Ok to pull the ozone generated in an ignition distributor trough the PCV system?

[ELS122]

In a car's engine distributor there's a bit of ozone generated in the distributor, there's vent holes in the distributor cap for vent this and keep it from corroding the contacts in the distributor.
But would opening up a vent from the distributor to the crankcase so it is not just vented but circulates air ok for the oil? Would the oil react with the ozone and cause problems?
   With a PCV system the crankcase is under a slight vacuum and air is circulated trough it so oil sludge doesnt form as quickly from the moisture.
The gases in the crankcase are mainly water vapor, nitrogen and CO2. And since it's a PCV system it also pulls trough fresh air so add oxygen to that mix
So would ozone be very reactive with any of those things?

[John B]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

[ELS122]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

That's a common misinterpretation of the term, I think whoever coined the term meant that it positively circulates, not that there's positive pressure.
And it is under a vacuum around 20-50mbar under atmospheric iirc. But in my case I'm running a much higher vacuum of around 500mbar to promote better ring seal.
The intake vacuum is around 700mbar so 0.3bar absolute, this goes to nearly 0 when you open the throttle fully.
There is an actual check valve in every PCV system that blocks a backfire traveling to the crankcase and igniting the unburnt gasoline vapors which could be present there.

Anyway, the point is I can easily get flow trough the dizzy to circulate air. I could plumb a different vacuum line separate from the PCV system but that will just turn into a vacuum line mess, so I'm wondering if it's ok to just have the tiny bit of ozone constantly flowing trough the crankcase, getting in contact with the oil.

[Gyro]

Aren't you just going to suck a load of (possibly damp) outside crud into the distributor cap? What's the actual problem you're trying to solve?

[John B]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

That's a common misinterpretation of the term, I think whoever coined the term meant that it positively circulates, not that there's positive pressure.
And it is under a vacuum around 20-50mbar under atmospheric iirc. But in my case I'm running a much higher vacuum of around 500mbar to promote better ring seal.
The intake vacuum is around 700mbar so 0.3bar absolute, this goes to nearly 0 when you open the throttle fully.
There is an actual check valve in every PCV system that blocks a backfire traveling to the crankcase and igniting the unburnt gasoline vapors which could be present there.

Anyway, the point is I can easily get flow trough the dizzy to circulate air. I could plumb a different vacuum line separate from the PCV system but that will just turn into a vacuum line mess, so I'm wondering if it's ok to just have the tiny bit of ozone constantly flowing trough the crankcase, getting in contact with the oil.

This still isn't making any sense. If the crankcase is under vacuum with respect to the intake pressure, where is air going to in the crankcase? It's not enough pressure to bypass the ring seals.

The reverse however is true, even in a healthy engine, a small amount of combustion gases under extreme pressure bypass the ring seals, in addition to the production of oil and water vapour resulting in positive crankcase pressure.

Regardless of whether an engine is port injection, direct injection turbo NA etc, the results of PCV crud and build up are evident, and more so evident of which direction the gases and oil vapours are flowing.

Check out the intake ports of direct injection engines that have a few years of use on them, now imagine that crap in your distributor!

[Benta]

This still isn't making any sense.

Amen! But the OP has some parallel-universe ideas about IC engines. Just let it roll.

[Circlotron]

Interesting subject. Some race engines use a vacuum pump to keep the crankcase in negative pressure. Helps keep the rings from moving away from the lower ring lands as the piston decelerates at top dead centre. As for the original question, I’d say put a check valve in the line from the dizzy cap to the crankcase so no fumes can ever flow back into the cap unexpectedly. And given the amount of ozone produced would be small compared to the total airflow in the crankcase I’d say it’s not going to cause a problem. But yes, ozone is reactive. Would the antioxidants in the oil also work with ozone? Actually, does ozone support combustion? If it speeds it up while maintaining the same AFR that might be beneficial.

[langwadt]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

That's a common misinterpretation of the term, I think whoever coined the term meant that it positively circulates, not that there's positive pressure.
And it is under a vacuum around 20-50mbar under atmospheric iirc. But in my case I'm running a much higher vacuum of around 500mbar to promote better ring seal.
The intake vacuum is around 700mbar so 0.3bar absolute, this goes to nearly 0 when you open the throttle fully.
There is an actual check valve in every PCV system that blocks a backfire traveling to the crankcase and igniting the unburnt gasoline vapors which could be present there.

Anyway, the point is I can easily get flow trough the dizzy to circulate air. I could plumb a different vacuum line separate from the PCV system but that will just turn into a vacuum line mess, so I'm wondering if it's ok to just have the tiny bit of ozone constantly flowing trough the crankcase, getting in contact with the oil.

This still isn't making any sense. If the crankcase is under vacuum with respect to the intake pressure, where is air going to in the crankcase? It's not enough pressure to bypass the ring seals.

The reverse however is true, even in a healthy engine, a small amount of combustion gases under extreme pressure bypass the ring seals, in addition to the production of oil and water vapour resulting in positive crankcase pressure.

Regardless of whether an engine is port injection, direct injection turbo NA etc, the results of PCV crud and build up are evident, and more so evident of which direction the gases and oil vapours are flowing.

Check out the intake ports of direct injection engines that have a few years of use on them, now imagine that crap in your distributor!

oil fumes might help the crud stick but most of the crud is from EGR

[Circlotron]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

The line to the intake without a check valve is located on the atmosphere side of the throttle and normally serves as an air inlet to the crankcase. There is a second line that has the PCV valve that regulates the airflow out of the crankcase and is connected to a low pressure point downstream of the throttle. Normally air flows in the first line and out the second, but with a very worn and fumey engine the blowby gases will often exit where the air should be going in because of the excessive flow of these gases. Luckily they still get sucked down the intake and burned,  not vented to atmosphere as was the case with Stone Age engines.

[ELS122]

Are you sure the crankcase is under vacuum? It is a positive crankcase valve afterall.

Typically in an NA vehicle its plumbed straight to the intake without check valves, with the intake being of slightly lower pressure and the crankcase being higher due to heat, and turbulence. You don't want it plumbed to anywhere else.

That's a common misinterpretation of the term, I think whoever coined the term meant that it positively circulates, not that there's positive pressure.
And it is under a vacuum around 20-50mbar under atmospheric iirc. But in my case I'm running a much higher vacuum of around 500mbar to promote better ring seal.
The intake vacuum is around 700mbar so 0.3bar absolute, this goes to nearly 0 when you open the throttle fully.
There is an actual check valve in every PCV system that blocks a backfire traveling to the crankcase and igniting the unburnt gasoline vapors which could be present there.

Anyway, the point is I can easily get flow trough the dizzy to circulate air. I could plumb a different vacuum line separate from the PCV system but that will just turn into a vacuum line mess, so I'm wondering if it's ok to just have the tiny bit of ozone constantly flowing trough the crankcase, getting in contact with the oil.

This still isn't making any sense. If the crankcase is under vacuum with respect to the intake pressure, where is air going to in the crankcase? It's not enough pressure to bypass the ring seals.

The reverse however is true, even in a healthy engine, a small amount of combustion gases under extreme pressure bypass the ring seals, in addition to the production of oil and water vapour resulting in positive crankcase pressure.

Regardless of whether an engine is port injection, direct injection turbo NA etc, the results of PCV crud and build up are evident, and more so evident of which direction the gases and oil vapours are flowing.

Check out the intake ports of direct injection engines that have a few years of use on them, now imagine that crap in your distributor!

"And it is under a vacuum around 20-50mbar under atmospheric"
A PCV system works by having both a crankcase vent connected to intake vacuum, and a vent to atmospheric pressure to suck in air.
The oily buildup in the intake from the PCV is not from the outside air, it's from the crankcase.
There is no way that crud can get in the distributor if the PCV system is working correctly.

Why are you bringing ring seal to this? I specifically am talking about weather or not the ozone drawn from the distributor has any negative impact on the oil.

[BrokenYugo]

No.

[ELS122]

No.

Didn't have to get into so much detail as to why...

[AVGresponding]

No.

Didn't have to get into so much detail as to why...

Largely because the quantities involved will be insignificantly small.

Interesting subject. Some race engines use a vacuum pump to keep the crankcase in negative pressure. Helps keep the rings from moving away from the lower ring lands as the piston decelerates at top dead centre. As for the original question, I’d say put a check valve in the line from the dizzy cap to the crankcase so no fumes can ever flow back into the cap unexpectedly. And given the amount of ozone produced would be small compared to the total airflow in the crankcase I’d say it’s not going to cause a problem. But yes, ozone is reactive. Would the antioxidants in the oil also work with ozone? Actually, does ozone support combustion? If it speeds it up while maintaining the same AFR that might be beneficial.

This is more of a beneficial side effect; the primary reason is to reduce aerodynamic drag on the crank.

[John B]

I think I see the argument here now. He's suggesting the air movement is from:

presumably post airflow meter > crankcase > intake manifold

I suggest plumbing the PCV with clear PVC for a while to see where it turns a nice shade of brown from the oil vapour. I'm also unsure of how you hope to plumb a distributor in an airtight way, but I would expect unmetered air to be entering the manifold. And lastly I would suggest there's a reason why literally noone does this.

[Circlotron]

Back in 1978 the brother in law had a Suzuki LJ80 4WD and it had a distributor cap with an air inlet and outlet although I think this might have been more to do with keeping the inside of the cap dry after splashing around in wet conditions.

The issue of unmetered air entering the inlet manifold is something I hadn't thought of. The inlet to the distributor would need to be downstream of the airflow sensor as John B alludes to. And maybe a bead of silicone around the bottom edge of the cap.

[ELS122]

I think I see the argument here now. He's suggesting the air movement is from:

presumably post airflow meter > crankcase > intake manifold

I suggest plumbing the PCV with clear PVC for a while to see where it turns a nice shade of brown from the oil vapour. I'm also unsure of how you hope to plumb a distributor in an airtight way, but I would expect unmetered air to be entering the manifold. And lastly I would suggest there's a reason why literally noone does this.

You're assuming I'm talking about an engine with a points distributor and a MAF sensor for EFI? how many of those exist?

[John B]

It's really not the biggest issue in this situation.

[langwadt]

I think I see the argument here now. He's suggesting the air movement is from:

presumably post airflow meter > crankcase > intake manifold

I suggest plumbing the PCV with clear PVC for a while to see where it turns a nice shade of brown from the oil vapour. I'm also unsure of how you hope to plumb a distributor in an airtight way, but I would expect unmetered air to be entering the manifold. And lastly I would suggest there's a reason why literally noone does this.

You're assuming I'm talking about an engine with a points distributor and a MAF sensor for EFI? how many of those exist?

probably quite a few of them 30 years ago

[John B]

Towards the late 80's and early 90's there was a crossover period where the electronics weren't keeping pace with emission demands. For some reason injector and ignition outputs were costly (I dont know what the problem was, maybe lack of computing power), it so you saw all kinds of combinations including a single injector output (single point injection, essentially glorified electronic carburetors) and distributors.

[langwadt]

Towards the late 80's and early 90's there was a crossover period where the electronics weren't keeping pace with emission demands. For some reason injector and ignition outputs were costly (I dont know what the problem was, maybe lack of computing power), it so you saw all kinds of combinations including a single injector output (single point injection, essentially glorified electronic carburetors) and distributors.

single point injection is a simple bolt on, once you start doing multi point and sequential injection you need more timing signals

[John B]

Sure, but even when the engine had crank and cam angle signals, it was common for 6 and 8 cyl engines to employ wasted spark and semi sequential injection to halve the number of inj and ign outputs. I never quite got an explanation for that, so I always put it down to a lack computing power that we now take for granted.

[langwadt]

Sure, but even when the engine had crank and cam angle signals, it was common for 6 and 8 cyl engines to employ wasted spark and semi sequential injection to halve the number of inj and ign outputs. I never quite got an explanation for that, so I always put it down to a lack computing power that we now take for granted.

with wasted spark you can half the number of coils and with wasted spark and/or semi sequential injection you can ignore the cam timing

[TERRA Operative]

The crankcase is under pressure from blow-by gasses passing the piston rings, these gasses are fed back into the intake to be burnt for emissions reasons.

Plumbing your distributor cap to the crank will just fill it with an oily film.

IMHO, a distributor would make for a pretty poor oil catch can.....


You'd do much better to just upgrade to full electronic ignition. Or just leave it well enough alone besides scheduled servicing.

What actual engine are we talking about, out of interest?

[bdunham7]

You're assuming I'm talking about an engine with a points distributor and a MAF sensor for EFI? how many of those exist?

Why would anyone assume points?  Did you mention that?

As far as plumbing a line into the distributor, send it to the intake manifold with a restrictor orifice to limit flow.  Some people claim that helps with combustion, but I don't know about that.  Plumbing into your PCV system is going to end up with oil vapors getting in there one way or another--perhaps reversion or maybe fumes evaporating after you turn the engine off.  PCV systems always end up oily everywhere inside no matter how many check valves and elbows there are.