Crankcase breather to catchcan?

[grimlynsan]

Hi all,

 

After my recent trip to Lakeside, it highlighted the need to do something with the oil shot out the side of the block as I went down the straight.

 

 

 

You can see in the pics, there is oil splattered out the filter at the top, and also out the breather on the side.

 

I want to do something better than an olive oil can to eliminate the mess and have searched the internet high and low for inspiration.

 

I even got out my trusty Haynes manual and ever since doing so, I am confused!

 

I thought that as originally plumbed, there was a hose coming out of the tappet cover, and into the intake manifold. This would create a vacuum and SUCK oily vapour from the top of the engine into the intake where it would be burned.

 

But in the diagram in the Haynes is has arrows indicating the opposite, and that air is being sucked INTO the top of the engine.

 

If they Haynes manual is right and I have been wrong all this time (which is highly likely I am sure!), why is there oil splatter on the tappet cover, seemingly from oil 'blowing' out? Or is the answer that it goes both ways at different times?

 

 

Similarly, the diagram seems to show the oil emitted from my currently nude crankcase breather is redirected somehow to the intake. I thought I understood how this worked and now I am very confused! When I google image search 'l28 triple' (I do this a lot!) images of engines where this is hooked up are almost non-existent!

 

Regarding the crankcase breather I have seen setups where there's a hollow rod coming out of it, some with a filter on the end. I have also seen a larger filter mounted directly to the block.

 

But I want a sealed setup. That's why I got the manual out to begin with as I was interested to know if the breather at the top and the bottom could both be directed to the same place, one of those little ebay oil catch can jobbies - with a drain at the bottom to return oil to the system somehow.

 

I read this great article about how the oil flows through the engine and how the pressure effects that. They said that if there is a vacuum in the top it provides a better seal so I wanted my new setup to somehow replace that, however routing the breather in the tappet cover to a catch can will not replicate this vacuum effect. And if it is indeed beneficial, why does basically no one do it?

 

Please masters, guide me :-)

 

Lee

[dat2kman]

Dont overcomplicate.

Where is the 4" long bit of thin wall pipe that is supposed to stick out of the block?

 

When you get a bit of straight pipe shoved in, the nside end needs a couple of holes in the end, a piece of hose in an upward slope, to go into a metal catch can, use a rectangular olive oil can, spray paint it black, for secrecy.

And then run another hose from rocker cover breather, into can.

Then drill half dozen holes on top, to vent the lot.

 

Bring car, can, hose, bit of pipe clamps around, look at all mine to get idea, and fit yours.

 

You dont want it drained back in, it will have moisture condensation in it, the top breather is sucked into airfilter, the bottom breather goes into intake mani.

Dirty air, not good for engine.

 

The small ebay things, if you really want one, i have some here, are a bit small, and useless.

[Roberto]

The Haynes manual is correct.  Filtered air goes into the engine via the air filter box into rocker cover and comes out the block breather to a PCV valve where it is directed to the balance tube and burnt.

 

If you want yo keep a PCV system with triple webers, you need to tap into each of the runners to keep it even as there is no balance tube.  According to PMC, sealing of the rings with the negative pressure is not necessary and it can all be vented to the atmosphere. 

 

Get a catch can and plumb both rocker cover and block breathers to it and have it all vented so pressure does not accumulate.

 

Google images has tonnes of pics for mounting ideas. Apparently steel wool in the can helps oil vapours condense and stay in the can. As Dak2kman said, do not plumb back into engine.

[grimlynsan]

Thanks for feedback guys and for your offer Jason.

 

I want to create a simplified and pretty engine bay so am trying to avoid olive oil cans and whatnot.

 

So oil that comes out of either vent, if directed to a catch can, should NOT be recirculated back into the engine, I should just empty the catch can every now and then?

 

And if the vent on the tappet cover is sucking in air, does it matter that it is dirty air from a shared catch-can? Would it not be more optimal if the tappet cover vent was sucking from a separate can with a supply of clean air? Or does this make no bearing?

 

Thanks again,

 

Lee

 

 

 

 

[Roberto]

Yes empty the catch can when full.  Mine comes with a little plastic tube on the side which tells you the level.

 

The vent on the rocker cover ONLY sucks in air if the system is connected up with a PCV valve to the manifold.  Otherwise it will simply have oil and oil vapours come out.  That's why it can go to a catch can.

 

 

[grimlynsan]

Thanks for the comments guys. I have much to learn but am hoping the installation of a catch can and some aesthetically pleasing hoses is not beyond my DIY skills. I want to plan the whole thing before I buy any components so it has a complete look instead of looking like it was cobbled together from spares.

 

If you are in the mood, I have about a billion more questions! Well, as I'm no mechanic, they are more me guessing how things work based on years and years or forum reading and would appreciate if I have said something incorrect that you can correct me!

 

 

A)  Is this a fuel return line? I don't have one of these, but I like the idea of having the fuel continually circulating so it doesn't heat up.

 

B)  I note this doesn't have a filter. Is this a different type of setup to the catch can we have been talking about so far or are there holes in it I can't see?

 

C)  I imagine this hose must circle back on itself and go into the catch can. But what is the other hose? if it is the crank case breather they have camouflaged it nicely cause I can't see how it gets there!

 

D)  I beleive this to be vacuum from the manifold to the brake booster. Are there any other components that require vacuum in the engine?

 

E)  I really like this fuel rail!

 

F)  I think this is a pressure regulator. It ensures the carbies are not overfed. Is this correct? Where is the fuel pump? Is it in the tank?

 

G)  Looks like a fuel filter. connected directly to the pressure regulator. Mine is at the back, next to the tank.

 

H)  Looks like a dark hose coming out of the crankcase breather. I can't tell if it is going to the catch-can or somewhere else.

 

I)  There are two hoses here. I think one is this the continuation of the fuel return line and is directing fuel passing the carbs back to the tank. What is the other hose? I am guessing it is the fuel supply from the tank? Maybe connected to a fuel block out of vision as it seems very highly positioned... After sputtering at the end of the straight on my recent outing despite having plenty of fuel, I'd like to incorporate some kind of surge tank/fuel block into the design.

 

J)  There is no carbon canister. So where does vapour breather from the fuel tank go?

 

K) Is this the correct order?  Fuel tank with inbuilt pump -> surge tank -> regulator -> filter -> fuel rail -> carbies -> return line -> hard line back to tank

 

If my engine bay can look a fraction as good as this one I will be a happy man!

 

Thanks again all who take the time to put me right :-)

 

Lee

[bluerat]

Hey mate....how did you pass scrutineering without a catch can?

[dat2kman]

It wasn't a CAMS event!

They rely on the entrant to tick boxes on a form, and the assumption that being street registered, it is standard.

 

Lee, your list of queries/ideas/thoughts/on other engine bays, is a,,,,, comprehensive!

[grimlynsan]

Ha ha diplomatically put!

 

With so many conflicting opinions on all of these topics it's hard to know the best way to do things!

 

Lee

[PZG302]

Hey mate....how did you pass scrutineering without a catch can?

 

Street sprints don't need anything special for preparation of your car. My hairdresser car doesn't have a catch can and I don't need onefor the club days I do.

 

The event Lee did was also put on by a car club, so no scrutineering is undertaken.

[Clockwork]

*bump*

 

Curious about this thread, did you work out a solution in the end Lee?