Smoke update, need advise
Thread Starter
3rd Gear
Joined: Jun 2001
Posts: 3
Likes: 0
From: Portland Oregon
Smoke update, need advise
I posted about a white smoke problem a week ago. I've got more info. I have ran the thing a little and scratched my head trying to figure it out over the last week. It just doesn't smoke most of the time. Last night I ran it hard for a little while and got the smoke again, but then it quit. So I kept going, started smoking hard again so I shut down and called my wife to tow me home, I wanted to get a spark plug read. All the new plugs looked the same, a little sooty, but not bad. Popped the hood and the breather tube from the "oel" fill to the air cleaner had been split open and there was quit a bit of oil in the valley and running down the cam covers. Popped the air cleaner and it was filled too. So it appears to me that I've got an intermittent crank case pressurization problem that blows oil out the vent tube into the intake. Or possibly out the smaller hose that junctions into the vent tube from below, where does that go to?
So, I'm hoping it could be some sort of PCV problem since it is intermittent, and not a collapsed piston or broken rings or something. Any help appreciated.
So, I'm hoping it could be some sort of PCV problem since it is intermittent, and not a collapsed piston or broken rings or something. Any help appreciated.
Burning Brakes
Joined: May 2001
Posts: 1,124
Likes: 11
Matt,
There are usually two sources of smoke,external and internalto your engine.
1. External via oil onto a hot surface with white smoke and a strong smell of hot burning oil as it evaporates.
2. Internal via blow by or leaking valve guides.
Blow by is caused when combustion gases blowing past the piston rings, pressurising the crankcase passing via the Pressure Control Valve into the inlet air passage into the cylinders where it is burnt or by leaking oil via worn valve guides where oil is drawn into the combustion space where it is burnt.
In your case it appears to be happening when driven hard, so it would indicate blow by under full load when the oil become an excessive amound to be completely burnt in the combustion process, hence the smoke. As you have found oil in you inlet air passages from the vent from you oil fill pipe and the PCV piping.
Don't know what type of oil you are using or the temperature conditions you are operating the car under, however you may need to change the oil to a more viscous oil that will hang up in the cylinder and ring area to give a better combustion seal. I would contact you oil manufacture or refer to you owner operating manual to ensure that you are using the right type of oil for your operaating conditions.
I would not recommend jumping to the worst case scenario, just eliminate the various likely scenarios until you locate and solve your problem. There are oils that give you a better top end lubrication and hence a better combustion seal.
Tails 90 S4
There are usually two sources of smoke,external and internalto your engine.
1. External via oil onto a hot surface with white smoke and a strong smell of hot burning oil as it evaporates.
2. Internal via blow by or leaking valve guides.
Blow by is caused when combustion gases blowing past the piston rings, pressurising the crankcase passing via the Pressure Control Valve into the inlet air passage into the cylinders where it is burnt or by leaking oil via worn valve guides where oil is drawn into the combustion space where it is burnt.
In your case it appears to be happening when driven hard, so it would indicate blow by under full load when the oil become an excessive amound to be completely burnt in the combustion process, hence the smoke. As you have found oil in you inlet air passages from the vent from you oil fill pipe and the PCV piping.
Don't know what type of oil you are using or the temperature conditions you are operating the car under, however you may need to change the oil to a more viscous oil that will hang up in the cylinder and ring area to give a better combustion seal. I would contact you oil manufacture or refer to you owner operating manual to ensure that you are using the right type of oil for your operaating conditions.
I would not recommend jumping to the worst case scenario, just eliminate the various likely scenarios until you locate and solve your problem. There are oils that give you a better top end lubrication and hence a better combustion seal.
Tails 90 S4
Burning Brakes
Joined: May 2001
Posts: 1,207
Likes: 2
Matt,
If you were to pull off the oil filler casting, you'd have a big oval hole right
directly above a pair of connecting rods.
What happens is at higher rpm the oil gets
slung up into the housing and the crankcase
venting draws it into the intake system.
Later cars have a baffle here.
Devek sells a baffle just for this problem.
I'd be willing to bet that this is all that
you need.
Jim V
If you were to pull off the oil filler casting, you'd have a big oval hole right
directly above a pair of connecting rods.
What happens is at higher rpm the oil gets
slung up into the housing and the crankcase
venting draws it into the intake system.
Later cars have a baffle here.
Devek sells a baffle just for this problem.
I'd be willing to bet that this is all that
you need.
Jim V