Strange sound coming from front passenger side strut

Strange Noise a Bad Upper Strut Mount Can Make - YouTube

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www.youtube.com/watch?v=khZ16AOztT4
Jul 25, 2012 - Uploaded by MudRFunR Front Strut & Steering Noise - Does Your Malibu Sound Like This? 08 Malibu used in this video.

could be loose strut springs , strut shocky mount , top strut bearing, loose wheel bearings, suspension mounts.
have it inspected by an accredited suspension shop.

The struts model (MacPherson Strut),are both in front and back of this car.
2000 - 2006 Hyundai Elantra Shock Absorber and Strut Assembly - Rear, Driver Side, KYB GR-2/EXCEL-G, Twin tube, Strut Assembly. $72
2000 - 2006 Hyundai Elantra Shock Absorber and Strut Assembly - Rear, Passenger Side, KYB GR-2/EXCEL-G, Twin tube, Strut Assembly $68
1996 - 2006 Hyundai Elantra Shock Absorber and Strut Assembly - Front, Driver Side, KYB GR-2/EXCEL-G, Twin tube, Strut Assembly $67
1996 - 2006 Hyundai Elantra Shock Absorber and Strut Assembly - Front, Passenger Side, KYB GR-2/EXCEL-G, Twin tube, Strut Assembly $63
Of course this is only the cartridge, you have to transfer the spring, and the top mount of the existing strut. You need a pair of coil spring compressor to do the job. The basic procedure to replace a strut is:
Remove the top nuts that secure the strut assembly to the frame mount inside the engine compartment. Do not remove the center nut.
Mark the lower strut mounting location on the hub for installation reference. The alignment will be close if the new strut is installed in the same position.
Remove the bolts that hold the strut assembly to the hub.
Remove the strut assembly from the vehicle.
Mark the top mount for installation reference. Using a side mounted spring compressor, compress the spring and remove the top nut and retaining washer. Pull strut assembly out from the bottom of spring.
Slide the new strut assembly up into the spring and reposition the top mount onto the spring in the same position that it was removed. Install the retaining washer and top nut.
Tighten the top nut to the manufacturer's specifications and carefully remove the spring compressor.
Place the strut assembly back into the vehicle.

It has springs around the struts above the tires. Sounds like you have a bad strut plate bearing.

See if you can bounce car and replicate the noise. If you can, you should be able to find it, and put your hand on it. Stabilizer bushing are a place to look, both at the lower a arm and on the frame. If you narrow it down to the strut, it will need to be replaced. The front trans mount also goes bad, try putting it in drive with your foot on the brake and give it some gas and see if the engine moves an excessive amount.

Ford has a technical service bulletin out on this vehicle that may help solve your problem. The number is 04-6-1.
Here is the info:

ISSUE: Some 2000-2004 Focus vehicles may exhibit a front end creaking, crunching, grinding and/or rattling noise from the front suspension while driving at slow speeds, over bumps, and/or while turning.
ACTION: Noise, vibration, harness (NVH) conditions may originate from many areas. A thorough inspection of the front suspension is necessary to determine the cause. To service, refer to the following Service Procedure and inspect the suggested areas first.
SERVICE PROCEDURE

1. Inspect front strut fasteners and confirm that they are tightened to the correct torque.
   1. Front strut to front knuckle, (one (1) driver / one (1) passenger), 90 N-m (67 lb-ft).
   2. Front strut mount to body, (three (3) driver / three (3) passenger), 30 N-m (22 lb-ft).
   3. Front strut rod to strut mount, (one (1) driver / one (1) passenger), 66 N-m (49 lb-ft). NOTE: MEASUREMENT OF TORQUE MUST BE DONE IN THE TIGHTENING DIRECTION. NOTE: IN ORDER TO APPLY THE PROPER TORQUE TO THE FRONT STRUT ROD TO STRUT MOUNT FASTENER, A HEX KEY WILL BE REQUIRED TO HOLD THE STRUT ROD IN PLACE WHILE TIGHTENING THE NUT.
      
2. Inspect for loose stabilizer bar end links.
   1. Firmly grasp the links and shake them - both along the direction of the link and transverse to the link orientation in the inboard/outboard vehicle direction. If looseness is felt continue on to Step 2b, if no looseness is felt continue on to Step 3.
   2. Inspect the link end joints. If they do not appear severely corroded, torque the nuts (use anti-rotation feature to prevent ball joint damage) to 50 N-m (36 lb-ft), and repeat Step 2a. If links still feel loose after tightening or if the joint shows evidence of severe corrosion, replace the link (YS4Z-5K484-AA).
3. Inspect for the top spring sleeve coming out of position. This may cause a squeaking noise between the sleeve and indent on the ridge of the upper spring seat, or it may cause a clicking noise between the spring and upper spring seat if the sleeve is completely out of position. If the sleeve is out of position continue on to Step 3a, if the sleeve is positioned properly continue on to Step 4.
   1. Install a new rubber sleeve (1S4Z-8484-AA). Install the new rubber sleeve starting from the top of the spring coil where it contacts the spring plate.
4. If the noise is a clicking or popping from the front strut, install a service spring end cap (4S4Z-5L302-AA) on to the top spring tip. Reassemble and reinstall strut per the Workshop Manual Section 204-01.

Check the macpherson struts to ensure they are not loose.  One way to check is visually in the engine compartment.  Check the top of the struts to ensure the nuts are not loose.  Another is to raise the side of the van where you hear the clunk.  Raise it so the wheel is off the ground.  Grasp and shake the strut to see if it is loose.  The struts should not be loose, but you never know.  As the strut is certainly ivnolved in bumps and rotates when the wheel turns, I would check there since you have already explored the bushings and links.

the car is aging

there are other bushings and ball joints to make noises at that speed

the top rubber mounts failed for a reason

if i were on that job i would have replaced both gas struts
at the same time....

not much structure to the top strut mounts
see pictures in link
Strut Mount Early Small Chassis Audi Density Line

Sounds like the front shocks/struts are too weak to support the vehicle. Stand at drivers front of vehicle and push down very hard watch as vehicle rebounds and bounces until it settles, then try the same on passenger side. Good shocks/struts allow a bounce or so, but will appear firm not loose.keep me posted to your results.

Year, make, model, engine and if it’s a 4x4 should would help