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Oil catch can or open breather?

15K views 29 replies 14 participants last post by  ShamrockRally 
#1 ·
On our old engines, I don't see the point of an oil catch can. Why not just put an air filter on the end of the breather tube? Excess oil will eventually just run back into the area under the cam cover, which is fine, right?

Am I missing something?
 
#3 ·
Depends on engine build and use. Below is a 1600 "street" engine, which is actually a pure race engine I drive on the street. It has both a front GTA breather and rear breather. Both are set up like road-draft tubes, just ending below the frame rails. Normally, nothing comes in or is blown out other than at high rpm, where a very fine oil mist blows out. Little condenses on the clear tubes, but what-ever does, drips out. This is a fairly fresh engine, and essentially no measurable oil is lost from the sump between oil changes. Track use with this same engine requires catch cans.
 

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#4 ·
Depends on motor and use.
My "other" car had a very tired motor. I ran the vent hose to a regular oil bottle. Not pretty, but kept the air filters alive.
My wife had a turbocharged mini. I installed a catch can and was amazed at how much oily condensation I would drain out every month or so. Prior to the catch can the misty oil helped contribute to a burned exhaust valve.
On my spider, I just have a 18" length of hose with the small filter on the end.
 
#6 ·
While the subject is open (pardon my intrusion if i’m Hijacking your thread), can you guys tell me what the short tube bent downward coming out of the back of my block is? ‘67 1600 By the way. I would say draft tube but it’s not long enough to reach down into the airstream.

Thanks
Mark
 
#7 · (Edited)
Crankcase blowby outlet/vent.

On my Sprint GT, I installed a hose and attached an oil can full of steel wool to catch the blowby oil. Fair amount, that. Later engines have an oil vapor collector installed as stock. They tend to be only a little efficient.

In the 164, you can get oil running into the rubber intake bellows, downstream from the AFM, from the OVC outlet pipe which is connected to the intake bellows, esp if the little drain/return tube at the bottom of the OVC is plugged with crud, a common occurrence.
 
#8 ·
Hi Del,
Here's a "catch". Sometimes engines inhale through breathers and will suck stuff in. Fine steel wool dust is not too good. Ferrari, on the double breathers on the old V-12's, used copper wool, and we sometimes replace it today with either more copper wool (heavier than steel wool) or stainless steel pot scrubbers! The latter have big curlies of SS, quite heavy, wont corrode as copper wool does, and cannot be inhaled.
 
#9 ·
I misspoke when I said steel wool, as what I had was bronze wool from another project.
My father used it when he rebuilt aircraft engines. I was just thinking generic when I wrote the above. You are correct otherwise. Merry Christmas.
 
#12 · (Edited)
I'm open to air on my Spider.

On the S-4 Spider's there is a gasket where the breather hose attaches to the cam cover which has a small hole in it, way less then half the size as the CCV opening.

I replaced that gasket to utilize the full opening to reduce crank case pressure.

The catch can is on the driver's side of the engine bay. I backe dated the dip stick tube to one with a oil return nipple on it, so whatever goes to the catch can gets returned to the crank case.

There is an oil return nipple on the right side of the block that can be used too. That's the one the later Spiders used with the stock oil vapor separator.
 

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#14 ·
I like the oil pressure gauge in the corner, I assume thats a mechanical one to check what the real pressure is? I'm planning on doing the same, but to run the gauge inside the car to keep an eye on it whilst on the road.
 
#22 ·
Lovely Machinery!

Sometimes I suspect there are a few members lurking on the BB who are just looking for opportunities to show off their awesome engines! :wink2:

As well, I hasten to add, to contribute knowledge and wisdom to the discussion. :smile2:

To take this discussion a little off topic, I wonder how many members are aware of issues with Gasoline Direct Injection (GDI) which, because the port injector is no longer present to continually wash down the the intake tract and and back of the intake valve with that fine, high-detergent, Tier 1 fuel we all use, can result in really messy situation. And no, fuel additives are not any help, since the gas in GDI never enters the intake plumbing.

Ford Ecoboost engines were among the most troubled, with misfires and poor fuel economy presenting in as few as 10k.

Of course, we need not be concerned about hot, turbo-boosted air or Exhaust Gas Recirculation (EGR) in our 2.0L, but I'd still be concerned about putting valve cover blow by, along with acidic products of combustion back into the intake manifold and crankcase.

Hey, wait a minute!

That's exactly what our oil vapor collector (OVC) does, until it gets so clogged it begins to pop the dipstick. That's how I discovered mine was blocked. Now of course, it returns fumes to the intake and recovered oil back to the crankcase.

Guess it's no big deal.

Back to GDI, I did some research on the new Nissan engines, and they include a port injector on each cylinder to provide cleaning, while the DI works to improve performance and economy (as well as, unfortunately, particulates.:frown2:).

Also drove a GDI Hyundai Limited recently and while the salesman was stumped about how they mitigate intake fouling (no port injector) a knowledgeable service rep said they recommend a $180, chemical intake cleaning every 15,000 miles. How many owners are going to let that problem fester till it becomes more than a nuisance, only to discover their baked on crud won't respond to chemicals and needs mechanical cleaning (walnut shells?) often requiring pulling the heads (!) like I've heard some BMWs need. (Hmmm, think I may need a question mark here :smile2:)

Oh well, no free lunch...

Now I'm gonna go back and look at those beautiful engines!

Happy New Year all!
 
#23 ·
Though maybe not as bad as DFI but our little twin cam is pretty notorious for carboning up too.


Sometimes I suspect there are a few members lurking on the BB who are just looking for opportunities to show off their awesome engines! :wink2:

As well, I hasten to add, to contribute knowledge and wisdom to the discussion. :smile2:

To take this discussion a little off topic, I wonder how many members are aware of issues with Gasoline Direct Injection (GDI) which, because the port injector is no longer present to continually wash down the the intake tract and and back of the intake valve with that fine, high-detergent, Tier 1 fuel we all use, can result in really messy situation. And no, fuel additives are not any help, since the gas in GDI never enters the intake plumbing.

Ford Ecoboost engines were among the most troubled, with misfires and poor fuel economy presenting in as few as 10k.

Of course, we need not be concerned about hot, turbo-boosted air or Exhaust Gas Recirculation (EGR) in our 2.0L, but I'd still be concerned about putting valve cover blow by, along with acidic products of combustion back into the intake manifold and crankcase.

Hey, wait a minute!

That's exactly what our oil vapor collector (OVC) does, until it gets so clogged it begins to pop the dipstick. That's how I discovered mine was blocked. Now of course, it returns fumes to the intake and recovered oil back to the crankcase.

Guess it's no big deal.

Back to GDI, I did some research on the new Nissan engines, and they include a port injector on each cylinder to provide cleaning, while the DI works to improve performance and economy (as well as, unfortunately, particulates.:frown2:).

Also drove a GDI Hyundai Limited recently and while the salesman was stumped about how they mitigate intake fouling (no port injector) a knowledgeable service rep said they recommend a $180, chemical intake cleaning every 15,000 miles. How many owners are going to let that problem fester till it becomes more than a nuisance, only to discover their baked on crud won't respond to chemicals and needs mechanical cleaning (walnut shells?) often requiring pulling the heads (!) like I've heard some BMWs need. (Hmmm, think I may need a question mark here :smile2:)

Oh well, no free lunch...

Now I'm gonna go back and look at those beautiful engines!

Happy New Year all!
 
#30 ·
My update to this thread- I put together a proper airbox from ebay parts, Centerline, and Classic Alfa. I couldn't find the rear exit/left hand vent connection for the breather, but was able to use a heater hose to make things work. Small hose at the cam breather connects under the air box. All sealed up and nothing (extra) going down on the road.
1652686
 
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