Proper PCV arrangment for a 2L, A little help please Options

[North Coast Jim]

Have a newly rebuilt 2L in the car with 40 IDF Weber carbs which is running fine except for a RMS dripping oil. We believe we installed it correctly and took careful steps assembling the rest of the engine/flywheel/clutch/transmission. We believe that the crankcase vent system is not working properly which is pressurizing the crankcase as RPM builds, thereby pushing oil out the RMS.

My oil fill assy has a 022115542 PCV assy in it and a solid oil fill cap. I took the valve out to see if it was working. When I blow into the bottom it is initially open. Increased pressure it closes the valve. Seems backward to me. My oil fill tower has no vent in it.

I do know that when I got this motor, 6 years ago, the PCV assy was in pieces all captured in the oil fill assy. I took it out and reassembled it thinking it was correct. Maybe not ??

I have Len Hoffman heads when he sold them direct and the vents are capped shut per his instructions.

Any help is appreciated.

[914werke]

Lens suggestion (from that article) is in addition to capping the head vent lines also change the oil fill tower to the late version w/o the PVC & run a larger catch /vent line to a can

[North Coast Jim]

Lens suggestion (from that article) is in addition to capping the head vent lines also change the oil fill tower to the late version w/o the PVC & run a larger catch /vent line to a can

The direction I'm heading. Thanks

[JamesM]

We believe that the crankcase vent system is not working properly which is pressurizing the crankcase as RPM builds, thereby pushing oil out the RMS.

I suspect you are correct in that it is not working properly. This is something I have seen a lot, along with many many different ways of venting completely incorrectly.

the 72-74 motors especially with the head vents and oil tower valve can cause various issues when ran on anything other than the stock FI setup. The 022115542 valve is not a standard PCV valve and requires manifold vacuum to operate as intended (which even when operating as intended is not great) When that valve is used without manifold vacuum and with vents on the heads you will blow liquid oil out the head vent lines to the extent that you can eventually cause oil starvation and loose oil pressure. Removing that valve and running an open vent from the oil tower is a start. Doing that while capping the head vents is even better. Enlarging the vent at the oil tower (like they did on the 75 2.0s) is even better than that. Best of all I have found is then adding an actual PCV on to that enlarged vent.


So my preferred setup:
Plugged head vents
Modify oil tower for 19mm (3/4") open port
Add modern 19mm inline PCV (there is a cheap Awdi/VW part for this)
vent PCV to air filter

An additional special note, on the oil towers that originally came with 022115542 there is a hole cut that allows the installation of the valve. During engine operation THIS HOLE SHOULD NOT EXIST. The factory installed a plastic plug in this hole that at this point is missing on pretty much every car. On old more original cars you can sometimes find this plug sitting in the galley under the oil tower. It was installed for a reason. The oil tower itself acts as a baffle/separator that drops oil out of the airflow before it gets sucked into your intake. Where there is an open hole in the bottom of the oil tower directly under the vent line you loose this oil separation feature. Making matters worse is the distributor drive/cam gear flings liquid oil directly where this hole exists. End result, if this hole is not sealed is that at higher RPMs you are shooting liquid oil droplets directly into your crankcase vent airstream. This is where a lot of oil consumption issues come from. Modified tower or stock, seal this hole!

[emerygt350]

Interesting. I did not know this. Is that plug sold by anyone? Does it have a name?

[JamesM]

Interesting. I did not know this. Is that plug sold by anyone? Does it have a name?

It has a part number

022 115 486

The PET refers to it as "Stopper"

on Illustration 114-05 it is #9

I have to imagine that originally they were a softer plastic/rubber as all the ones I have found usually shatter when you try and reinsert them into the hole they fall out of.

I may have a picture around somewhere. Its basically a hole plug


That said when we modify the tower I just have them welded shut as there is no need to retain the hole if you are not using a replaceable valve

[JamesM]

I suspect people have found these before and had no idea what they were.

[emerygt350]

Now I need to find one....

[JamesM]

Now I need to find one....

Unless you are just looking to have every part on your car correct, if you plan on finding one for functional purposes it may not be worth the effort as like I said, the old plastic can shatter when you try to reinstall it. Also the fact at it probably already fell out isnt a good sign.

On my cars that dont have the hole welded up (because they still have a stock valve) I took a big piece of metallic tape and covered it up. I put the tape all the way across and under the gasket so it would be sandwiched in when installed for good measure. Actually did this as on one where I was able to get the plug in as well as insurance against it falling out.

I suspect you could find any appropriately sized hole plug and it could be made to work just as well, you just need to clearance one side of the plug that would overhang the edge if it were completely round.

[emerygt350]

Yeah, I just went to Lowe's to look at options. My concern on any plastic or rubber cap is the heat. I found some electric box plugs but I don't want to put metal in a spot where it could fall into the crank. I need to think on this....

[914werke]

I suspect people have found these before and had no idea what they were.

BINGO!

[JamesM]

Yeah, I just went to Lowe's to look at options. My concern on any plastic or rubber cap is the heat. I found some electric box plugs but I don't want to put metal in a spot where it could fall into the crank. I need to think on this....

The area where the plug falls into is pretty isolated from the rest of the motor which is why you can find the originals just sitting below if you remove the oil tower. But if it falls out at all then its pretty pointless anyways. This is why i just used the aluminum duct tape across the area.

[Dave_Darling]

One minor problem is that there is no "correct" PCV setup for a carbureted four-cylinder 914. US-spec cars did not come with carbs on them, and those were the ones with mandated PCV systems.

Your setup is aftermarket, and you or whoever you had convert it has to work out how to deal with the fumes and such.

--DD

[Ninja]

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)

And then...

A vacuum vented PCV system REALLY needs a plenum where all 4 cylinders are connected as ITB set ups usually have poor low speed vacuum.

It's the same reason a MAP sensor does not have the resolution to function properly below 2k RPM on an ITB set up.

Now, the HATED progressive 2bbl WOULD allow a vacuum PCV but...

[JamesM]

One minor problem is that there is no "correct" PCV setup for a carbureted four-cylinder 914. US-spec cars did not come with carbs on them, and those were the ones with mandated PCV systems.

Your setup is aftermarket, and you or whoever you had convert it has to work out how to deal with the fumes and such.

--DD

There is no factory correct way, but there are a lot of really wrong (see dysfunctional)
ways I have see people do it. Of course up Until the 1.8 all the factory approaches also had a level of dysfunction to them as well.


The most functional way for dual carbs, ITBs, whatever, is what I listed above.

No head ports/plugged head ports
3/4" from the oil tower, either modify or use one from a 75-76 2.0
Pop one of these bad boys inline (PN: 06A129101D)
Vent to one of the air cleaners

Using a proper valve gives a measurable improvement in crankcase pressure/vacuum over an open vent


this is at least the most functional while remaining simple way that I have come up with. If someone has a better way i would love to know about it.

[North Coast Jim]

Have a newly rebuilt 2L in the car with 40 IDF Weber carbs which is running fine except for a RMS dripping oil. We believe we installed it correctly and took careful steps assembling the rest of the engine/flywheel/clutch/transmission. We believe that the crankcase vent system is not working properly which is pressurizing the crankcase as RPM builds, thereby pushing oil out the RMS.

My oil fill assy has a 022115542 PCV assy in it and a solid oil fill cap. I took the valve out to see if it was working. When I blow into the bottom it is initially open. Increased pressure it closes the valve. Seems backward to me. My oil fill tower has no vent in it.

I do know that when I got this motor, 6 years ago, the PCV assy was in pieces all captured in the oil fill assy. I took it out and reassembled it thinking it was correct. Maybe not ??

I have Len Hoffman heads when he sold them direct and the vents are capped shut per his instructions.

Any help is appreciated.

Thanks all for the insight. Accumulating parts now