I have a 95 honda civic ex (manual), and it smokes really bad from the exhaust. It's thick white smoke that lingers, and it also burns oil, but when checking the oil, it is not clouded up or milky or anything. I heard white smoke was coolant burning, and usually when oil burns it's darker, but the person I bought it from said he thinks it has bad piston rings, but I was wondering what anybody else thinks it could be. It also has a bad IACV, and it switches up and down a lot while idling, not sure if that has any effect. I will be doing a compression test soon, along with replacing the piston rings, and head gasket replacement. But I would like to know if there are any other diagnostic tests I can do, or if it could be anything else. Any help or comments appreciated, thanks!
If it's white smoke, you can pretty much be guaranteed it is burning coolant. If you smell it and it has that sweet smell to it, be assured that's what it is. Do the compression test, but I doubt its the rings. Like was said in the comments:
- White smoke = coolant
- Blue smoke = oil
- Black smoke = incomplete combustion
The IAC will have nothing to do with whether it's burning oil/coolant or not, but will need to be replaced or most likely cleaned before you put it back together from the head gasket job. While you are replacing the head gasket, ensure you have the head checked to ensure it isn't warped. Also, coolant can leak into a cylinder and burn without it ever getting to the oil. Oil can also get into the coolant without showing traces of coolant in the oil.
You can check the spark plugs as well. When you are burning coolant, you'll find one (or more) of them will be a lot cleaner than the rest of them. When you find the clean one, you'll know which cylinder is getting the coolant.
If you are getting smoke from the exhaust make sure that the positive crank case ventilation valve is not clogged, or short.
The PCV valve is highly essential for the crank case to have ventilation to send the exhaust gases in the crank case out.
I had my friends elantra with a same problem and after the replacement of the pcv valve the smoke is gone.