Would your early car pass the screwdriver test?

[Shaun @ Tru6]

My early suspension refresh turned total restoration couldn't have come at a better time. I cleaned out the motor bay today and what looks like nice, hard, solid factory undercoating is really a dry, brittle nightmare hiding rust and the potential of trapping water under it. I was going to just run some POR15 over the surface, paying attention to some areas where it flaked off. On closer inspection, and some LIGHT scraping with a flathead screwdrive, it just comes off in large flakes, VERY EASILY! I think if I had left this for only a year it would have meant a lot of welding. Now it's just surface rust.

Anyone looking at an early car purchase should fully inspect all underneath surfaces very carefully. BTW this was a CA car all its life.

[Paulporsche]

Good catch!

[rvanderpyl]

I'll soon find out as I pulled the motor yesterday.

[ttweed]

Originally posted by Shaun 84 Targa
On closer inspection, and some LIGHT scraping with a flathead screwdrive, it just comes off in large flakes....

This has been the case with every early car I have ever had, no matter where it spent its life. It's when the screwdriver pokes through the metal that you have a problem! At least the metal is sound in the places you have uncovered.

I use a flat-bladed scraper to lift and remove all the loose coating at the margins of the bare areas, widening them until I get back to bright metal and well-adhered undercoating, then a stiff wire brushing to remove the surface rust, then clean with degreaser, apply the metal prep treatment for 20 minutes, rinse, dry, and apply two coats of POR-15, topped off with new undercoating, and you're probably good to go for another 35-40 years.

TT

[Dantilla]

I got real lucky. Bought my '73 at an auction where I couldn't thoroughly inspect for rust.

Got it home, started taking the interior out, not knowing what I'd find, and there was zero rust. Pretty amazing. Bare metal repaint since then, so I know I'm in good shape for years to come.

[Tom F2]

This much less of a problem on 1970 and later cars, because at least the floor pan and some of the internal panels were zinc coated. The difference is dramatic.

[T77911S]

also check around and under the gas tank and front suspension.

[coldstart]

I just inspected my engine bay in detail (with the motor out) and I couldn't believe how rust free it was.

These are great cars-- nice to see you taking that type of care. Definitely worth it.

[EarlyPorsche]

I too found the area of rust in my early car. The rest was so rust free but when it came to that corner and a hood seal going bad allowing water to not run off the car it rusted the front hump bad.

[berettafan]

Tom thanks for answering my question before i even asked it!

[Todd Simpson]

Shaun-

This is a regular routine for me on my '71. The latest area I treated was the front subframe mounts. Lots of nice undercoating just came off in huge flakes. The front suspension, battery area, rockers, floors and engine compartment all have been checked and treated previously.

Check the *inside* of your torsion tube as well.

[lateapex911]

Tom hit the nail on the head. The other method is to strip it bare, shoot self etching primer on the bare metal, then primer, then color, then undercoat, Or use body shutz intead of undercoat, then color on that.