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I've got a new to me 1986 pickup that I need to do some frame repairs (rust) to. Does anyone have regrets from POR 15? I understand it needs prep and primer to be successful.
Requires very extensive prep. You'd need to 100% strip everything off and encapsulate every square inch (including between lap joints and in inaccessible areas) for it to work. I used it early on and my experience has been if you get any scratches or miss any spots, moisture can get behind it but then has nowhere to escape. This leads to rust that builds up underneath the POR-15 and is actually worse than if it wasn't there. Eventually the nice black layer of POR-15 flakes off and you are left with wet scaly rust. Other people have had good experiences. Slacker on here recommends it, but he does frame off restorations as his job so has time and ability to put that much effort in.
Once you fix whatever you have to fix, I'd recommend an oil based undercoating like Fluid Film. It sprays on and sticks like crazy. Thick and tacky oil, almost a light grease. It also creeps into joints so you can protect inaccessible areas. Nothing rusts when covered in oil.
I have used it back when it was written up in every auto magazine and blog. I did the underside and axle housing of my 67 Camaro. Followed the prep instructions closely and it did what it claimed, but i probably would have been just as well-off with a cleaning, rust converter and topcoat. After all, i’m not driving this car on salty roads, or even wet roads at this point in its life.
I've got a new to me 1986 pickup that I need to do some frame repairs (rust) to. Does anyone have regrets from POR 15? I understand it needs prep and primer to be successful.
Do NOT use primer under POR15. But yes, you do have to prep it. Knock the loose stuff off, wash, etch, dry and paint. I use a LOT of it, I always keep some of the 4 oz cans on the shelf.
Originally Posted by arlindsay1992
Requires very extensive prep. You'd need to 100% strip everything off and encapsulate every square inch (including between lap joints and in inaccessible areas) for it to work. I used it early on and my experience has been if you get any scratches or miss any spots, moisture can get behind it but then has nowhere to escape. This leads to rust that builds up underneath the POR-15 and is actually worse than if it wasn't there. Eventually the nice black layer of POR-15 flakes off and you are left with wet scaly rust. Other people have had good experiences. Slacker on here recommends it, but he does frame off restorations as his job so has time and ability to put that much effort in.
Once you fix whatever you have to fix, I'd recommend an oil based undercoating like Fluid Film. It sprays on and sticks like crazy. Thick and tacky oil, almost a light grease. It also creeps into joints so you can protect inaccessible areas. Nothing rusts when covered in oil.
As I posted in another thread where you posted this. It does not need to be 100% stripped, just knock off the loose stuff. Washed and etched. If this is done, moisture will not get behind it like you describe.
I POR15d my frame on my 4runner without removing the body or drivetrain. I spent several hours on a creeper with a wire wheel on a grinder cleaning it up. Rinsed it off, washed with their cleaner and a scrub brush. Gave it a serious rinse with the hose. Let dry. Doused with Metal Ready. Let dry. Then painted. Took a few days in order to make sure everything was really dry before painting. I bought a Harbor Freight HVLP gun specifically for that job, and was pretty pleased with it, although it made it really easy to lay it on too thin. POR15 really needs a pretty thick coating, so it's best if brushed on.
I've painted suspension arms, brake calipers, bumpers etc. I've touched up bare metal on body panels. I even painted my wife's flower pot stand with it. It will fade in UV light, so if you care about how it looks, top coat it.
I've used their high temp products on exhaust with decent luck (after 3 MN winters, my mild-steel aftermarket mid pipe on my Outback is still pretty rusty, but I think it slowed the process considerably).
I used their gas tank sealer on my 4Runner last summer while I had things apart for the 1UZ swap. I haven't put fuel in the tank, but the stuff I spilled on the driveway has held up extremely well...
I buy the prep chemicals by the gallon (sometimes I use Simple Green as a degreaser). I actually have a bucket of Metal Ready in my garage, and I drop rusty parts in it, as the rust just dissolves off, and the acid can be reused.
I did the quarters on my 4Runner about 10 years ago.
Before (notice how the Cleaner dissolved the iron ore mud in the area):
I have bashed through this coating a few times, and just touched it up with bedliner in a rattle can, no flaking or rusting (I will admit, this truck is NEVER driven in the winter).
I plan to clean it up and put another coat on it (I re-relocated the gas tank, so there's a section of the frame that is now accessible that wasn't) this summer. And I'll probably use some sort of rubberized undercoating as well to protect the POR from damage.
Thanks all for the information, and thank you for the thread links. I had found one of them but the other was really what I needed to see. After reading this, since two points on the frame past the cab are going to be included in my cosmetic, I think I'm going to POR 15 the exposed sides for mild aesthetics, then Fluid Film everything else.
This truck is going to see extremely harsh conditions as a recovery/disaster relief/missing hiker vehicle and I foresee needing to be able to cut, weld and patch damaged sections and clean the frame easily. I think fluid film will be the best match.
Most of the bed body rust is getting cut off and I'm not looking to replace most of the sheet metal since I'm going to be mounting underbody steps/rocksliders and area lighting to help me see when I'm using the truck at night. It will have LOTS of area lighting. Any advice/suggestions on mods to make the truck extreme duty trailworthy is welcomed
I redid the entire frame on one of my trucks in POR15. It was a frame off so I was able to prep & clean properly. Followed directions, Brushed on POR15, and top coated with brushed on enamel. Looked great. It's been in the garage for the winter. 9 months later I can see the rust coming through again. For the amount of work and the money I put into this ($400 in POR15 alone) I would have been better off taking it in to be sand blasted & coated. I blasted and coated my 1st truck 10 years ago and still looks new.
For all the work and mess with this I can not recommend POR15. Find another way...
Apr 15, 2021 | 10:47 PM
