My S40 caught on fire a few weeks ago and nobody seems to be able to figure out the problem. I was in a snow storm trying to power up a hill. We were doing great when all sorts of warning lights started to come on like the brake and abs. We stopped as soon as we could, since we were making our way up a slick hill, and the car started smoking. When we opened the hood, there was a small fire which got bigger. We used the snow to put it out. After 20 minutes or so the car seemed fine. When we checked the radiator fluid level, it appeared to be completely gone. The only thing visibly damaged due to the fire, was the a plastic cover. I was in an accident (front/engine damage) a few months ago, and we are wondering if the repair shop forgot to put radiator fluid back in or didn't replace something they should have. Does anyone have any suggestions? The car is now at a Volvo dealer, who also has no idea how/what happened. They are waiting for a special engineer to come and check it out. Help, I love my car and want it back to normal!!

IT isn't likely that the shop forgot to refill the coolant, unless that was the very first few minutes that you had the car back from the shop. I'm guessing the radiator was replaced (they would HAVE to refill the coolant or it would've negatively impacted the car already). Otherwise you'd have noticed it before, or the car would have overheated. In other words, there would have been some sort of indication. If it was only 1/2 full, it could've been at normal temp in cooler weather, but once you worked the car out, it heated up too much.

Also, usually shops will run a car for an hour or so after it's been hit in the front, to make sure that it idles right, the fans come on, and it stays cool. It's likely that they did that, at least to some degree.

Possibly, working hard in the snowstorm, caused a big heat buildup. I don't know how bad the snow was, but if it impeded ventilation to the engine compartment, or if there was excessive wheelspin involved, there might have been high levels of heat generated underhood.

Other than that, if there was wiring work done, the current draw from one of the underhood accessories might have been enough to set it off. Additionally, a ground bus might not be well connected and could've caused resistance problems. That is a very easy thing to check when repairing a crash, but it's something that could build corrosion or come undone at a later time. Pinched wires, etc., are all possibilities. Add to all these things, the potential for moisture to enter places under the hood in heavy snow.

These are just some ideas.
--
Chris Herbst, in Wisconsin.

Your electric fan is at the front of the car and draws a lot of
current. That is a possible cause of a fire if not correctly
repaired.

Did you actually see flames?

If the repair shop forgot the coolant I doubt you would have
gotton very far once you left the shop.

The main cause of engine fires is oil on the exhaust pipes or cat. conv. and it usually happens with a very hot engine. The oil might have been due to previous work, something leaking.