If You Can't Take The Heat -- Check Your Heat Shields

Dear Car Talk:

I have a 2005 Infiniti G35 with 134,000 miles. The heat shields, top and bottom, have rusted on my catalytic converter.

Can I just replace the heat shields on this vehicle? Could you tell me an estimated cost and time required to have these replaced? From reading your column, I understand it is important to replace them. Thank you. -- Wendy

You're right, Wendy. I think it's important to replace your heat shields. But hardly anybody does it.

The heat shields do what? They shield heat! Your catalytic converter can get as hot as 600-700 F when it's working hard -- even hotter if it's plugged up and malfunctioning. The heat shield on top prevents that heat from melting your carpet, or, even worse, your Manolo Blaniks. The shield on the bottom keeps the converter from setting fire to grass or leaves or anything else you park over that's flammable.

I don't know the exact cost of the heat shields for this car. I would guess it's going to cost you several hundred dollars. But with 135,000 miles on your car, I do worry that your converter itself may be nearing the end of its useful life.

So, another option, if you plan to keep the car for a while, is to replace the whole converter now. It should come with its own, new heat shields attached. That's going to run you an easy $1,000. But you'd hate to spend $300 for heat shields and then need a new converter in six months, right?

If you have a mechanic you trust, talk it over with him. Ask him to look at the exhaust system, see what kind of condition it's in and then give you real estimates for both jobs. Ask him what he'd suggest.

While fires are rare, they do happen, Wendy. So, one way or another, I suggest you get your heat shields replaced. And until you can get it done, try a pair of asbestos booties for your Manolos.

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