A couple of weeks ago my friend who owns a 2008 JKU X was driving down the highway when he suddenly heard a loud clicking noise and the engine just stopped.

He towed it to the dealer where it didn't start. After a few sprays of carburetor's cleaner to the air filter duct the car started and the rattling noise repeated.
They opened the valve casing to find a single broken valve spring. There was no other damage present (luckily!) so they went ahead and replace the spring which after everything returned to normal.
The odometer is about 82000 miles, and as I mentioned this problem occurred on the highway, doing about 60mph on nice weather day.
Being it a spring, it is most likely a shear failure caused by fatigue. I attached some photos to help the experts get a view on the matter.



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I wanted to ask if anyone has experienced such a fault.
What should be done after such a problem occurs?
Do you replace all springs or do you wait for the next one to fail?
Is that covered with the drivetrain lifetime guaranty?

IMHO, I think that 80k miles is too early for such a failure.
What do you guys think?

-S

 

Did they look into the cylinder to check for valve/piston contact? Did they check for a bent valve?

Broken valve springs happen, but I wouldn't say it's all that common. I've been around cars for a long time and have only seen a few.

While 80k miles seems too soon for such a failure, it's somewhat unrelated to mileage. The spring must have had a small defect from the day it was made.

If it were my engine, I wouldn't see this as a sign the rest of them will fail anytime soon.