I just put my summer tires on, and as I was jacking the front of the car, I noticed a significant rust hole just behind the Jack point in the drivers front end. I am talking about where a shop would put the lift pads. Not the places where the car jack connects to. I would say the whole is about an inch or an inch and a half diameter. Is this a major concern?

You might get a nibbler and open up the hole to sound metal - then -

Many high end manufacturers now glue their cars together - I saw several such a Lotus and Ferrari pn How It's Made.

They do test strips and check them for hold - If the bond is bad, the car is repaired or destroyed.

You might just glue a patch on.

Several years ago, our hazmat team had a drill at the Duco company - they mentioned that the first automotive use of glue in production cars was a Ford model and their glue was used on its front bumper.

Hi, can't remember my password and waiting for reset link. There is a product called KBS patch that works very well. Comes in various sizes up to 9 x 11. It is a peel and stick patch that is activated by UV.... either natural sunlight or for undercarriage or cloudy days by use of a UV flashlight available on the site. The stuff sets up hard and really sticks where it is placed. I had occasion to use it on a rust perf on my pickup... very highly recommend. Just resist the temptation to poke at it before totally set up since it will definitely make the surface distort, don't ask how I know this.

Check the other side of the car, if it is the same then sand paper, primer, black paint.
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Keeping it running is better than buying new

Thanks Both,

Klaus, are you suggesting that there is no real need to fill the holes? I notice three rubber plugs in the area of the rust hole, and it occurs to me that, had I seen and removed those a while ago, I would not be facing this issue now. Is that incorrect thinking?

Thanks again, as always.

IMHO - If you intend to keep the car any length of time I would fix it. At that size it should be pretty cheap to fix. It will continue to grow and get more expensive to repair. Eventually it will become a safety issue. Search for other rust holes/spots before jumping in to any repairs.
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Will I buy another Volvo??? We'll see....