Bumper Stone Guard (Part 1)

Bumper Stone Guard – Rust treatment inside the panel

This body part has an unusual name for what it is, but doesn’t really do the job it suggests. Its called a Bumper Stone Guard according to some. It’s also called a Stone Deflector or a Bumper Filler, I have gone with the majority in what they call it in this case. This panel actually sits behind the bumper and it also holds the bottom valance in place, as well as support for the bumper and the bottom half of the fenders too. So it’s quite an important part of the front end but not really seen that much. The grill parts also locate on this panel and potentially could be a real pain to align properly. Pictures “Stone 1, 2 and 3” show how the misalignment has damaged the top and will need to be rubbed down and filled before it can go back on. This is what I intend Part 2 of this sub project to be all about. If this panel isn’t on properly with the fenders, the front of the car could look a little bit lopsided and very odd as a result!

I had taken this off at the same time as the fenders and the bottom valance. I need to treat the inside of the Stone Guard first before I work on the outside. Hence this update is called Part 1 and when I complete the top or the outside I will call that Part 2.


Firstly I have to remove all the flaky rust, paint and fillers as well as the loose underseal of which there was only a tiny part left! I used a drill with a wire brush wheel attachment and a more broomstick style wire bush to get right into the corners. I was well pleased with how it all came up after the brushing. Pictures “Stone 4, 5, 6, 7 and 8” show the inside before it had been rubbed down.

I applied the POR15 “Prep and Ready” via the spray, the directions advise to leave it on for at least 30 minutes. I left it on for more like 45 making sure it stays wet. This time game me the opportunity to tidy up and put things away. The chemicals within the solution attacks the rust and coats it with a phosphate ready for the main POR paint.

Pictures “Stone 9, 10 & 11” show the solution in place, you can also see the old surface rust and grime has been removed and looks quite different now. The underside almost looks brand new. Not bad for a 46-year-old bit of metal!

After leaving the solution on for the recommended time you have to rinse the solution of with water, so I took it out of the man cave, placed it on the grass and gave it some good ol’ treatment with the watering can. You are supposed to wait for it to dry before painting, but as the weather is not great at the moment, (at least  I didn’t look like Michelin man today!), I got some paper towels and dabbed it dry as best as I could. In order to make sure it was dry I waited for another 10 – 15 minutes to allow the air to dry it fully.

As I have document on the Fender inside treatments, I have added the POR15 paint, these are pictures “Stone 12, 13 & 14”. The first coat has gone on this afternoon and went on well, I will add the second coat tomorrow. It won’t be worth taking the additional pictures of the second coat as there will be virtually no difference that you can see from a photo, only that it will appear a more dense black.


I was pleased with how the metal underneath was solid and no holes in it from the rust what so ever, result. The wire brushing didn’t take long and the treatment looked to be doing its job OK. The POR15 went on well and settled to a nice finish. It will look even better with the second coat tomorrow.

The panel is the original and I don’t want to replace any of it, or any part of the car’s bodywork if I can help it. The only part that was not original was the addition of a thick washer that had been welded onto the bottom part of the panel that holds the valance. This was done on the inside to remake the hole for the nut and bolts to go in place. Nice idea, it works and not really noticeable. I will take a picture of that bit and maybe add it later to this post.

Note to self: Take all the pictures you need!

Here’s the gallery from the start to finish, well of part one at least!

16th December 2012 – update:

As promised I took a photo this morning of the damaged part of the bumper guard. It had a washer welded into place to make the hole again to support the fitting in place. As you can see the job has been done quite well. fairly thick washer with the hole the same size as the others. The bottom has been filed flat to look “stock”. I finished the second coat of the POR15 this morning and took another couple of hours to do. Looking good, shame nobody will see it when it goes back on the car. Never mind – I know it’s there and that’s the main thing I guess.

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