Hey! what is that smoke coming out the back of my SVX anyway?????
 

Hey! what is that smoke coming out the back of my SVX anyway?????

I am looking for opinions on what makes smoke come out the tail pipes. So go on and jump in here if you got any idea at all.

I’ll run through a few of the facts:
Engine 250k miles and climbing
Leaking rear engine crank seal
Transmission with about 260k miles since it was rebuilt before I bought the SVX
Trans is leaking out the front some but not real heavy.
The engine uses a quart of oil oh about every 1000 miles
The trans uses about 1 qt every 15,000 miles or so. 2 qt per year
The PVC system looks clean with no oil in the hoses

So here’s the smoke part. I have been trying to get better gas mileage because I drive a lot. Hey I have been doing better in this area I have been getting around 28 mpg which is a lot better than the 24 I used to get.

It has been my thinking that by being light on the accelerator and never nailing it I would get great gas mileage. Well then when I do nail it maybe after about 2 months of light throttle driving there is a cloud behind the SVX. So then if I do it again there is less of a cloud and the third time no cloud at all……… Then if I drive for a day which is around 120 miles and nail it again there is no cloud.

Now one time a guy I know was behind me. I was showing off and nailed it. The cloud appeared behind me. He said the engine was running rich when he saw the black cloud and said it was running rich because it was black and not blue. Yeah I just nailed it and pulled away from him and left him in the gas cloud. :D

So what do you think this is?

How can it run rich and then not run rich after repeated throttle stomps?
Can it be carbon or something else from the catalytic converter that gets blown out?
Can it be carbon from build up on the intake valves that gets blown out?

Thanks and take care of that SVX

John

Um... you have 250k on it. It's probably burning oil, right?

Yeah. Mine does the same thing. It's a subaru, it's oil.

When I picked up the 94, it had been sitting for almost a year. The owner said they only started it once in a while and revved it up a bit.

On the way home I gassed it a couple of times and man ... the smoke blewwww out. Black as .... you know what!

It hasn't done it since. I do not drive it hard but regularly go through the gears on full throttle. The car doesn't burn any oil.
Yours probably needs to be driven a bit more often on full throttle.

They used to say that about the 60's high performance cars that were driven by little old ladies. They always blew black smoke when you gassed them for the first few times. ;)

Using a quart every 1000 miles is too much.

Don't know ... but it was pretty typical on my subes with over 200,000 on them.
Didn't burn oil up in smoke clouds but it disappeared just the same.
Typical stuff , like leaks in several places on the engine will do that.

Had a dodge 273ci engine that used a quart every 500 miles. Rear main seal. Didn't leak on the driveway, just coated the clutch. Replaced the clutch 3 times in a year. Just couldn't stop it. It didn't burn a drop of oil.

I'd say at 250K you're probably approaching the end of the lifespan of some of the engine internals, piston rings, bearings, and definitely seals. IMO your engine is burning oil because the piston rings are worn and no longer sealing as well, allowing oil blowby into the cylinder. Time for new rings.

When your SVX smokes ...

Usually it's not burning oil if the smoke is black. Could be fuel/air mixture or a carbon build up.
Burning oil is almost always blue smoke. Rings or valves. ( or Hondas ;) )
Blown head gasket is usually white smoke. Water infiltration.

sorry ... couldn't resist the Honda comment. :)

yup
 

redsvx nailed it.

black smoke: fuel
blue smoke: oil
white smoke: coolant

you could have fouled plugs or something along the line of running rich.

Okay
Thanks for the comments. 
So the engine is old and worn out?
This is what I am trying figure out is the engine worn out?
As I may decide to replace the engine and trans at the same time.

The oil usage also includes the leaking rear crank seal.
So at 1qt per 1000 miles some is being burned and some is leaking.
I do not know how much is leaking out.
There are no other oil leaks.
I fixed the valve covers last year.
The front of the engine is dry.
The sides of the engine are dry.
The back of the engine has got oil.

I think the engine plugs and other fuel-ignition systems are working fine.
It is getting 28 mpg.
I think that if there was a problem in this area the mpg would be less

So what I don’t understand is this.
If the engine is burning oil……..
Where does all the burn oil sit in between throttle stomps?
Is it sitting in the CATs?
Why is there no more smoke after a few throttle stomps?

So let’s just say that it is the rings and the rings are worn out or have wear.
I have seen many cars smoke like crazy when the throttle is released and the engine does the braking.
Would there not be more smoke when throttle is released at high rev’s in low gears?
Doesn’t this pull the oil past the rings into combustion chamber with this extended high vacuum?

From what I know the rings can leak two ways.
During combustion, power stroke, there is blow-by of air/gas and then burned combustion products into the crank case.
During the intake stroke with vacuum in the cylinder oil can be pulled into the cylinder and burned.

I have had other cars with high mileage and worn engines.
The PVC system tells this worn ring story.
The inside of the PVC hoses are usually covered with oil.
The PVC system has no vacuum at WOT to pull blow-by into the intake.
So it doesn’t pull worn ring blow-by air/gas out of the crankcase at WOT.
The crankcase WOT blow-by is expelled backward thru the PVC fresh air hoses.
This blow-by oil would show up in the throttle body air intake hose before the throttle body.
It shows as a black gunky thick oil coating before the throttle plates.
And means the engine rings are worn.

What about leaking intake and exhaust valve seals and guides?
The leaking oil would get burned and stick to the valves as carbon.
This would be carbon build-up on the valves
Smacking the throttle would blow all of this carbon out.
Smack the throttle again and there less carbon to blow off the valves.

Probably because it is not burning oil. :)
Engines that burn oil do it constantly. Like a blue trail of smoke all the time ... sometimes even at idle, but not as noticeable.
Has a distinct smell too. :( Have someone else drive your car and you follow. Watch and smell.
Or ... try an additive for fixing burning oil like STP or something.
That stuff stops burning oil quickly although temporarily.
But I still think yours is fuel.

You could always try that RESTORE stuff. I used it in my SVX once, and I got the best MPG I ever had on a roadtrip. 27.9mpg. IMHO, that's proof that the stuff works.

It's pretty good stuff for working 'with' the oil to stop any oil consumption that is not seal related.
Not really considered one of the 'additives' since it works independently of the oil.
Here's a link to an independent test of the product.

http://www.atvconnection.com/Feature...e-Restorer.cfm

Can't hurt to try it. :)

Before dumping any mystery gunk into your engine, you should probably take a shot at using seafoam to clean the injectors, ect. If there's anything that'll burn gunking up the engine, it'll get smoked out all in one shot

A quick question: Does the car smoke during start-up?This could shed some light on the situation, especially if you discover its infact oil burning and not fuel

This that stuff I used once in the Colt Vista I had. It is thick like honey. Now I usually warm stuff like this up before I add it in. I think the Colt vista spun a bearing after I used this :rolleyes: Longassname is saying not to use anything above a 10w-30 oil. Says the connecting rod clearance can effect the oil flow. So I don't know IF I would use this. I have used Lucas engine oil additive which is also thick for about 2 years. I don't use that any more either. Oil consumption can be high when the rings get all gunked up. Gunked up rings are more common with thicker oil usage. The thick oil increases the pressure at the oil pump and can make the front crank seal leak. So I don't use it any more, just plain old 10w-30 for now.

If I am buring oil and the lead from the restore gets into the CAT it will kill it.
Lead has low melting point. It will not stay in the cylinders.

I have used Lubrilon engine treatments. They've got ALL the test to back up the products. http://www.xcelplus.com/



Thanks

John