white smoke
 

howdy, im knew to this forum and i just wanted to say hey and ask a question. i know a lot about cars but not about the rotary engine. im looking at buying a 93 rx7. i talked to the guy that owns the car. he put a new engine in it about 4k miles ago. since he put it in, he said that sometimes it blows white smoke from the exhaust for 5-10 seconds then quits. another thing is that he has to put a quart of oil in it about every 150 miles. what is wrong with this engine. he bought the engine from a mazda dealership here in nashville, nelson mazda. he thinks its a bad engine. i dont know what it is, so, whats with this engine?

Is the white smoke for 5-10 seconds on start-up of the car? if so, this is normal. he might have an oil leak at the oil pan or oil cooling lines for the turbos. If it smokes alot while driving it, then it might not be a leak and the motor probly has a bad seal.

Sean

white smoke is normal. if its a cold start, the exhaust would mix with the air outside, making it a smoke white color.

does it dissapear after startup? have you noticed other cars smoking on the road as well?

Sigh......the "white smoke" on startup is called "condensation". As the engine warms up, it burns off the water that condenses inside the intake and exhaust tracts, which exits the exhaust as steam. All cars do this on startup on cold mornings.

As for the "a quart of oil every 150 miles", if that is indeed correct (which, given the owner's apparent lack of overall car knowledge), the car has an external oil leak somewhere. The rotary engine uses up oil by design, so you have to top off the oil once in a while, depending on your driving habits...but not every 150 miles.

How long can condensation steam go on? 5 minutes or 30s? I noticed some water drops blowing through - is this common with condensation steam?

What if you warm up the car (till tailpipe pushes clear), shut it off for 5 min, then start again - bad coolant seals would push white smoke again immediately, but steam wouldn't show up at all since the exhaust is still hot and dry. Correct?

Is there a way to directly test the tailpipe emissions for burnt coolant?

It depends; simply sitting idle warming up the car will take longer. Yes, water drips out the exhaust as the engine warms up.

Unless you were doing this in near-30 degree F ambient temps, I'd say yes.

Your nose. If it's belching out steam every time you start the car when warm, you should be able to smell burnt coolant.

Thanks. This helps me a bit more than 'if it's white, it's coolant seals, but if it's white, it's steam' :D