aprotogerellis

So I spent a number of weekends over the summer trying to sort out the small bits of rust that have developed around the door sills and wheel arches. After a bit of research I'd concluded that POR15 seems like the best stuff around.

So I went through the whole process of sanding the area, applying a number of coats of POR15, a number of coats of white paint and then a number of coats of clear.

And now, 6 months later its all come back in anger...

Surely POR15 is meant to keep the rust at bay? I didn't sand 100% of the rust away but that's meant to be OK...

Am I doing something fundamentaly wrong here?

Another alternative is sanding every spec of rust off and then priming with a zinc primer - any experience as to whether this is more effective?

Thanks,
Alex

xsboost90

did you POR15 inside and out or just on the outside?

aprotogerellis

Sounds like a leading question

Wherever possible I've done both sides but in most cases I can only get to one side...

aprotogerellis

So, any opinions on what is more effective: POR15 or zync primer?

JonH

I've found that you have to pretty much get all the rust off down to metal to stop it from coming back, also have to feather sand to metal past any rust spot that's obvious. Also have to treat or convert the bare metal with a rust converter (like a OSHPO) to prevent flash rust before a POR 15 type paint. ALSO have to clean the surface real well with a body shop fast cleaner before and after sanding so you don't sand in oil, wax, etc. It's a pain, I know I own a 914!

Ben951S

por15 is supposed to be pretty good stuff, when used correctly? They also have the degreasing product, and metal ready, as well... You have to encapsulate the rust though, so just doing one side would be a problem. It all depends on the rust, was it surface rust, or a hole all the way through, that would be hard to 'reach the back of'. You could always try a syringe with a bent needle, or something. =(

xsboost90

i used alot of products on my old 914 rustoration. You have to do both sides if you treat the rust. I was using weld through primer for panels i welded back on, drilled holes and used a straw w/ the inner panel body spray 3M, used alot of POR15 and undercoating.

aprotogerellis

Good advise guys, thanks... the job will wait until the weather improves but I think I'll be trying all of the above and see what happens!

KuHL 951

Surface prep is the most critical step in the entire POR15 process. There is no such thing as a 'rust converter'. All POR 15 does is encapsulate the existing damage. Corrosion will start all over again if the seal isn't 100% holiday free . I'm more impressed with hi-build, zinc rich epoxy primers. At least they are fairly surface tolerant of a marginal surface prep but provide a sacrificial zinc coating if moisture does get through it in the future. Getting a good prep is difficult at best in the rocker panels and fender crevices unless you have the proper blast equipment. POR-15 is a decent product but it doesn't really eliminate the problem, it just hides it for awhile.

harrisonrick

The best 100% cure for rust is to cut it out, and weld in new steel.

theykallmekem

pictures ?? i want to see how bad it is. and i agree just cut it out and use new metal

Jim 944S

You'd probably find more experts over in the 911 forums!!!

Jim 1987 944S

KuHL 951

I always thought the 914 guys had the most experience

JonH

Maybe, but if you want guys you can call experts on rust you have to ask the 914 or 356 crowd. Unfortunately, I speak from experience

Pcar944

Part it?