Justin_K

I have a 1995 240sx and when the weather started to cool down (below 40) it started smoking. It only smokes at night (when it cools down) and gets worse as car gets warmer. It's hard to tell what color it is since it only happens after sunset but it looks white (no blue). At idle it evaporates quickly, when revved quickly a large puff comes out, and when the rev is held out at ~3500 it smokes but not as bad as quick rev. I've smelled it and it doesn't have a sweet or gas smell. The car also drips out the exhaust pipe and on my finger has some black residue.

Thanks for any help,
Justin_K

emoximuu

lol its the moisture in your exhaust kinda like "seeing your breath"

Justin_K

Wow, 16 minutes and I already have a reply. It seems like a lot of smoke for it to be moisture. And it doesn't go away after it's warmed up. I suppose you could be right though. I just thought if it was moisture it would go away.

Roastem

after the car is warmed up are you trailing smoke behind you that you can see in the mirror or are you parked and hanging out the door of your car to see the smoke.

A little smoke on accel in cold weather is ok and normal... kinda liek when you exhale in cold weather... the moisture from yoru lungs condensates when it hits cold air .... and your already warmed up...J/K.

If it s alot then you may wanna look at soem other stuff but it sounds just liek cold weather gotcha thinkin too hard.

Joel SX

Here's whats happening as I see it. Because its cold weather, the air gets denser, and hold more air in the same space. It also holds water, but now it more liquid in the air than before, so there's also more water, just like air. when you start the car up, believe me, most of your gas is beign trown out to the cat, and even the cat can't burn it cuz its so cold. If you put your hand on the piston, It would feel cold, since the whole engine is metal and metal transmits heat very quickly. So when cold air goes in, it doesn't burn right,and the litle heat is given to warm the pisto nwalls and what not. as it gets warmer, all the air is being burnt along with fuel. your engine computer (if its OBDII) will notice the drop in temperature and add more fuel. thus now we got a very dense air with water and fuel. when it burns, all the water in the air evaporates, but it can't spand well, then it goes to the cat. remeber that un-burn't gas? well not its evaporated *** well. when we burn gas, there's water vapor released. So now we got: water vapor from air, compresed; water vapor from engine combustion; water vapor from emision control materials inside the cat. All of it compresed. Now when this hot air goes out, it expands and combines with the super cool air, thus all the water i nthe air that was compresed ( lots of it) condenses very quickly. So quickly that it turns into water droplets. Because you end of the exaust is so far from the engine, it cools and water condenses here too (remember how metal transmit heat good?) and not only until it pools on the mufler or whatever you got is that the water will come out forced by air. Sometimes, when you turn off the car, the remaining air has to go trough many holesand things i nthe exaust and it condensates the water here, so when you turn on your car, you can see more water coming out than when you're runign it. sometimes in tablespoons or more. this is why exaust systems are not eternal, unless you got stainless steel. And even that rust too. So remember : there's tons of water in your engine and everywhere. Water is normal, up to a point ( you don't want coolant in your engine combustion chamber :P ). Enjoy the could of white smoke while it last. Its a remaider of how mcuh gases we put into the atmosphere and why takign out the cat for 1 miserable hp is not worth it. Now try to smell the smoke from afar. If you can smell the smell of burnign oil, like the one from a weed wacker, from about 3 or 4 feet away ( no wind of course) then transmission oil is leaking trough your Vacum line that goes to your transmission, if automatic. Other than that, it could be like I said coolant. But this is rare, and by the symptoms I don't beleive it is. check your coolant to be clean and green. if oil or blakc apears, flush it, and don't trow it down the road to the lake: respect the enviroment) let it dry by itself. then fill it up with more water, run it and this one you can let go anywhere. then re-fill. If more oil and black stuff comes out, you got a blown gasket letting water go int othe combustion chamber, and will need replacement. I hope all that information helps!!

PS: I guess going to college and taking physics with calculous really helps to understand thermodynamics :P. Yes many typos

twofotisx

wow, like i can imagine that you tried hard there but I can't even read that crap. Or maybe just one long copy/pasted sarcastic post?

JoelSX, what the hell are you smoking?? or have you just been on AOL too long...

Also thermodynamics has nothing to do with which color smoke is coming from the engine. Thermo is the transfer and movement of heat energy. Not a 240sx possibly having a some coolant get into the engine. Lay off the crack.

Justin_K

It is an Auto and I can smell the oil smell as described. I just got the car not long ago, all new to the 240 and when I checked the tranny fluid it is very high. I checked it when cold and it came all the way onto the wire. I'll check hot later and put a new post up about this because a new sound from under the car (tranny?) appeared. Thanks for the help.

Justin_K

Joel SX

Twofotisx. Like you said, thermodynamics is the transfer and movement of thermal energy. Heat is thermal energy. Heat tranfers from hot exaust air trough Headers and pipes to the cold outside air. Therefore: heat transfer, movement: Thermodynamics. Heat moves from places, and its moved too. But cold air doesn't move. Cold doesn't exist. Cold is the absence of heat. Heat is energy, so there can't be anti-energy.

I'm sorry you're too stupid and un-civilized to understand. Like he said, the smoke is white, but he wasn't sure if it was smoke. I made a huge explanation of why it happends. I'm not on AOL or Crack, but maybe since you've been, you know how people act under these circumstances, so it might sound very familiar to you. If you think its a re-post (copy paste) go do search and provide a link that tells all the information 94% exactly as I did, and post a link. We'll let the others decide, so that its fair. Otherwise, I would recomend not posting negative post since it just makes you look dum, takes space, bandwith and time from those who are seekign answer.

And after doing my research on the repair amnual and Alldata Mechanical database, and by the symptoms of the car, I came to the conclusion that its Coolant
Cooland= white smoke (water vapor+funny smell)
blue=oil
black=rich fuel mixture

Since its water vapor, when you accelerate, the pump goes faster, and more water is leaked into the Combustion Chamber. Since its friking cold, Water vapor likes to condensate, and since ther'es so much in the exhaust fumes, it looks like a cloud that disperses quickly. this is a head gasket problem. Its blown and will need replacement. not more than 120$ if you get good price. Now, there's a posibility that you have a "cracked, blown, deformed, warped, busted" cilinder head. This means that B/c you gasket is not in the right shape ( too many years of heat, go back to cold, heat, etc.) coolant leaks trough into your cilinder head, thus the smoke, evaporation etc. The mechanic will change the head gasket, and have the head polished flat or sealed or both at a machine shop. Worst case scenario: New head+gasket.

This is why it is important to warm up the engines in cold weather. Warming up allows the engine to run at minimum power, with very low stress, and allows for slowly and even heat distribution along the engine block. It also allows the oil to warm up, which helps reduce friction damage, pre-mature engine wear. Don't buy coolant leak stopers, they won't help here, just repair it as quicky as posible. Good luck!!

And unlike other people, I do know what I'm talking about

nsn240

its just the hotter, more moist air coming from the engine... if it smells sweet, like oil, or like gas you have a problem

dont worry, my car pours out that "fog" when its cold