Did some rust repair on our P5 today (pictures included)

RWatters

Member
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16.5 CX-5 GT
We've had our P5 for 3 weeks now and when I was detailing it a week or two ago I noticed some serious rust in the engine bay and then some surface rust forming under the side skirts towards the rear of the car. After reading how many of these cars are having rust issues I decided to try to get ahead of the game in some of the problem areas and ordered some POR15 to help seal this stuff up and hopefully prevent it from spreading. For those of you who don't know what POR15 is, they are a company that offers various products to help stop rust from spreading and they are VERY popular in the classic car community. This stuff came highly recommended Here is the kit I ordered:

http://www.por15.com/SUPER-STARTER-KIT/productinfo/SSKB/

To get started I popped the engine bay and removed as much rust as I could. It was BAD. It was completely rusted through in an area or two. This image was taken AFTER I cleaned the area and removed most of the rust. This was taken during the prepping process so it's a lot cleaner than it was before:

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I knew I was in for a hell of a battle and was pretty upset when I saw all of this. What was the culprit of all of it?

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This bastard. The whole outside edge of the plate wasn't sealed very well so it was rusting through there. I'm not sure of this is on all of the cars or what, but it's the culprit for all of our rust issues. When this image was taken I was cleaning and scrubbing it so I could get a good seal from the underside as well.

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Here is the engine bay getting cleaner. After a few more rounds of prepping and scrubbing I was ready to apply the POR15 that will hopefully save this engine bay!

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As you can see the POR15 is now applied. Yup, they make it in silver so it's not too bad to look at! After this was applied I wanted to seal up the areas that had completely rusted through. What I decided to use was a product used to seal holes in exhaust. It's a tar-like product that you heat up and then apply. Once it is heated and applied it's really not going ANYWHERE. Here you can see me getting this started below:

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The black is the exhaust stuff. I ended up covering the entire area with it and then painted over it to make it look silver again and to try to seal up the edges a little as well. Here is the finished engine bay:

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MUCH better don't you think? Now, for the culprit in the fender well that caused this whole problem.

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I sealed the edges as much as I could with this stuff. I then decided to go a step further and apply the same exhaust sealer around the entire thing to ensure that water couldn't get through and start the whole rust process all over again:

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Once done I painted over the ENTIRE area to make sure water didn't have a chance to make it in anywhere!

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I plan on getting some black rust protectant and coating the whole area so it looks a little more at home in the fender area.

Area one completed!
 
As for the rest of the car:

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This is the back panel. I had already started removing paint when this picture was taken. If you look closely you can see some bubbling. I took care of this as well.

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Removing even more paint.

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Here is the area just above the back bumper. The bumper had been wearing down on the paint and it was starting to bubble. I removed the whole area and exposed even a non-rusting area so I could cover the entire thing.

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Starting to tape up the area needing attention.

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Painting away.

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Done! The area around the edges is a little rough because some tape was still on there and the tape left a little residue as well. It was oooold masking tape I found in a drawer.

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The opposite side was in the same exact shape so I treated it the same exact way.

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Drivers-side area above the bumper painted. For some reason I didn't take pictures of the other side once I was done. Whoops.

All done with it! I wasn't too concerned about the job looking insanely perfect and beautiful because the side skirt is just going to cover it up. My understanding is that this paint is VERY tough and should hold up to the abuse from the side skirt, but I'm probably going to try to put a small film of something on the edge of the sides skirt to try to keep from rubbing it away just in case.

All-in-all it was around an 8-hour-job but hopefully it's going to be completely worth it in the long run. The other side of each panel area effected by rust had ZERO rust on it so I didn't touch it right now. I still have the side skirts off because I broke a few of the clips when removing so I have to order them from Mazda on Monday anyways. Before putting them back on I may go back in and touch up a few more areas (more of the passenger-side rear area where the undercoating/rust-proofing is starting to show signs of rusting) but otherwise every area of the body panels that was showing any signs of rust has been taken care of!
 
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I've POR 15'd the rear wheelwell lips and where the rear bumper meets the quarter panel, I actually ground all the surface rust off with a dremel, then prepped with marine clean and metal ready then applied the silver POR 15, which has fine bits of aluminum in it, then a couple coats of light grey primer. I also did inside the rear wheelwells and then topcoated them semigloss black. I am now in the process of repainting the rear quarters and clearcoating all the way along the roof pillars to the end of the a-pillar. So I'm learning how to use spray guns and DA air sanders which is something I always wanted to do.Did you use an etcher like metal ready on any bare metal? Where do you live?
 
I've only seen rust on my rear hatch where a few spots of paint r missing... and on my exhaust manifold of course. but other than that none at all
 
I've POR 15'd the rear wheelwell lips and where the rear bumper meets the quarter panel, I actually ground all the surface rust off with a dremel, then prepped with marine clean and metal ready then applied the silver POR 15, which has fine bits of aluminum in it, then a couple coats of light grey primer. I also did inside the rear wheelwells and then topcoated them semigloss black. I am now in the process of repainting the rear quarters and clearcoating all the way along the roof pillars to the end of the a-pillar. So I'm learning how to use spray guns and DA air sanders which is something I always wanted to do.Did you use an etcher like metal ready on any bare metal? Where do you live?

Wow, you're doing quite a bit of work there!

I used Marine Clean to clean it, and then Metal Ready to remove the surface rust (combined with some sand-paper). Once done I rinsed the whole thing off, dried it, and then applied 2-3 coats (depending on the area) of POR15. I didn't have any primer/paint with me so I didn't apply any of that, but since it matches so well I'm not sure I even will anyways.

I found that this starter kit was very easy to use just by following the instructions. Dry time between coats was around 2 hours for our spots which is why it took so long to do it.
 
nice work. is rust a big problem on those cars?

Considering ours is a 2003 and it had surface rust in a few spots already, I'm going to say yes. It's possible that it's just our car, but with as many rust threads as I've seen on here I'm not thinking it is.
 
I love POR-15. It's great stuff. It has been holding strong now for about 2 months
 

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Job well done. I think this answers my question of what to put in rusty areas. I've got a few in my doors because the paint and rock chips. :eek:
 
I don't have rust so to speak, but man I have a BUNCH of rock chips on my hood and my front end. No way to really prevent that....but maybe a carbon fiber hood will make me feel better. :D
 
nice work. is rust a big problem on those cars?


oh yeah!! come to canada. every 2nd P5 on the road has rusted out rear fenders. mine included. my rear bumper is sagging on one side since the metal is so thin from all of the rust erosion, its beyond repair other than dropping a grand and cutting out then welding in new metal. damn southern ontario not allowing studded winter tires and POURING salt all over the roads instead.

to the OP. good work and be sure to keep on it.
 
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