85 Fullsize blazer, lots of floorboard rust, please advise


Junior Member
My 85 Blazer I just purchased for $700. It is legal and on the road daily. The flooring is basically rusted all around the cab, as well as where the back seat is mounted. I am seeking advice on parts, and whether or not my mig welder will be up for the challenge. Also the guy i bought it from told me it was a 350 but the firewall sticker says 5.0. Any way for me to be sure? I bought it as a beater as I have a new 99 wrangler. But I have fallen in love with the old girl. One last question, wiring, obviously rust could be damaging my wiring, but the right turnsignal works only when the headlights are off, WHY?


Junior Member
You can see if JC whitney has a replacement floor panel or


i just looked in my catalog and Mill has one, cab floor pan 39" X 25" but not for a 4X4

they also cary numerous other parts sheetmetal and some gas tanks plus senders for gm vehicles plus trucks.

I would buy the replacement panel, get a cutting wheel, cut the old floorpan off and weld in a new one. Or you can do what a guy paid me to do. Go to home depot, buy sheetmetal and use rivots and do a cheap temporary fix. I painted it and sealed it with silicon from the hardware store plus rubber undercoating.

If you have a mig welder already, i would buy a replacement panel, and spot weld it in, then later weld in the places that havn't so it doesn't warp. Seal the seams with silicon then paint it. Then undercoating the panel from underneath.

Things to look out for, brake lines, fuel lines, and anything that you might cut into or catch on fire. Disconnect your battery also while welding.


PlowSite.com Veteran
i have the same year blazer and many in that same body style are in the same condition. you want to make sure it is safe but i would not spend too much money fixing it it will never end if the rust is that far along make sure your inner and outer rockers are goog then get some old carpet and put down to keep the drafts out if you using it for plowing just keep it safe and running good if you want to rebuild it all to get all looking good you will really need to take it all apart, all of it to inspect for every little bit of rust and then put in new metal

mine is a 305 i will bet its the same .........it is not that big of a deal on a blazer(only 1/2 ton) you cannot really haul much any way most 350 parts interchange for replacement pieces or performance mods


Junior Member
I have the 88 blazer and the motor is a 5.7L. I had extensive rust under the rear bed. I could not find anyone who was willing to replace the bed because the rear bumper and underlaying framework also had to be removed and repaired. I ended up using fiberglass mats to make the repairs since none of the rust was on stress points. I used an rust converter primer paint prior to using the epoxy/fiberglass mat repair. The repairs are solid but I figure that it will only last a couple of years. With 99,000 miles on the car, I am planing to replace it then. I would recommend that you lift up the carpet and underlying material to expose the bed prior to making any major repairs. This may be a lost cause. Good Luck, Rich.

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