I have had excellent results sanding both sides using disc sander or side arm grinder, then coating inside and outside with Bondo, the auto body repair Bondo. We still have a mower I did this to over 20 years ago and it is holding.

Walt Conner

David
If the deck is cleaned then sanded to bare metal. JB Weld may work if the holes aren't to big. But it will get eroded away if you mow in sandy soil.

A product that is known locally as "Fiber Hair" auto putty is much stronger and durable than Bondo. It has fiberglass strands mixed with the putty. It works much like Bondo by being two parts, Puddy and Hardener. Once it cures tho it is much harder to sand and shape than Bondo. So If you go that route test a small amount on something other than the deck to get a feel for the stuff.

I too have repaired my 84 dynmark push mower bottom crawler deck with sheet metal, rivets, and bondo. After 6 years I'm still using mine.

Obviously we must use whatever is available to us. If enough money is available a new deck could be purchased. JB Weld for a rusty deck is not the best plan, but it might work. I have a plasma cutter and a MIG welder which I use on my similar problems as they occur.

you are kidding? You can really buy new decks for lawn mowers? I'd like to hear more about this because our sandy soil works on the decks and the blades. DH was just talking about fixing a hole in the deck of the old Murray. I think he said it was an 80's model and it's still going. I'm going to write down this stuff you guys are talking about and he might can use this to repair the hole in it.

I thought I'd toss in my $0.02 to the mix. Whenever I need to "patch" a wide gap with JB Weld, I cut a small section of fabric from an old pair of my wife's panty hose (get her to donate an old pair, one pair is probably all you'll ever need) that is a bit larger than the defect or damage that needs fixing. First you need to clean around the edges of the hole down to bare metal. Place the swatch of fabric an inch or so away from the edge of the hole and tape it down with duct tape or masking tape. Stretch the fabric across the hole and tape it down on the opposite side, do the same in the other 2 directions. Mix a small amount of JB Weld and apply it along the entire length of the edge of the hole using a popscicle stick or comparable tool, pressing the JB Weld through the fabric. Allow this to cure. After that has cured, remove the tape and trim away the excess fabric (not the fabric stretched over the hole) from around the edge of the first application of JB Weld. Mix another batch of JB Weld and apply it over the patch area covering the fabric and overlapping the original application of JB Weld. If you can access the backside or underside of the patch, applying a layer of duct tape or masking tape across the fabric there will make it easier to keep the patch "flat" or level. After thoroughly curing the tape can be removed. To "keep" JB Weld vital after it has been opened, put your tubes into a "baggie" with the dispensing ends of tubes opposite each other and store in the freezer. The sub zero temp practically halts deterioration and you just have to take it out and set at room temp for about 15 minutes so you can squeeze it out.

Davidld, I'm with you, can't get myself to get rid of something that still works and runs good. I've about wore out the second motor on my old Snapper walk-behind but the mower is still works great. I put a Tecumseh 5 hp on it 14 years ago and the darn thing still starts on the first pull. Smokes when you put a hard load on it but just keeps going. Keep thinking I really need to replace it but darn it--- it still runs fine. I used that bondo with the fiberglass strands in it to fix the dashs on my old Massey Fergursons, they're plastic and crack at the corners. Scuffed up the underside and put about a 1/4" thick layer on. The dashes are a lot more solid now and it stopped the cracking.

THere is a product called Steel Flex . It is a epoxy base with powdered metal and a activator. comes in 1/2 & gal size. I use it on the bottom of my airboat . I run over oyster bars when fishing the flats on Fl west coast. And it only scratches it .Applied with a putty knife it will last years. Some NAPA stores can order it ,or where ever fine airboats are sold.