CV boots require an ounce of prevention and regular checkups

Dear Car Talk:

I enjoy reading your column. I have a 2017 Subaru Forester with 50,000 miles. It runs fine.

The question is: Can you recommend anything I can spray or paint on the CV boots to protect them?

When those things get ripped, it’s a short time before the road grit gets into the bearings, and then you’re looking at an axle replacement! It seems like an ounce of prevention is worth a pound of cure for this situation.

— Lloyd

I’d spray them with concrete, Lloyd.

No, there’s nothing I know of you can spray or paint on a CV boot to protect it. Like other all-wheel-drive cars, your Forester has eight CV boots. Inner and outer boots on each of your four axles. The boots cover and protect the CV joints, which transmit power to the wheels while allowing the front wheels to steer and all the wheels to move up and down.

The boot is a cone-shaped, rubber bellows-like thing that looks kind of like one of those Kong dog toys.

It’s packed with a special grease to keep those CV joints continually lubricated and to keep dirt out of the joint.

And while CV boots can last a long time, they can get cracked or torn. And once that happens, grease leaks out and dirt gets in, and eventually, the CV joint fails and starts making noise when you accelerate on turns.

So, what do you do? Well, other than not driving your Forester through the Amazon, there’s not much you can do to protect a CV boot from getting damaged. If you drive over a big tree branch or a tourist using a selfie stick, you can puncture or tear a boot. It can also crack due to age.

The best thing to do is simply have it checked regularly when you go in for service. Especially the front boots, as they’re more vulnerable.

It’s a simple thing to do when the car is on the lift or by getting under the car with a flashlight. Your mechanic can eyeball the CV boots and even run his hand around them to make sure there’s no grease leaking out. When a CV boot fails, it usually slings grease all over the place making an enormous mess. So, it’s easy to detect.

If you run over something large and suspect you’ve done some damage, that’s a reason to go right in and have the car looked at. Otherwise, just ask your mechanic to check them when you’re in for regular service, and hope you catch a bad boot before your CV joint is toast.