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Automotive My engine was smoking the other day

  1. Jan 12, 2013 #1
    I was stopped at a red light and there was some smoke coming out of the engine compartment of my car.

    There is also a slight burning smell.

    This is definitely not good. If you are a mechanic or automotive engineer, what is your take on this?
  2. jcsd
  3. Jan 12, 2013 #2
    did you check fluid levels of radiator?
    Last edited by a moderator: Jan 15, 2013
  4. Jan 12, 2013 #3
    Well the first thing to do is stop driving it and look under the bonnet.

    1. What colour is the smoke? And where exactly is it coming from?
    2. What are all your vital fluid levels like?

    Are there any other symptoms?
  5. Jan 12, 2013 #4


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    If the smoke smells like oil, that could be a sign that a head gasket needs replacing. If the smoke is light-colored and slightly "sweet", that could be a sign of leaking coolant. You've got to look at the engine to see what's up. Leaking coolant could be as simple and cheap-to-fix as a loose or split hose. Much better than a head gasket or (worse!) a cracked head.
  6. Jan 12, 2013 #5
    Along with the smoke, there is a very pungent burning smell. I had to pull of the road and check my car because I thought that it was on fire.
    Last edited: Jan 12, 2013
  7. Jan 12, 2013 #6


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    Did you figure out where the "smoke" was coming from? That's pretty critical if you want help.
  8. Jan 12, 2013 #7

    jim hardy

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    Mighty skimpy observations from which to diagnose.

    Pungent smell? Smoke? No other symptoms?
    My guess - brake fire. Flex hose between a front caliper and chassis is deteriorated or damaged. When that happens they can allow flow in only one direction. That brake cannot release so it gets extremely hot.
    You might have noticed a pull to one side for a while before the smoke..
    If you've had brake work recenty - it is not difficult to twist that hose when re-installing calipers and cause that situation.
  9. Jan 13, 2013 #8

    Ranger Mike

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    A quick inventory of common fluids that could be in close proximity to the exhaust manifold and exhaust pipe is in order.
    The exhaust manifold at the cylinder head would have 900 degrees F and dip to 200 F at the end of the exhaust pipe. The entire exhaust system would be hot enough to evaporate fluids.

    Brake fluid- if the car is old enough the steel brake lines may have rusted. The result would be loss of brake pedal firmness and would be obvious...In older cars that had only one master cylinder, not t he dual master cylinder present since 1965...total brake failure would be obvious. Clutch master cylinder fluid - if car has manual transmission this is a possibility and soft or no clutch pedal would be obvious.

    Automatic transmission fluid – there are numerous rubber hoses that connect to various vacuum modules on the automatic transmission and this is a good possibility.

    Clutch smoke – possibility – if the engine has a very leaky rear main seal on the crank shaft, engine oil could seep and eventually cover the flywheel and pressure plate assembly and get so bad the clutch slips and causes the smoke...engine oil level should be checked..slipping clutch would be obvious.

    Antifreeze leak – many rubber hoses conduct the antifreeze from the radiator to the engine block and heater core. A check of the antifreeze fluid level would show this. A blown cylinder head gasket would cause smoke. Possible cracked cylinder head or cracked engine block .but most unlikely. Most common fault is radiator and heater hoses...Use your hand and squeeze the hose with you hand and if your thumb nail pushes in the hose easily, if the hose feels spongy and flimsy...time to change them.

    Oil leak from valve covers, intake manifold gaskets- could be and you should be able to see the smoke.
    Power steering fluid- you have rubber hoses carrying fluid to the pump and this may leak and smell but usually not mounted in close proximity to exhaust on newer cars..check the fluid level.
    Windshield washer fluid- I have seen stranger things but it is a possibility.

    Air conditioner could seize and the belts could smoke on a frozen non moving pulley..high pitched noise ( like ex wife complaining about alimony) would be very apparent.

    Battery - check to see if batttery acid has leaked due to cracks in battery case..highly unlikely. could happen.

    Dead cat in engine room...Once found that a cat had crawled in the engine compartment to stay warm at night. The next morning when I started the car, the engine fan blade caused sever cat-stophic ( sorry ..had to say it) failure of cat brain housing. Hey, I can’t make this stuff up.
  10. Jan 15, 2013 #9
    I took my car to the shop and the mechanic told me that large volumes of motor oil was leaking into the cylinders and burning.

    This explains the oily burning smell and the black smoke coming from the exhaust.

    Also, my head gasket was severely cracked.
  11. Jan 15, 2013 #10
    rangermike, pretty solid explanation. I don't think most of those would cause a significant amount of smoke to rise from the hood like he was saying. While possible, it would be extremely rare, and problems in subsystems including powersteering, clutch and the brakes system would fail long before all that fluid could be released (on a hot manifold).

    Chances are likely a major oil leak, or blown head gasket. In less common cases, a ruptured fuel line.
  12. Jan 15, 2013 #11
    Mechanic said that severely damaged head gasket and cracked cylinder was leaking oil into the the combustion chamber as well as onto the hot engine manifold.
  13. Jan 15, 2013 #12


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    If it's that bad, personally I wouldn't bother to repair it. Fit a reconditioned engine. Less labor costs, and less chance of more problems emerging later.

    Or if the entire car wasn't worth much (before you blew the engine), consder just getting a new car.

    The repair shop might try to persuade you otherwise though, because they like "interesting" jobs to do, to relieve the boredom of doing routine servicing!
  14. Jan 15, 2013 #13
    I'll probably just get a new engine.
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