Under my subaru there is a hole (caused by rust) the size of a quarter in the frame. The rust is really bad in this area. So far I removed the rust with a dremel around the hole and inside as far as the dremel reaches. I also made the hole bigger with the dremel, knocked against the frame with a screw driver causing lots of rust chips to fall out of the hole. But the rust still climbs the inside of the frame. I was thinking of spraying POR-15 up into the hole. This is what I am going to use to spray it: http://www.prp-porstore.com/merchant.mvc?Screen=PROD&Product_Code=PV&Category_Code=Supplies. What do you think? Is there a better solution to this?

I recently opened up a couple of rust holes into the frame of my wagon right in front of the back wheels. I'm looking for the same answer. POR-15 needs rust prep with metal-ready and then a water rinse, I think, and I wasn't sure that introducing more water into the frame was good. If anyone has tips, I would be very grateful.

I bought the metal ready. I was going to put some water in a squirt bottle and shoot some distilled H20 in there to wash out the metal ready, but I too don't feel comfortable about introducing more water to the frame. And I don't think the POR-15 will be able to cover all the hidden rust inside the frame (or at least it would be to hard to tell). Somethings came up, so I will not be able to apply the POR-15 until tomorrow. So if somebody can get a better solution to my problem before monday at 3:00 pm pacific time, then that would be great.

I would say cut open more area to get access and POR it right, then weld over a fresh metal pannel.

I could cut more metal out with my little dremel, but I do not know how to weld and have no access to a welder. Do I really need to have more metal welded in or can I just leave it with a hole? The rust is located underneath the car behind the front left tire.

In a general sense, without looking at it, I wold probably say it is not necessary. But what are your goals, to keep it a few more years and prolong life or to keep it forever? If you want to keep it, cut and weld, if you want to prolong, treat it as you can. That said, POR15 is a wonderful product and works great as a permanent fix where the metal is still sound.