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  1. #1
    Ultimo Miembro FantŠstico Gigantesco ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD's Avatar
    ChrisD has been to an official Ogopogo Meet! ChrisD has donated to the forums! ChrisD helped get Luni's MR2 back on the road! ChrisD helped bring Chaos back to the Dragon ChrisD helped KM replace his 5-year-old clutch.

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    Default FAQ's: exhaust smoke by LoKi

    By LoKi

    Quote Originally Posted by LoKi
    hey guys... its the time of year for cars to be having problems. its just murphy's law i suppose. harsher weather for most of us, and those of us with older cars are having trouble sleeping at night (thank god my 2k celica is in the garage sleeping.. but my civic is a 92... not quite old.. but getting there.. ).

    so here is some info about exhaust smokes that i grabbed off the net. if you have anything you'd like to add, or any personal experiences you'd like to relate, post em here.

    i've noticed lately a sweet smell from the exhaust of my civic. but i can't tell if its smoking or not. well.. i guess its not. cuz smoke doesn't dissapate like steam does from the exhaust pipe in the -9 deg.C weather.. brrrr!!

    but it got me thinking.. in the event anyone does notice smoke in the pipe.. its never a good sign..

    Black smoke is raw gasoline burning. A rich condition can be the cause by a heavy or mis adjusted float, a choke stuck shut, a bad oxygen sensor, a bad map sensor, a bad fuel pressure regulator, a plugged up air filter or a bad injector. Typically, if you only get black smoke first thing in the morning, it has to do with the choke or the fuel enrichment portion of your fuel injection system. If you get black smoke all the time, get it fixed NOW. If you donít, you run the risk of wiping out the catalytic convertor and doubling your repair bill.

    Blue smoke is oil burning. The tailpipe will either smoke all the time or just once, first thing in the morning. If you get blue smoke all the time, that is a sign of impeding doom. That is the first sign of the beginning of the end. Broken rings, bad pistons, damaged cylinder walls, all high dollar items.

    On the other hand, if all you get is a puff or two first thing in the morning and never again throughout the day, then your problem is probably bad value guides or value guide seals. It will cost between $350-800 to replace the seals, $750-1,500 to replace the guides and seals. I always tell my customers, wait until you begin to see other symptoms of this oil usage. Wait until you start fouling plugs, wait until the oil consumption is greater than one quart every 1,000 miles. And never assume that seals alone will totally fix this problem, if the engine has 100k miles plus.

    Grey smoke can really be black or blue. You can usually tell which is it by the smell or by matching other symptoms you have to the color of the smoke is easier. Others will say blue is blue and all other is really grey to black and I would agree.

    White smoke is either the transmission shift modulator is bad and allowing the engine to suck and burn transmission fluid (repair costs under $100) or itís really, really bad. White smoke could also be coolant or antifreeze that is either leaking, or being forced into the combustion chambers and being burned. The exhaust will look wet and have a sweet smell to it. A bad head gasket (75% of the time), a broken head (15% of the time) or a broken cylinder wall (10% of the time) will be the reason your engine is burning coolant or antifreeze. The repairs start at $400 and go to $4,000.

    Quote Originally Posted by LoKi
    this here is a 'how to check for a bad head gasket' type thing i found on the net as well...


    3. The engine is consuming the coolant. This is created by a bad head gasket or a broken engine block and has some very specific symptoms. And water in the oil is only one of the many symptoms we look for. For the record, a head gasket can be bad and we wonít find a drop of coolant in the oil Ďcause all the coolant that is leaking into the cylinder is being sent out the exhaust and is not going into the engine oil system.

    The first thing you may notice is the engine misses when it is restarted after it has sat for between 15 minutes up to 3 or more hours. When the engine is shut off, coolant is forced by pressure into one of the cylinders and when the engine is restarted, the coolant causes a miss until all the coolant is forced out into the exhaust. You may or may not see steam come from the tailpipe. STEAM FROM THE TAILPIPE ALONE IS NEVER ENOUGH TO CONDEMN THE HEAD GASKET. All cars have to deal with moisture in the exhaust on a cold morning start up, so steam from the tailpipe is very normal as the catalytic converter heats up and boils the water sent to it by the cold engine.

    There are three tests we use to find a bad head gasket or being more precise, a coolant leak into the combustion chamber.

    1. We use a dye and suck the fumes out of the radiator and run them through this blue dye. If the dye turns yellow, that means the presence of exhaust gases in the cooling system.

    I must tell you I donít think much of this test. The positive results of this test mean nothing ALL BY THEMSELVES.

    2. Apply pressure to the cooling system and watch the pressure gauge as you rev the engine. If the pressure rises quickly, that is a very good indication there is a combustion leak.

    3. Fill the cooling system up with coolant, drive the engine till it gets good and warm. Park the car and shut off the engine. Make sure the upper hose is stiff and hard which indicates good cooling system pressure. Apply external pressure if needed via a cooling system pressure pump. After allowing the engine to cool for about 30 minutes, pull the plugs and crank the engine over. If any coolant comes blasting out of any cylinder spark plug hole, there is no doubt the engine has a combustion leak.
    Quote Originally Posted by LoKi
    and an article i found on oil consumption in engines.. which also talks about the "puff of blue smoke in the morning" problem... [Wink]


    Oil consumption & blowby problems.
    Whenever you are looking for an oil consumption problem, you start by changing the oil, logging the miles and checking the dipstick weekly. DO NOT add oil unless the level is AT OR BELOW the add mark. All engines use oil, some more than others and 90% of all engines are MORE than a quart low at 3k miles. That would mean that at around 2000-2500 miles, they were a quart low.

    The MINIMUM level of usage is a quart every 750 miles, according to all the car makers. While that would be totally unacceptable for a new car, that is where we start planning the overhaul of an older engine.

    Once you verify that you are using more than a quart every 1500 miles or less and you know you don't have an external oil leak, you would begin by pulling the spark plugs which will tell you which cylinder(s) is burning the oil. By performing a leak down test and a wet / dry test will then tell you if it is a piston ring or valve guide or seal problem. If your oil level is still above the add mark at 1500-2000 miles, everything is fine.

    Piston ring problem --- No choice but to either wait it out or fix it by overhauling or replacing the engine. Cost will vary between $1500-4000 depending on the engine size.

    Valve guides or seals --- IF you have a puff of blue or grey smoke from the tailpipe in the morning, IF you don't have any other smoke throughout the day, IF you have a very minor oil usage problem, IF you have between 60k to 100k on the old clock (speedo), all of that points to bad valve guides or seals. My advice is never fix this very expensive repair UNTIL you begin to use a lot of oil AND oil foul your spark plugs. Often you will have this "puff of blue or grey smoke first thing in the morning and never again during the day" for years before you foul your first spark plug.

    You see, no one can be sure if your oil consumption problems are because of bad valve guides or seals. The seals typically cost $200-500 depending on the engine but to pull the heads and rebuild them will cost $850-1500. So what happens if they think it's bad seals and do all the work to replace them, and that doesn't fix your oil consumption problem? All of that money was wasted and you still have the same problem.

    Blowby Problems

    Excessive blowby is often seen as oil in the air cleaner. The PCV or positive crankcase ventilation systems job is to vacuum the pressure out of the engine that is created by combustion leaking past the rings. When there is more pressure inside the engine than the PCV can handle, the excess pressure and oil mist is forced up the fresh air intake hose and into the air filter area.

    Typically the car owners will first see their air filter soaked in oil and wonder how the oil got there. When this happens, the question is "Is there something wrong with the PCV system or is it being overcome by excessive internal pressure created by a bad piston or by bad rings?". Because anytime you have blowby problems, it's going to be related to one or the other.

    On the PCV system, the vacuum port can get clogged with carbon, the rubber vacuum hose that goes to the PCV can collapse or the PCV can be bad. All will stop the vacuuming of the crankcase and allow excessive blowby. So always start at the vacuum port and work your way to the PCV valve.

    If the PCV is fine, then your blowby problem will be because of a bad piston or bad piston rings. You can use a thicker oil like a straight 30 weight or 40 weight to slow down the oil usage and blowby but the best repair would always be to fix the combustion leak, which means overhaul or replace the engine.
    Quote Originally Posted by LoKi
    and since you can never have too much info..


    has some good info about what to do should you see smoke of anykind in the tailpipe..
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  2. #2
    Ultimo Miembro FantŠstico Gigantesco Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean has a brilliant future Sean's Avatar
    Sean has donated to the forums! Sean helped get Luni's MR2 back on the road! Sean helped bring Chaos back to the Dragon Sean helped KM replace his 5-year-old clutch.

    Join Date
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    Didnt see it in there, but sythentic oil, also burns white

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    Turbo 1990 Celica T3/T4 57 trim
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  3. #3


    did i post this? LMAO. damn what a long time ago...

    but yea synth burns white as well, but smells like oil burnin'... not coolant..
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