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Flaming Volvos

We own a deceased 1991 Volvo 240 Station Wagon. Last night, as it was sitting, turned off, in our driveway, it burst into flames. We don’t think the car was Buddhist, and, at any rate, we are a pacifist family, so I don’t think it was a political statement. I have seen several, if not numerous, complaints and videos about Volvos bursting into flames while being driven, but I think this is the first siting of an apparent spontaneous self-immolation. Do you have any idea how this would happen in the real world where there are no possessed cars?

To aid in unraveling this pressing mystery, I should give you all that I know.

0. The car had been driven about seven miles about an hour prior to burning.

1. Just seconds prior to being engulfed in flames, the car was dripping fire, according to police.

2. There was a loud pop (as heard inside our house) and what in retrospect was probably a shock wave rattling our front door.

3. When I looked outside, the first thing I saw was the entire engine compartment on fire, and what appeared to be the oil pan on the driveway below the engine.

My cockamamie idea:

Because I don’t believe that cars sitting at room temperature burst into flames, I think that there was something smoldering while being driven. If the oil was smoldering inside the engine, my guess is that the pop we heard was the oil pan bursting off the bottom of the engine giving the fire lots of oxygen. This is really the “smoldering cigarette in the couch” model. This whole idea hinges on the possibility of oil getting really hot. Is this possible? If so, how?

Many car fires have started this way. Luckily it was in the driveway. I had a friend’s minivan spontaneously burst into flames in the attached garage!

I’ve seen car fires start for some various reasons, like a pin-hole leak in a brake line squirting brake fluid on the exhaust header when the brake was applied, battery to starter cable shorting against the chassis, fuel leaks including leaking injectors, and parking on leaves or dry grass.

Chances are, there was something wrong with the car you were not aware of, like a fuel leak or a chaffed battery cable. Unfortunately, the root cause may never be known. Just be happy no one was hurt and nothing else was damaged.

Oil dripping on the exhaust pipe or manifold, then to the ground, could be what they seen as “dripping fire”

I like your smoldering cigarette theory, but an hour is a long time. Internal fire should have cooled/smothered by then. Even a hot brake should be too cool to start a fire after an hour. I vote for electrical fire from near the starter that burned through a fuel hose, hence the dripping fire.

There was once a body shop fire that did quite a bit of damage that was blamed on my '66 Chevelle self-igniting.

It’s unlikely there’s enough oxygen inside the engine to support any kind of fire, smoldering or otherwise. Oil has to get good and hot to really ignite. You can throw a cigarette into oil (or even gasoline in a lot of cases), and it will just extinguish. I would guess that you had a battery cable shorting to ground, and this ignited a fire that may have burned through a power steering line or trans cooler line, something carrying oil or gas, which then was “dripping fire” Once it got rolling and the oil got really hot in the engine, the pressure buildup may have blown the oil pan off the engine or there may have been a flash fire inside at that point.

Sorry about your car… that had to be pretty disturbing.

Thanks very much. The most frustrating aspect of this event is that the purchase of a Prius had been a response to smelling gas in the Volvo. We have been dealing with a repair shop for years with this car. So, at the same time we purchased the Prius, we had the shop go over the Volvo to see why we smelled gas. They found nothing. We were about to sell the car with a clear conscience. Unfortunately, this fire totaled another of our cars and singed the new Prius. We were very fortunate that my son was not driving at the time. We would have also felt terrible if a purchaser of the car had been injured.

Thanks. You and oblivion give the most convincing models. I’m guessing that it was oil that was burning. Wouldn’t gasoline be more explosive? My son had also guessed at an electrical fire.

My guess is that you had a spark from a wire somewhere as a source of ignition and that it ignited the crankcase fumes somewhere by the valvecover, and that the subsequent combustion (explosion) traveled from the space under the valvecover down the oil return passages and into the crankcase, blowing the pan off. My guess is based on the assumption that blowby on this ol’ Volvo caused the crankcase vapors to be a volatile combination of gas fumes and oil fumes.

A leaky injector seal could have been a contributor…is this oldie Throttle Body Injected? If it’s TBI and the fumes somehow got ignited (again via a spark), the combustion path may even have traveled back through the PCV orafice into the valvecover cavity and down to the crankcase. After all, the real purpose of a PCV valve is to prevent a backfire from traveling this path. An ignition in the throttle body caused by a spark could do the same thing.

Understand that there exists open paths from the cavity under the valvecovers to the crankcase fumes where the oil drains back to the pan after lubing the valvetrain.

You had a gas leak, and on this particular occasion the gas happened to drip on a hot engine or exhaust part and catch fire. I don’t know if the shop that failed to find the leak is legally responsible, but I certainly wouldn’t take any other cars there. You might let the manager or owner know, just to see what happens.