My fenders are in decent shape. I would like to keep them that way.
Should I apply POR 15 to the inner lower portion of the fender to slow down any corrosion ? IE is there a reason not to put it on there ???

 

I think it would be a good idea. You would need to scuff sand where it would be applied and wash well first. Those look nice!

 

Believe it or not, the rust is caused by leaves and dirt that get saturated by salty water in the winter, and don't dry out!
Friend pulled the doghouse off a 72 Chevelle, and about 4-5 lbs. of wet leaves fell out of each side!!
I was stunned, as I never thought of it being a collection point!
I guess vehicles without separate cowl panels, are very succeptable to this, as they come in around the hood hinges!
He did Por-15 the insides of the fenders, after seeing this!

 

This mainly happens when cars are stored outdoors around trees.
It happens in the south, too. Tree debris gets in but can't get out. Water and moisture keeps it saturated and never really dries out. Wet leaves is often acidic and causes faster rot. Salty water much faster!
Here is what I found when i pulled the left fender...






My Caddy's fenders are filling up also. Very difficult to empty them out. With all the advances in automotive design, reduced debris retention has not been one of them.

 

Rob - at least your junk was dry!
This stuff was soggy, although the fender was almost pristine!

 

I'm working on the same thing right now . I'm actually in the process of removing that fender support . I tried to clean it up with the support on , but I cant get at all the rust , so off with the support . When I finally get the support off , I'm going to blast it and POR15 it ! It looks like that's what you will have to do to make it last in the long run . The only other way is to dunk it in acid or something ( or maybe vinegar for a few days ? ) and then coat it .... or pour some kind of rust ecapsulator in there .

 

You can also use a Epoxy which would be the right way to do panels , but I'm better set up for the quick application of POR15 so that's why I'm doing that .

 

wow , do you get fries with that mess ? and how in the heck did giant rocks get in there ?

 

Probably the same way as this crap got up into the front crossmember...




Personally I think this thing was partially flooded in a creek or something....

 

I would put POR on those fenders 100%. Best part is that you don't need to spray over them with any top coat. POR only needs a topcoat if it's going to be in areas exposed to the sun.

When I had my front end apart last year, I didn't take off the fenders, but did blow out all the crud that was between the side of the cowl and fender. Like the others said, mostly leaves, fluff and other dirt/crud. You'd be surprised how much acid leaves have in them. Then I put POR on the inside of the fender as far back as my brush would let me. My fenders didn't have any rust, and the POR is just good insurance.

 

I used por-15 on many parts of my car back befor I had the exterior painted.That stuff does not want to come off of skin.but seems to work well though it is getting more exspensive all the time.When I last purchased a can it was around $100 it is quite a bit more now.I used alot on my inner fenders and it turned into like a plastic.But it does not stick to smooth surfaces and likes rust to bond to.I have seen people put it on painted surfaces and in no time it peels off.You have to paint over it to avoid uv damage.I had a gallon of it for quite some time and to preserve it I put two layers of ceran wrap on the top then put the lid on and tapped it down.The ceran works well if you dripped some were the lid seals so the lid does not weld its self on.Strangly though latly I have heard of a few people using either truck bed coating or some rubberized coating on part of vehicles.

 

I use my air compressor also to blow out the crud in the fenders like once a year , but it's very difficult to get all of it out once it falls all the way down in there . This is why I'm going to put a screen on both sides under the hood so no more leaves and crud can ever fall back down in the fenders again . I will post some pics down the road of what I'm talking about once the fenders are done .

 

I can get pint size cans of POR here at a local speed shop for $10.00 . It seems to go a long way , just make sure you put the lid back on right away after you pour it good and tight or the top layer will harden in the can .

 

thanks for the replies. based on the responses I will scuff them with a wire wheel and clean them up w soap and water and put some POR 15 on them.

I found Amazon to have some of the best POR 15 prices. the vendors that fulfilled my orders were "advanced rust protection" in Mass and TCP global. I got the cleaner, the prep, the POR 15, and the POR 15 chassis coat. I plan to do my frame and control arms (currently front end apart for bushings, ball joints, springs etc) and the inner fenders

when I pulled the fenders off there was about an 8" high pile of leaves and debris under where each fender dogleg was attached. Fortunately for my car since I got it I have stored it inside anytime it rains or snows so the debris was dry. My wife doesnt care for that so much tho ....since her car goes outside when the cutlass needs to be in

I cant believe the condition of the fender either its surprisingly really decent

 

The crud in the trapped area can absorb moisture just from the humidity in the air. 8" of stuff in there is a lot! I'm planning keep mine clean by using air pressure directed from the door opening area.