How do you fix this rust?

[wgwollet]

I have rust on a 1972 911T in the truck area....its not rusted thru.......

How would this be fixed? and what is por15?

thx

[500_19B]

The second picture indicates a badly rusted suspension pan. At a minimum, you must cut out and weld in a new forward section for the suspension pan as well as the fuel tank support.

This is not unusual at all. It is typically caused by a leaking battery that was not properly neutralized.

I had to do this. This was my experience:

Battery-area surprise! - Rennlist Discussion Forums

[T77911S]

i would clean as much of it off with a wire wheel, then pour lots of OSPHO on it, i think advance calls it something else now, let it sit for a few days, clean it up again then put extend on it.
ospho is osphoric acid, great stuff. it eats the rust. extend does too, but not as good. the extend puts a better coating on top to prevent it from rusting again.

if there is something newer or better out now, someone will chime in.

[ossiblue]

What you show in your photos is very typical rust, especially in the early cars. The area of real concern is in the bottom photo--the gas tank support. You need to explore that area very carefully as the rusted area shown covers the unseen suspension pan which is a critical component. Typically, rust in the area shown has a counterpart hidden underneath in the suspension pan. You need to get under the car and carefully but aggressively check the underlying sheet metal where the A-arms bolt to the chassis. If you find rust/weak metal on the underside, you are looking at repair or replacement of the suspension pan and gas tank support.

More pictures at a closer range will help diagnose what's going on, as well as pictures of the underside. The photo posted looks like surface rust but the extent of it and the fact it's an early car all point to more investigating. Worst case is replacement of support and pan which is a very common task on early cars. Not cheap but doable yourself if so inclined and skilled.

[irl]

Search the forum for suspension and battery area rust. There are a ton of great threads. Unfortunately this area is extremely prone to rust and it may be a lot worse than you think. Hopefully not and you can just surface wire brush with a drill and use POR (paint over rust) paint. Also, Google POR 15 and read about it.

Here is just one link to start, but there are many.

Suspension Pan Question

[RWebb]

battery clamps are toast also

[HarryD]

Wow,

You have several things that would concern me.

Batteries: How are they fastened to prevent them tipping over? You isntallation is very dangerous. There are numerous battery threads on how to properly install batteries. For an early car, this is a good one: duel battries. There are plenty more as well. Some good search terms to use are optima, miata, oddessy, and Sonnenschein.

Rust: Your front suspention attachemnt poitns are directly below the rusted section you show. Often the greater damage is below. Before you attempt to repair what yu show, inspect the under side and be sure your suspension attachment points are STRONG. If they are, you can treat the rust by several means. POR-15 System consists of several treatments in suceesiion. Buy all the products (Metal ready, marine claen, POR-15) and follow the instructions. You can also use rust killers like Naval Jelly, Rust-mort (and others) followed by tradtional priming and paintings.

If they are compromised in any way, you will need to replace the front suspension pan and gas tank support. A good Porsche Shop can do this easily.

Good luck. Let us know what you find.

[GaryR]

Is that the gas tank charcoal cannister attached to the battery? Looks like it's rigged to be
a bomb!

[wgwollet]

Thanks for the replies.....I have some work to do

[tharbert]

Because those batteries are the wrong size, they don't fit up into the battery trays. As a result, the left battery interferes with the charcoal canister and the piping. I have the same problem although mine does fit into the tray but hangs out too far. You ought to consider deleting one and moving the remaining battery to the smuglers box...after the rust repair. There are a number of examples if you search the forum here. That's on my list of things to do.

[JeremyD]

You need a cover on those positive terminals too - and hold downs - and ... If I were you - I'd pull your gas tank so you can get a better view on the front suspension pan. It's the stuff you can't see that will get you...

[Fritter]

A battery tips over, contacts get bridged, a spark happens, gas tank and charcoal cannister are very close with questionable rubber lines most likely....YIKES!!!

[bfunke]

Can't tell from pics but hopefully only superficial damages. Recommend replace batteries with Optima. I had to repair some battery induced corrosion in my car. Came with a leaky battery from the PO. Interestingly, paperwork had a receipt from a shop recommending battery replacement few years prior which PO declined due to cost. Yes the Optimas cost a few buck more but well worth the added safety and reduced leakage.

[1973911t]

i use some stuff from my local body shop cant recall the name. You put it on the infected area and let sit it kills the rust and turns it a blackish color. most paint and body shops have this

[Flieger]

Por-15?

[HarryD]

Contrary to popular belief, POR-15 (a good product) in and of itself, is not a rust killer. The POR-15 system consists of "Marine Clean (a degreaser), Prep & Ready (a rust converter like Rust Mort, Naval jelly etc), and POR-15 (epoxy coating).

You can use Naval Jelly (or Rust Mort) followed by a good primer and paint with about the same results.

If you like a simple, two step process, many of us use a product like Permatex Rust treatment


or Loctite Extend



or the NAPA Autoparts equivalent.

We then use the appropriate top coat.

[m110]

Originally Posted by Flieger

Por-15?

terrific stuff, just like the final coat of carnuba but in terms of stripping, prepping, treating and sealing off a steel oxidised area for (hopefully) forever

[Series900]

sandblast,epoxy paint,schutz,paint. por 15 does not kill anything imho

[Hodgey]

Originally Posted by jeremyd

you need a cover on those positive terminals too - and hold downs - and ... If i were you - i'd pull your gas tank so you can get a better view on the front suspension pan. It's the stuff you can't see that will get you...

+1