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We currently had a new turbo put into a 2000 Volvo S40, 110k miles. Initially, the car would smoke when accelerating hard with the new turbo. After a few weeks the smoke never occured again and the car functioned normally. Than, the car stalled at a stop sign and as it was being pushed to a safe location, the engine caught fire. The fire was put out with an extinguisher and the insulation that lined the hood (?) was burnt through. I am wondering if any of this could be because of improperly installed turbo by a mechanic or something due to the age of the vehicle. The volvo still runs, though it sounds aweful. It revs irradically.Locatios of note.

  • These could be related to a new turbo if it was sized differently from the old one and the ECU wasn't correctly reflashed. It's hard to say definitively, though – Hari Ganti Apr 18 '18 at 17:48
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    Most turbos have an oil supply line and a return line, it is possible the oil connection(s) to the turbo leaked oil onto the hot turbo or exhaust and started the fire. – Moab Apr 18 '18 at 18:54
  • @HariGanti How exactly would a firmware issue or turbo sizing lead to a fire? You could get predetonation if the turbo is pushing more air than the injectors can keep up with, or if the injectors are replaced with the wrong size and the ECU isn't updated to reflect the change, but I have trouble seeing how anything related to a properly-installed turbo, even if it's not exactly OEM spec, could lead to a fire. – 3Dave Apr 18 '18 at 19:19
  • @DavidLively Sorry, the fire is a mystery to me. It might be due to a combination of factors, but I don't know. My comment was more about the stalling and erratic idle. This is also why I didn't post a full answer. – Hari Ganti Apr 19 '18 at 17:57
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As @Moab said in his comment, an oil leak from the turbo supply or return line could be the cause of the fire. Oil is nicely combustible, and since your turbo a) gets very, very hot, and b) is right on top of the exhaust manifold, a leak is in the perfect place to catch fire.

If the turbo issue has not been corrected, you may have another fire soon. Fix it before driving the car. You do not want to be trapped in a car going 70MPH when it bursts into flames.

The fire could have harmed any number of things under the hood that can cause the erratic engine behavior. Look at your wiring harness, specifically the lines going to the O2 sensors, ignition coils and other sensors (IAT, MAP and/or MAF, etc.) Look at any plastic parts that may have melted. Check your battery cables (and others) to see if the insulation was damaged, as that can lead to a short. If the insulation is damaged near a grounded part of the engine or frame, and the bare wire exposed due to missing insulation touches it, odd things will happen.

Check all your vacuum lines. A vacuum leak will make the engine unhappy.

Depending on how hot it got under the hood, you could have warped or cracked the head and/or block. However, if that happened, I'd expect the car to be a smoldering pile of slag, not just running rough.

Another option: get the shop that installed the turbo to pay to replace the whole engine and harness. (Admittedly, given your experience so far, I'm not sure I'd let them do the work.) If they're at all reputable, they should cover this.

  • Thanks, I am having the same auto repair guys take a look. I'm not sure if it is the turbo (I have limited repair experience). I just wanted to know what could have caused the fire given that the fire started relatively soon after the installation of the turbo. Do you think I should have another mechanic look for the cause before I take it to he original mechanics? Thanks again. – Hoolz Apr 18 '18 at 19:41
  • @Hoolz Yes, if you can easily have someone qualified take a look first, do so. And, take pictures. I don't believe in coincidence - it's very, very rare that a repair, followed quickly by a catastrophic failure like this, are unrelated. Also, do you have comprehensive insurance? If so, this may be covered. (I know a guy who had a puff of smoke due to a wiring issue with a stereo installation, which fried the wiring harness - his car was declared a total loss and covered by the insurer.) – 3Dave Apr 18 '18 at 19:43
  • Unfortunatly, my insurance doesn't cover it. I'm going to take a look for all those items you mention to see if I can find the location of the fire. At least to the best of my abilities. I am a DIY kinda guy, but my knowledge is limited with engines. – Hoolz Apr 18 '18 at 19:49
  • @Hoolz If you can't easily determine a single cause, my advice would be to either ditch the car, or replace the entire engine, with harness, at once. Fire-inspired heat melts plastic. There is a ton of important plastic - sensors, etc. - under the hood, and tracking all of this down could be a massive timesink with no end. – 3Dave Apr 19 '18 at 23:33

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