rust piles around the FiatX1/9

Fiat X1/9 – Rust Hunt and Treatment

6 min read

Having recovered the Fiat X1/9 and given it a quick inspection and wash, it was time to hunt the rust and give it some treatment. So far this project car is proving to be in fantastic condition for the money, a true bargain. The seller was upfront about some of the cosmetic issues but before shipping halfway around the world, it was time to see just how good this Fiat X1/9 is under the surface.

Underside Rust Hunt

I have to be honest, I have a pretty low expectation for Fiat corrosion resistance. Most of the Fiat’s I have worked on have involved tackling rust issues, so I’m already biased. So with the car up on 4 of Halfords finest axle stands, I slid under the X1/9 with screwdriver and wire brush to hand.

Rust on underside of drivers footwell
Rust on underside of drivers footwell

And within seconds, the rust started to show its self. This is the underside of the driver’s footwell. Though the 30mm diameter hole, you can actually see the carpet in the cabin. Much of the corrosion was hidden under the stone chip, moisture having crept along between the steel and impermeable layer.

The corrosion here looks pretty aggressive, even terminal, but this is a surprisingly thick piece of steel. The hole aside, the rest of the rust is surface corrosion with no delamination or flaking. It just needs a bit of rubbing back and treating, perhaps painting and new stone chip in the long run.

Treating the Surface Rust With Dinitrol

On the underside, this was the only rust hole I found, which for a 30+ year old car was really surprising. Almost disappointing. There were other small patches of surface rust, which were all treated in the same way.

Once I’ve scraped off the underseal past the edges of the surface rust, I apply the wire brush to remove the worst of the oxidised metal. There are a huge array of corrosion preventers and converters available on the market, and I’ve used many. They generally all use the same chemicals to ‘convert’ the rust, but the results vary.

Dinitrol Converust Epoxy
Dinitrol Converust Epoxy

For around 6 years I’ve been a convert to the Dinitrol Converust RC 900 epoxy spray. Like most products, it converts the rust and turns it black. however, with this being an epoxy it also seals the area robustly. It will be perfect for the Fiat X1/9 rust treatment.

I usually apply three coats, and as the can says, it can then be overpainted. It needs to go on dry, I will often use a heat gun, otherwise, the pressurised can make it easy to apply. It’s not the cheapest solution, in fact, its not the cheapest Dinitrol product, but it’s so convenient I highly recommend having a can on the shelf.

Boot Rust and Treatment

The MOT had made mention of rust around the engine bay and needed tracking down as it wasn’t immediately obvious. Stripping out the carpets in the boot, the rust was still not immediately apparent.

Boot with carpets removed
Boot with carpets removed

Taking out the boot floor and the glass insulation underneath started to reveal more oxidised steel.

Rust starting to become apparent
Rust starting to become apparent

The cause of the rust or at least the location the water was getting in was easily located. Removing the rubber seal revealed the first eyebrow-raising rust,

Rotten boot seal leading to major corrosion
Rotten boot seal leading to major corrosion

The top edge of the boot, hidden by the carpet trim, is heavily corroded. The lip on which the trim should sit was missing over more than 20cm. This has been letting in water for a long time with the carpet and glass insulation holding more than 2 litres of water when drained.

Preparing the rust area for treatment
Preparing the rust area for treatment

After some wire brushing and the true impact of the missing lip starts to be revealed. While looking more like a lace curtain than a piece of steel, the corrosion here is perfectly repairable. To let in a repair plate with the 20mm x 10mm lip would be a straight forward repair for even the hobby welder. However, the water has been getting in here and pooling in one place!

Underside of the boot floor, beyond rust treatment
Underside of the boot floor, beyond rust treatment

Getting under the car the location where the water was getting out becomes apparent. Directly above the exhaust hanger, the body panel is more hole than steel.

This is by far the worst corrosion on the car and is going to need some rectification. Most of the rust is contained to a single panel, so the repair is straight forward. It might mean taking the engine out, but fortunately, that’s not a huge task on the Fiat X1/9.

The Known Rust

The seller was open and honest about body corrosion, even sending decent pictures. As a result, we knew about the surface rust around the rear end and around the windscreen.

Rear end body corrosion
Rear end body corrosion

Above is an example of this corrosion. The rear valance will need replacing and the poorly fitting windscreen will need replacing. Reassuringly the description of the rust we received before purchase matches up with what we’ve got. Most needs treating and repainting, with some needing welded repairs. All manageable.

Clearing Drain Paths

One thing that did become obvious while on the hunt for rust, is that some of the drain channels were not preforming correctly. Fiat clearly paid quite a bit of attention to the drain paths and water flow while engineering the car. It’s much better than designs ten years newer with good-sized paths for water to flow.

Fiat X1/9 rear drain hose blocked
Fiat X1/9 rear drain hose blocked

While the drain design may be good, they still need some management. The drain path down the side of the engine back was full of leaves and soil. Probably not helped by the plastic tube through the engine bay being crushed. An airline, pokey stick and straightening the drain hose soon sorted soon had the water flowing. The rest of the main body drain paths were also checked and debris removed.

Decision Time for Exporting

With, hopefully, the absolute worst now known about the car, it was crunch time. Having hunted down the rust on the Fiat X1/9 and applied some treatment, was it still worth exporting?


This is not a concourse car and needs some investment, the initial purchase price reflected this. The bodywork will need some attention and possibly repainting. On the other hand, this Fiat X1/9 example is what I would consider ‘honest’. It is free of other owners bodge repairs and shows no signs of impact damage. Its generally free from rust given its age and requires far less work than its final value will reflect, which is very unusual. Perhaps most importantly, it ticks all the boxes in terms of spec and age.

So with the decision of both the heart and finance saying keep going, the next step will be to get it ready for export.

M

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