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Catch can


Rusty Dawg

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Howdy,

 

I am planning to install a catch can in my J13 engine because the blow by seems to have become fairly intense and I need to keep that oil out of my intake.  I removed the hose that went from my valve cover to my air filter housing to stop the oil from entering the intake and placed a mesh over the valve cover outlet, but it still spews oil out of it.  I would like to trap the oil since it is leaking oil down the backside of my engine.  Has anyone installed one before in such an engine?  Can anyone recommend a name brand or type that I should be looking at for installation?  I have an idea of what I would like to go with, but thought I would throw it out there to see if anyone has specifically installed it my type of engine.

 

Thanks!

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You going to recycle the oil from the catch can or just throw in the garbage. If the latter you may as well just run a longer hose down beside the starter and let it drip on the road just like cars used to do before the '60s.

 

See the dark lines in the middle of the lanes? That's from older engines that had a 'draft tube'. It was a pipe from the valve cover down under the engine where a low pressure formed while driving that pulled the fumes out.

 

Highway 1950s Photos and Premium High Res Pictures - Getty Images

 

This will not stop all the oil from getting into the intake. You still have a PCV valve.

 

I would leave connected and burn the fumes and oil.

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1 hour ago, Charlie69 said:

Why is there so much crank case pressure?

I am guessing that having a just as new head has created more pressure and with what I am guessing to be worn rings, I have more pressure built up.  I thought initially that I had overfilled that crankcase even though I went with the factory specs with oil filter change, but even with the removal of some oil that put me at the "full" level on the dipstick, there was still oil in my air filter housing and a 1/4 of my air filter was soiled with oil.

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1 hour ago, datzenmike said:

You going to recycle the oil from the catch can or just throw in the garbage. If the latter you may as well just run a longer hose down beside the starter and let it drip on the road just like cars used to do before the '60s.

 

See the dark lines in the middle of the lanes? That's from older engines that had a 'draft tube'. It was a pipe from the valve cover down under the engine where a low pressure formed while driving that pulled the fumes out.

 

This will not stop all the oil from getting into the intake. You still have a PCV valve.

 

I would leave connected and burn the fumes and oil.

Oh man, I had no idea....cool illustration.  I really don't care to recycle the oil.  What do you mean that it "will not stop all the oil from getting into the intake"?  If the hose is going down towards the road and not into the air filter housing, I shouldn't get any oil in the intake, no?  Would I still have an inline PVC on this hose?

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The PCV (positive crankcase ventilation) is a one way valve that uses small amounts of intake vacuum to draw fumes out of the engine and burn them. If you are blowing oil droplets out the valve cover hose you will be sucking them into the intake as well.

 

In normal use the air drawn out is replaced by filtered air from the air filter, piped to the valve cover. On worn engines, the blow-by past the rings over powers the PCV system and it reverses out the valve cover hose and normally into the carburetor. 

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28 minutes ago, datzenmike said:

The PCV (positive crankcase ventilation) is a one way valve that uses small amounts of intake vacuum to draw fumes out of the engine and burn them. If you are blowing oil droplets out the valve cover hose you will be sucking them into the intake as well.

 

In normal use the air drawn out is replaced by filtered air from the air filter, piped to the valve cover. On worn engines, the blow-by past the rings over powers the PCV system and it reverses out the valve cover hose and normally into the carburetor. 

Not sure I follow.  If the hose is going from the valve cover directly towards the ground, how is it sucking the oil droplets into the intake as well?  Or are you saying that in normal set ups there would be a tee that ties in a PCV valve to the air cleaner intake?  The blow by is strong enough to where I had oil in my air cleaner housing/carburetor.

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 The PCV valve is connected to the block vent and the small vacuum from the intake draws oil and water vapors out of the crankcase. The PCV valve has a small enough opening that it doesn't affect the intake vacuum and has a one way valve and spring inside to prevent the possibility of a backfire traveling back into the engine. The air drawn out is replaced by air pulled into the valve cover hose from the air filter.

 

 TM-10-3930-653-14P_58_1.jpg

 

If not fouling the plugs too badly, it's a closed system, I would leave it connected up.

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11 hours ago, banzai510(hainz) said:

most blow by is at idle.

once engine speed goes up the air gets sucked into the crank case.

 

if you open the cranck case vent and it smells bad at idle its more or less massive blowby.

 

but dont do like soem Morons and they plug the crank case vent thinking they fixing the proplem

I filled the vent with the material from a scourer, but it still leaked a lot.

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11 hours ago, datzenmike said:

 The PCV valve is connected to the block vent and the small vacuum from the intake draws oil and water vapors out of the crankcase. The PCV valve has a small enough opening that it doesn't affect the intake vacuum and has a one way valve and spring inside to prevent the possibility of a backfire traveling back into the engine. The air drawn out is replaced by air pulled into the valve cover hose from the air filter.

 

 TM-10-3930-653-14P_58_1.jpg

 

If not fouling the plugs too badly, it's a closed system, I would leave it connected up.

All I see is the vent on the valve cover that had a hose connected to the air cleaner housing.

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All N American cars have a PCV valve since '62. Surely the J13 will also have this set up. Let me look into this.

 

Just what's wrong with having the hose connected to the air filter housing?

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I have made a few catch cans like the one pictured below. It has a baffle in it that separates the valve cover inlet from the block return line. I use a filter on the top, but it can also be hooked up to a PCV valve for a proper negative crankcase pressure system.

 

For what it's worth, race cars use a similar setup because in high performance engines, blow-by is just normal.

 

IMG_3086Small.jpg?width=960&height=720&f
IMG_3087Small.jpg?width=960&height=720&f

Edited by Stoffregen Motorsports
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14 hours ago, datzenmike said:

All N American cars have a PCV valve since '62. Surely the J13 will also have this set up. Let me look into this.

 

Just what's wrong with having the hose connected to the air filter housing?

 

The roadster and RL411 type R engine [1600 cc] had a clever setup.  The engine is tilted from front to back, no surprise there.  The finned cast aluminum valve cover serves as a condenser for oil fumes etc.  The condensate flows to the rear, meets a sheet metal diverter and returns the condensate to the engine sump.  Any remaining fumes go to the inlet side of the air filter where any particles are trapped by the air filter, not sent in to the SU carbs to foul them up.  No PCV valve per se, the valve cover and sheet metal diverter do the job.  Meets all air polution standards.

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2 hours ago, MikeRL411 said:

 

The roadster and RL411 type R engine [1600 cc] had a clever setup.  The engine is tilted from front to back, no surprise there.  The finned cast aluminum valve cover serves as a condenser for oil fumes etc.  The condensate flows to the rear, meets a sheet metal diverter and returns the condensate to the engine sump.  Any remaining fumes go to the inlet side of the air filter where any particles are trapped by the air filter, not sent in to the SU carbs to foul them up.  No PCV valve per se, the valve cover and sheet metal diverter do the job.  Meets all air polution standards.

Even just that small amount of vacuum from the open end of the carbs is enough to help with oil leaks.

 

So the baffle is like an L series, but open on both ends instead of just the one end?

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No PCV valve, the hose from the valve cover is it. Carburetor sucks fumes and any aerosol oil.

 

 

You want to look for a catch can that will filter out the oil droplets effectively and trap them. The remaining 'cleaned' air is just fumes that can be piped to the air filter stock location and burned. Some cheap and not so cheap catch cans just dump the fumes through a tiny filter under the hood. These are going to get into the cab where you can huff them and get brain cancer.

 

 

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I tried to find pics of an oil/air separator I installed a few years ago, but I couldn't find them.

 

These are excellent at dealing with the mix of air and oil, but they need periodical draining, which is a pain. They aren't clear, so you need to unscrew them to inspect. You never know how much oil you will find.

 

https://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=oil air separator

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I do not remember if the L16/18s have the screen in the block for the crank case vent (PCV tube).  If that is missing or damaged this will cause blow by. My L20B has it.

 

https://datnissparts.com/pcv-crankcase-net-screen-datsun-nissan-l4-naps-z-l16-l18-l20b-z20-z22-z24-11037-21001/

 

 

Edited by Charlie69
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This is a J13. No block vent just a pipe on the top of the valve cover to the inside of the air filter. The oil droplets have a long path to travel to get up there and lots of time and surfaces to attach to. The top of the valve cover will also have some baffles to keep cast off from the rocker arms out. This is for a good running engine. One with lots of blow-by will push the mist of droplets along much faster and could very well spit them into the carburetor.

 

 

 

 

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On 6/23/2021 at 7:00 PM, datzenmike said:

All N American cars have a PCV valve since '62. Surely the J13 will also have this set up. Let me look into this.

 

Just what's wrong with having the hose connected to the air filter housing?

Soils the air filter and the housing.  For now I just ran a hose from the valve cover to a container I mounted on the fender wall.

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15 hours ago, Charlie69 said:

I do not remember if the L16/18s have the screen in the block for the crank case vent (PCV tube).  If that is missing or damaged this will cause blow by. My L20B has it.

 

https://datnissparts.com/pcv-crankcase-net-screen-datsun-nissan-l4-naps-z-l16-l18-l20b-z20-z22-z24-11037-21001/

 

 

Other than a thread plug on the side of the block, I can't find anywhere else where a PCV would go.  I even looked online to find photos of J13's and couldn't find anything.

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