Surface floor rust (outside), what to do?

[Jayru]

Hi guys,

I've been under my z today and found some external surface rust. I know it's only external because i pulled the carpet up and their is no rust inside.

I don't have the time or money to completely strip the undercoating underneath, so i'm wondering if i can scrape the immediate undercoating around the rust off, scuf the rust up, and coat it with por 15.

Do you guys think this will be a good fix? That will stop the rust from going any further correct? Let me know what you guys think.

Thanks,

Jay

[e_racer1999]

por is easy fix? yes. will it guarantee that the floor won't rust out? no. your best bet is to strip the undercoating (no matter how much that's gonna suck) and get all of it (if there is more).

[Jayru]

Jason,

So you're saying that the por 15 will stop the rust where i coat it, but it will rust in other places, or that it will rust anyway even with the por 15?

If i striped the whole floor of undercoating, i should por 15 the whole thing?

Thanks,

Jay

[Bambikiller240]

In order for POR to do ANYTHING for you, you MUST strip the metal of ANY AND ALL PAINT. POR must be in direct contact with the metal. You should read up on how POR must be applied before considering the use of it. The metal must be PROPERLY prepared for the application of POR or you will be wasting your time and money.

There are many threads on this. Use the search function to find them.

[Jayru]

Actually only one thread on what i wanted to do and i read it. And i was not happy with it's contents, which is why i posted this question. But thanks for the search concern...

[AChev]

You said you lifter up the carpet to check if there was rust there. Does youre car not have the tar paper linging on the floor? If you did not remove it, that should be there covering up the metal

[e_racer1999]

^that's true.... the tar might be (and probably is) painted body color, so it may appear as though you are looking at the metal...

what i am referring to by saying that it will rust in other places is murphy's law of rust: if there is rust in one spot, there's rust somewhere else.

[Bambikiller240]

Actually only one thread on what i wanted to do and i read it. And i was not happy with it's contents, which is why i posted this question. But thanks for the search concern...

If all you found was one thread on the application of POR, you aren't using good search terms. POR15 application to Floorpans has been discussed literally dozens of times.

What specific questions do you have?

[Ed]

POR15 application to Floorpans has been discussed literally dozens of times.

I'm sorry Carl, your wrong. We have not discussed this dozens of times. I think it's been discussed hundreds of times.

[Bambikiller240]

(Ten Charecters)

[Jayru]

If all you found was one thread on the application of POR, you aren't using good search terms. POR15 application to Floorpans has been discussed literally dozens of times.

What specific questions do you have?

My specific questions:

1) Is it ok to scrape the undercoating (and paint) off the visible rust and coat it with por 15. then lightly undercoat the (por) spots to protect the surrounding non rusted, non por'ed area. Would that fix the problem in those areas?

2) if it is starting to rust through (good point about the tar paper Schevets i didn't even think about that :stupid: ) Then only treating the underside would not stop the rust? Or would the por 15 attack the rust as a whole, chemically chainging it on the other side (inside the floorboard) as well (even though it hasen't been physically painted on the inside)?

Specific enough?

I still think it's just surface rust, i guess i'll know when i hit those spots with a sander/grinder. I don't want to go through the hassle of striping the tar paper if it's not all the the way through.

[Bambikiller240]

My specific questions:

1) Is it ok to scrape the undercoating (and paint) off the visible rust and coat it with por 15. then lightly undercoat the (por) spots to protect the surrounding non rusted, non por'ed area. Would that fix the problem in those areas?

POR will only protect metal that it is direct contact with. Any metal that you strip and is not prepared properly and treated with POR will be subject to potential rust. Undercoat will not protect the "surrounding non-por'ed area" from developing rust. (that's how the rust you want to treat got there)

2) if it is starting to rust through (good point about the tar paper Schevets i didn't even think about that :stupid: ) Then only treating the underside would not stop the rust? Or would the por 15 attack the rust as a whole, chemically chainging it on the other side (inside the floorboard) as well (even though it hasen't been physically painted on the inside)?.

POR will stop rust that it is in direct contact with. If the metal is rusted through and you don't treat both sides of the panel, the rust will continue on the un- por'ed side, thus you won't have accomplished much.

PS: It is VERY COMMON for there to be rust under the tar-mat. What looks like minor surface rust under the mat often turns out to be significant rust. (personal experience talking here)

The logical time to remove the tar-mat is when you see ANY rust on that side of the panel (in other words, before it has ruined the floorpan so that it must be replaced)