How to clean up after a car fire | Project Toyota MR2 V6

Having stripped the engine compartment of our carbecued 1991 Toyota MR2 Turbo in preparation for its forthcoming V6 swap, we could finally take stock of the extent of the fire damage and how it would affect our 2GR-FE install.

[How to react when your car catches fire]

The good news: It’s not too bad once you get things cleaned up. There’s lots of soot and a tiny bit of charred paint, but overall the fire damage was fairly limited.

The firewall insulation seems to have taken the worst of it. It came out in charred, hairy hunks, but left mostly clean metal behind.

Most of the damage is limited to soot and some minor char. We need a way to effectively clean off things, but we don’t need to completely strip the engine bay to bare metal.

We’ve also got a clearer look at the fact that our car did some time in New Jersey before it came to Florida–fairly common story when you think about it–in that there’s some surface rust plus some corrosion creeping through around bolt holes and bosses. Nothing structural, luckily, just typical northern car crust.

We also have fire damage to the two main wire harness trunks coming into the engine bay. One comes through behind the driver’s seat and a smaller one on the passenger side.

We estimate that about half of the wires are probably damaged, but our plan is just to chop the burned section from each harness before spending a few nights splicing in replacement wires. It’s the only way to know for sure that everything is fixed properly. Ultimately, we’d rather do 40 splices at once instead of 15, then another five, then another three ….

We’ll also need to do some wiring, as these two runs of body harness felt the heat. We’ll simply cut and splice in new sections of harness to replace the damaged sections.

Then there’s the matter of the physical condition of the engine bay. As we said before, there’s lots of soot, fire powder and general char, but no major damage. So we first needed a way to clean the soot and prep the surface.

Here’s a spot of unibody prior to blasting: Lots of soot, fire powder and some charred paint.

Our solution was soda blasting. No, we’re not hosing down the engine bay with Mt. Dew Code Red but rather using baking soda–better known as sodium bicarbonate to scientists and nerds–to clean and prep the surface for repainting.

Baking soda blasting is similar to any other abrasive blasting, whether you’re using silica glass beads or ground-up walnut shells, except that baking soda is exceedingly mild and easy on the substrate. It also uses a relatively safe, inexpensive, water soluble, biodegradable media.

Soda blasting is usually done in the 90-100psi range, and the equipment is fairly affordable. We started off with a cheap $30 handheld blasting gun from Amazon, but we like the concept so well that we’ll probably upgrade to a 15-pound system from Eastwood or Harbor Freight for around $150 at some point.

This $30 blasting gun is great for small spots, and convinced us enough in the process that we’ll probably upgrade to a larger hopper.

We got a 50-pound bag of soda from Harbor Freight for $50, and we love its capacity to remove loose material without etching the substrate like traditional abrasive media. Sodium bicarbonate is highly friable–the particles basically explode when they hit the surface of whatever you’re blasting–so the 100-to-200-micron particles typically used in the process become an even finer, powdery dust once deployed.

Soda blasting media is inexpensive, which is good because it’s single-use only. Clean your engine bay, or do some Tony Montana cosplay, then simply hose it away.

The soda erases the soot from the surface like you’re using real-life Photoshop, and leaves behind a surface that’s suitable for painting after it’s been cleaned.

The soda will not embed itself in the surface, however, so after-blast paint prep is fairly simple. It’s also pretty good at removing surface rust and light scale, as well as the general years of grime that build up on the painted surface inside an engine bay.

While it leaves good, cured paint in place, it will remove flaking paint fairly nicely. It’s actually a great way to determine exactly where your paint is and isn’t sticking to the surface, helping you determine where your restoration work needs to start.

As for safety, the blast media itself is technically non-toxic, but it is a fine particulate. And while the media may not be toxic itself, that doesn’t mean what you’re blasting off isn’t. So we recommend eye protection for sure, and dust protection for your lungs at a minimum, with an actual filtered respirator being preferable.

After a couple hours of soda party, we’ll be ready for a new finish inside our engine bay. Then it will be time to rewire and start putting everything back together.

After a quick blast with sodium bicarbonate, the soot is gone, the loose paint is cleared, and even the light scale is blasted off. This area is ready for a fresh finish.

We haven’t yet decided on a final finish for the engine bay, but we’re leaning toward something common–so something from a hardware store and not a specialty paint store so touchups are just a Lowe’s away. We’re not there yet, though, and suggestions for appropriate finishes are welcome.

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