise is driving me crazy. When hitting certain sharp bumps in the road it sounds like a dull knocking sound from the rear, like the chassis or tank is hitting something. But whether the tank is full or empty the noise remains.
 

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The sway bar end links don't go bad often it's normally the sway bar bushings, are you sure the bolts are all attached? Maybe the subframe bolts loosened or something weird? Maybe a loose motor mount?
 

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No Luck Guys. Noise is still there. Replaced sway bar bushings and tighten end links.

Any other suggestions?

Most likely the noise is coming from the exhaust pipe just before the muffler, it hits the rear cross member, if you lift up your car, and check on the pipe bend going up over the rear axles, then straighten out just before the muffler, you will see on the bend that is rubbing against the cross member, if you see a metal scuffing, that is it, this only happens if you put wieght on the rear of the car, or you hit a bump. check it out and report back.
 

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Discussion Starter #18
Might have the cure

I went to MCarthy Volkswagen In Parow, South Africa and explained them about the noise from the rear suspension. They examined the suspension took the rear shock absorber apart, printed the different parts of the rear shock absorber from their computer and compared it to my unit. They discovered that part number 1H0 - 513 - 269D, which is called a "protective cap" was missing on both shocks(dampers). (I'm the second owner of this car.) This part slides over, like a little washer cover, over the little circlip near the top of the shock to prevent the circlip from opening. On examining the shock mounts they discovered that the circlip has worn a little recess in the shock mount from the bottom as well as in the shock mount pin itself. This recess/seating looks like it should be there because the circlip fits nicely into it. But the dealer assured me that the recess was due to the up and down bouncing and dampening of the car while on the move. Its impossible to fasten the shock properly without the protective circlip washer/cap.

Downside - not one dealer in South Africa has any stock.
Upside - The Volkswagen factory in Uitenhage, South Afica has stock and I have to wait two days for it. Two days expires tomorrow. Will put in and let you know.
 

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Discussion Starter #19
Wrong call Guys

The dealer and I got the parts mixed up. There is no washer around the circlip. I'v mistaken the black dust cover where the pin comes out of the shock for a circlip cover. So we are back to square one.

Final option: We have a company in South Africa called Fifth Avenue Motors which specializes and is highly regarded in suspension or other noises from automobiles. They ask a flat rate of R 672-00 ( 54 pounds or 90 dollars) to diagnose and fix the problem no matter how long it takes them to find the solution, a day or a week, stripping and reassemble anything included. You only pay extra if parts are needed. Only heard of these guys two days ago and been to them.

This seems my only option. Thanks a lot for your help guys. I'll also have a look at the advice of MACRPM.

Will let you know.
 

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That is an excellent option - $90 to fix a problem that has taken hours to solve is a good deal.

US spec cars do not use a circlip or washer on the rear shocks so I wouldn't know.

It's possible you have a defective shock mount or shock but those should be obvious when you remove them from the car.
 
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