Clunking noises after Strut replacement

How many miles on the odometer?

Did your friend replace the top strut mount on both sides? That is a wear part because it has to pivot as the front suspension moves up and down.

Who is the manufacturer of the replacement struts?

Does your friend have an opinion about what is loose? If not, I suggest you check the front sway bar rubber bushings which may be worn.

 

The OEM is KYB, which is a good brand.

If the noise is getting worse, not better, that is certainly not reassuring. Probably a good idea to have your local dealer check out the front suspension to see what the problem is.

 

I have $5 on the original front strut mounts, with 173,000 miles, causing the "cluncking" noise.
This is too funny and screams the old adage: penny wise, pound foolish.

Foreshadowing tidbits from KYB: KYB Americas | All about strut mounts

• A strut mount is like a sandwich. One side bolts to the vehicle, the other side to the strut. In the middle is a rubber-like insulating material. So as the vehicle moves and goes over bumps, the up & down impact pushes and pulls at the mount. The mount’s job is to cushion the impacts to reduce the jarring effect, noise and vibration that could transmit into the vehicle.
• Why replace it?
  There are two main reasons; age changes the density of the insulating material so more noise and vibration can be transmitted into the vehicle and the bearing portion of the mount wears.
• When to replace them?
  A simple rule of thumb is that if the struts or coil springs are being replaced because of age or wear, then also replace the mounts. A worn or damaged mount can cause a variety of symptoms so they should be inspected by a qualified technician. Disassembly of the entire strut & spring assembly is required to remove & replace the mount. Therefore replacing all worn components at the same time could save you from doing the work a second time.
• How to tell if the mount is worn. Drivability symptoms may include:
  • Clunking noises
  • Vibration
  • Loose, stiff or noisy steering
  • Tire alignment
  • Tire wear

If it turns out to be the front strut mounts:

• Are you sure he's your "friend?" People have few friends, but many acquaintances.
  
• Are you sure he's a qualified and licensed mechanic?
  • Violated sound automotive repair practice of not replacing front strut mounts, especially given 173,000 MILES.
• Feel free to buy Prius Chat a virtual $5 beer; the proceeds would go to their operating expenses.
• Guessing labor rate for redoing the front sturts will be $350-$500 range; due to a $57-$68 part per strut.
  
• In you future you won't make this mistake again, and will replace the "wear" items so you are charged labor only once.

KYB SM5215 (front strut mount), from $57.05 on Amazon.
Amazon.com: Buying Choices: KYB SM5215 Strut mount

Toyota 4860913010 (front strut mount), $67.99, at Camelback Toyota online.
2007 Toyota Prius Parts - Camelback Toyota Parts - Genuine OEM Parts - Free Shipping

 

So while your friend is at it, I hope that he has also replaced the upper and lower spring insulators. See my post here for a full list of the required parts (part numbers may vary by model year for the struts).

Hints Regarding Replacement of 2G Front Struts | PriusChat