Crankcase Breathing

[vw505]

I am thinking of some idea's for my DLI blower motor and was thinking i could use a vac line off the carb hooked into the carb to pull vac on the case.

[Piledriver]

The same basic setup will work, you only need a SLIGHT vacuum (but one that can "keep up") to make a HUGE difference in oil leakage and consumption.

The pile (T4/1700) has ~3-400K miles on it (original) and used to leak like a submarine with a screen door and burn a bit of oil too... It now uses virtually NO oil. (perhaps a quart between changes at ~6-10K miles)

I consider it the ~perfect test subject for EGR experiments, as it is pretty much "worst case" for an engine that is still worth running. It probably simulates a loosely set up race motor fairly well as to blowby.

Currently running Brad Penn 20W-50 as it is freaking HOT in Dallas this summer...
Usually ran 5-40 Rotella, having to reconsider that now that it's reformulated to CJ-4. (NOT backward compatible to CI rating, like API SM to anything before) Perhaps I'll just add some GM EOS...

The setup I'm playing with on my "new" 86 Cabriolet is basically as described from the factory: I have added a Cheby EGR (AIR pump) check valve in the big line, and have a small line going to the TB side of the CIS air meter, has a small pressure drop, ~3 in WC at idle, a bit more under load.

The big check valve is in case of situations where there IS case pressure, and is currently connected to the std air cleaner location. (Other side of air meter would be better...)

The Pile runs a better setup currently: single Cheby AIR pump check valve (a Krankvent would work better) to the post air meter side, and the slight vacuum sort of acts as a "dc bias" on a diode and allows the check valve to operate w/o backpressure/more efficiently--- the 3-5" WC vacuum level keeps it open vs atmosphere, except when the case has vacuum pulses, pressure exits easily. I want to do that on the cabby, but it doesn't have a suitable place to plumb it yet. The case runs 3-5" WC vacuum levels, measured at the dipstick tube.

The Pile has some woven pot scrubbers in the breather tower, the Wabbit draws its PCV air above a "windage" tray over the cam under the valve cover, both setups keep oil out of the flow well.

Ultimately, (for both setups) I really want to stick a vacuum regulator for the "purge" line so I have a small regulated case vacuum level to aid ring seal etc, perhaps 3-5" Hg. Much more than that you have to look at reversing the crank/FW seals, as they make screaming noises under 10-12" Hg case vacuum ... They weren't designed to stop pressure getting IN.

Keeping the crank seals from wearing out and sucking dirt into the engine is a long term worry at higher vacuum levels as well, and they are likely to wear out much faster, as they don't get as much oil. Probably >~2-3" Hg vacuum in the case would be "race only" due to this , IMHO.

[SiQDiZ]

So basicly the KrankVent valve is a one way valve, lets air out of the crankcase, but doesn't let air in. I don't understand why the KV is so much different from other brand PCV valves from different OEM manufacturers. I mean, on the KV website they state that the KV is made of superiour quality. Is an OEM branded PCV short lived on a ACVW engine?

[FJCamper]

KrankVent vs PCV

Yes, the Krankvent is a one-way valve, but from my own research a far cut above a common PCV valve.

PCV valves are built for specific engine applications, and are low cost disposable items. They are prone to clogging and valve or spring flutter.

The KrankVent is a real race item, and performs at high RPM without flutter, not to mention having a decent self-cleaning ability.

And you pay well for it compared to a PCV. But you cannot wear it out.

FJC

[Bugfuel]

Normal PCV valves are a joke. They are nothing but a tube with a captive ball/puck inside. No spring. You shake them, they rattle. Mounted in the correct position on the valve cover of the vehicle they are intended for, allows them to work somewhat consistently. Still, they are not reliable one-way valves.

[funkSoulP]

Interesting topic. I've been experimenting a bit myself some years ago with one-way valves. I did not know about the KrankVents, only noticed the pulsating airflow when the oil filler cap was of.

I used some ghetto engineering stuff to try it out on one engine - and it worked. I took a reed valve from a 50cc Suzuki 2-stroke engine and placed it on an old BlingBling filler neck. Below is a picture of the initial tests with the reed valve in open air so the principle is clear. The complete reed valve shown is 10€ when bought new.

The valve is more effective is it can be provided with a large surface area, like the filler neck. I eventually mounted it in a can and drilled a small hole below the valve. The hole allows oil mist to drain back into the crank case. And just for the record, I'm also a fan of stainless steel pads

Reed valve proto

[Scabbyfab]

I eventually mounted it in a can and drilled a small hole below the valve. The hole allows oil mist to drain back into the crank case.

Reed valve proto

Very interesting concept. do you have a photo of the completed assembly on the car?

[BonesTheRipper]

When using the Dual KrankVents on a type 1 engine, is the dumpcan necessary or can the can be bypassed and the line ran to the sump for oil recirculation?

[Piledriver]

When using the Dual KrankVents on a type 1 engine, is the dumpcan necessary or can the can be bypassed and the line ran to the sump for oil recirculation?

I get a lot of water in my catch tank... (Which is connected to manifold vacuum via a tiny diphram type check valve, the case lives under ~50-70 KPA manifold vac almost all the time, the 1L tank is a damper and something easily drained with a sight tube)

My MAIN dump hose with the larger valve goes to the air cleaner (but it could easly go to another catch tank) I have never seen any evidence it's opening. (it's still dry/clear)

Since I use the scrub pads, the amount of lost oil is pretty minimal, at least on my DD.

I'm totally diggin the reed valve setup... That's basically what a Krankvent is, conceptually.
Any case vacuum measurements?

[karol]

Hi

Anyone used an idea, of using deep sump, and fill oil to a lowest dipstick level, or even lower - to reduce oil mist inside case? Is it safe considering that amount of (oil located mostly in extra sump not case) is still greater than factory 2,5 liters?

[Piledriver]

Hi

Anyone used an idea, of using deep sump, and fill oil to a lowest dipstick level, or even lower - to reduce oil mist inside case? Is it safe considering that amount of (oil located mostly in extra sump not case) is still greater than factory 2,5 liters?

The oil mist is being tossed off the crank/rods/pistons etc, the actual oil level is below the cam/lifter boss area, which acts as sort of a natural windage tray... so I'm dubious lowering the oil level further would be of great benefit.
However---A shallow deep sump is probably a good idea on any hipo T1 just to increase oil capacity/reserve, as ~1 quart ends up in the 3/4 side rocker box at high revs unless you do some tricks.

Good PCV flow control can help this... Put a purge air "leak" hose (w/<1mm restriction) from an air filter to the 3/4 side... and "suck" on the case or 1/2 side.. The purge air will keep 3/4 rocker box from filling up. NEVER suck on the 3/4 side for obvious reasons.

A large deep sump is a rock/speed bump magnet .

[r1cpowdercoating]

I realize that this is an old post but just realized what the SS pads act as. They are acting as a coaleser filter. a coaleser acts in a way that oil mist hits the SS pads and allows the oil to accumilate and eventually drain back into the case while allowing the "air" to pass through. This "cleans" the "air" up as it is pushed out.

Ron

[Steve Arndt]

My "Copper" pads are rusting. Where can I find real SS (stainless steel) scrubbers?

I had three chore boys in my CB oil filler/breather. It was a bit crowded, I'm going to go down to just two, with a small air space between them.

[Piledriver]

I realize that this is an old post but just realized what the SS pads act as. They are acting as a coaleser filter. a coaleser acts in a way that oil mist hits the SS pads and allows the oil to accumilate and eventually drain back into the case while allowing the "air" to pass through. This "cleans" the "air" up as it is pushed out.

Ron

You betcha.

It could also be visualized as a selective filter/labyrinth seal of sorts, gases/water vapor get through easily, but oil droplets normally hit something, stick, collect and drain back, a bit like like an oil bath air filter. The more you stuff in, the better it works as long as it doesn't restrict airflow.
(You would probably have to cram them in pretty insanely to overpack, they be springy and push right back)

My "Copper" pads are rusting. Where can I find real SS (stainless steel) scrubbers?

I had three chore boys in my CB oil filler/breather. It was a bit crowded, I'm going to go down to just two, with a small air space between them.

I have not had any issues with the SS ones, even the generics.
They did not work for me in an external breather box, too much vaseline due to lack of heat.

My Chore boys did the same, i wouldn't call it rust it was green copper corrosion, but they were probably really made of copper back then.
Now it's too expensive. The woven SS ones have been in there for YEARS now. (I used to take them out and look at them on oil changes, now I just take a peek when pouring oil back in, no problems ever)

The "trick" is I stuff them in the breather tower, so they stay HOT. and they stay very clean/don't load up with Vaseline.
On a T1 the equivalent would be inside the gen tower.
This greatly helps keep the oil in the engine.

If you put them somewhere not engine block heated, they'll still work well, but expect vaseline build up, they will need regular cleaning.

[andy198712]

you can buy such a vent for KTM's probably cheaper too...