Black soot in exhaust. Normal?

[Lantanafrs2]

My 13 burned oil originally but after new long block was installed in 14 oil consumption has been nil

[EAGLE5]

These cars are far from repair nightmares. Your fears are unfounded.

[ermax]

Originally Posted by omadab

So would you say it is because of oil dilution?

No, cold starts go through a rich phase in an effort to heat the cats as fast as possible. This phase tends to put out more crap.

Originally Posted by omadab

its powder. What do you mean by "open loop a lot"

Closed loop is where the car monitors the O2 sensor to determine how much fuel to use. When you are at all aggressive on the throttle it goes into open loop mode where it no longer uses the O2 sensor to meter the fuel and then resorts to a lookup table to determine how much fuel to use. In OL mode the car can sometimes run more rich. If I recall the 2017+ runs exclusively in CL mode though.

If it isn't wet or oily I wouldn't be concerned.

[MCTeeJ]

Every oil change I've done on my car in my almost 4 years of ownership the oil has always smelled a tad like fuel. I had a Blackstone analysis done on it and they said I don't have any fuel dilution, despite the smell. I wouldn't worry about it.

[humfrz]

Originally Posted by omadab

Hello people,
I am currently in the market for a BRZ. I have been looking around and noticed some cars have black soot in the exhaust and that the oil smells like gasoline. To me, it seems that the car is running rich and that either there is a leaking fuel injector or the piston rings are worn. I just wanted to know if this is normal in boxer engines or if the piston rings are simply worn because the previous owner didn't take care of their car.
Any insight is appreciated

Thanks,
oma

Well, omadab, I'm late, but I'll give you my take on your observations. Black soot on the tail pipes of this car is quite common. It runs rich at start up for emission reasons. Quite normal.

So the oil smells like gasoline - well, a little gas does escape the piston oil rings on all engines and it don't take much gas to smell up a storm. Not to worry.

Piston rings being worn, yep they all are on most engines - to a degree. I wouldn't worry about the oil rings being too warn unless you can see blue smoke coming out of the tail pipes after the engine has warmed up.

Now, back in the day, if you are listening to those old coots, a black exhaust pipe usually meant the car was running rich (it needed to have the carburetor adjusted/timing adjusted). If a car was "burning oil" (like blue smoke pouring out the tail pipes) it usually would lay down a blue smoke screen. If "smoke" was coming out from under the car, there was a good chance the piston compression rings were shot, creating blow by through the crankcase.

(hey - who yanked ol humfrz's chain?)


humfrz

[humfrz]

Originally Posted by omadab

So would you say it is because of oil dilution? I don't even want to take the risk on this car anymore. I don't think there's anyway for me to check if its an injector, worn engine or having tons of short trips.
I think its important to mention that the car is also sitting in a show room at the dealership, so I doubt it goes through many short trips.

Well, although short trips aren't the best life for a car, they don't usually damage it. One good "Italian tune up" (long, hot trip) usually clears it out. Mostly true of older cars, not so much newer cars - with them new fangled computer things - ).


humfrz

PS

Well, that's your call.

I would suggest that if the car you're looking at hasn't been power modified (header - forced induction) or tracked extensively (sometimes indicated by suspension modifications), has a howling TOB, it has the transmission you like, the color you like and isn't showing any trouble codes - it's most likely OK.


PSS as you are finding out - it's real easy to over think buying a used car -

[Tcoat]

You can not walk up to a random car and diagnose it's condition from the amount of soot in the tail pipe. If you have a baseline and you watch closely you may be able to notice a change but the simple presence of soot is meaningless. The tips of these cars have a nice big surface area that holds soot. Unless you clean them on a regular basis it will build up more than some cars. It is fine.

[bfrank1972]

Omg. Paranoia. Move on and find another car with clean tips so you will feel better

Sent from my SM-G965U using Tapatalk

[Lantanafrs2]

Internal combustion is on it's way out anyways. Teslas have clean tailpipes.

[omadab]

Thank you everyone for your two cents. I agree with @humfrz, I probably am overthinking the purchase of the car. I'll sit on it for a couple of days then make my choice... unless another beauty comes along haha

[Grady]

If you are worried about soot you only option is...




However they all lie to you about zero emissions! Do you realize how much oil and gas is consumed to manufacture and maintain a car?

[Dr. BRZ]

Short answer. Its normal.

[wally]

I can't comment on the oil smelling like gasoline. But my tips are also black as shit due to cold starts. I got the cats and straight pipes after that. So atleast you don't have to worry about that =)

[steve99]

Run E85 my exhaust has no residue and my oil doesnt go black (my e85 is true 85% ethanol all the time)