j.kenzie@sbcglobal.net

Thanks, Carl. I measure crankcase vacuum through dipstick tube at 5-7 inches Hg. That seems fine to me. The noise is kind of a howl. Maybe the PCV valve is acting like a small mouthpiece on a trumpet and creating the sound.
I also tightened my oil filler cap and my crankcase vacuum went from 2 up to the present 5-7 in. Perhaps that will change the dynamics and modify the sound.
As usual I might have just not done something correct, or misinterpreted something.
As long as the sound is innocent, I can live with it.
Thanks,
Dave

Carl Fausett

If you suspect the PCV valve, remove it temporarily and insert a straight piece of tubing in its place. Let me know if the noise changes or is eliminated this way.

j.kenzie@sbcglobal.net

Thanks, Carl. I will give it a try this weekend.
Dave

j.kenzie@sbcglobal.net

Ok, I'm still working on this, but I have some data. I replaced the PCV valve with tubing and no change in the noise. Return line to plenum clamped: no noise; return line open: noise. I tried partially clamping it and there is a threshold where the sound goes away. I decided to measure crankcase pressure through the dipstick tube to investigate, and what happened? The sound stopped as soon as I pulled the dipstick. My conclusion: I have too much crankcase vacuum?
I don't really have a known source of fresh air intake to crankcase. I could drive with the dipstick loose, but I was thinking of one of those cam cover vents by K&N that you stick in.
I don't know how to tune the amount of fresh air, but that was just an idea.
Thanks for helping,
Dave

77tony

Post a video with sound ? T

Carl Fausett

Make sure that it is what you think - and that air is going IN your dipstick tube at idle and not OUT. It would be much more likely to have some crankcase pressure, rather than vacuum.

j.kenzie@sbcglobal.net

Hi guys,
Carl was very helpful and sent me a cam cover vent fitting that I attached to a 1/2" ball valve and a stainless steel mesh filter. I put the tube from my Mityvac into my dipstick tube and measured crankcase vaccum at warm idle (1000 RPM) with the vent ope, closed and half way in between. I got 6" vacuum with no vent, 2" with my vent line open and 4" vacuum with the vent halfway open. My ringing, howling noises go away with the vent open halfway or more. I leave it at halfway to keep my crankcase vacuum at 4".
Here's some pics of the readings and the vent layout.
Thanks,
Dave

j.kenzie@sbcglobal.net

Not letting me post pictures. Will try again later.
Dave

j.kenzie@sbcglobal.net

Hi guys,
Just to complete my project. Here is a picture of my cam cover vent. I added a ball valve, and normally keep it about half open. That gives me an inch or so of crankcase vacuum, and no noise.
Dave

RedRaider1

Dave,

Thanks for the update with details and the time on the phone this morning. Running into the same situation with my install. I've reached out to Carl now as well.

SeanR

I've been tossing this set up around, in my head, for several weeks now and I really can't see any logical thinking that has gone in to it. Carls design is to take one of the cam carrier plugs out of the cam carrier, put a nipple on that and a hose, attach the hose to a Y that also connects to the oil filler breather hose, then route the bottom of that Y to a long hose that snakes around to the intake (drivers side) intake suction. I really wish I had taken pictures of this as some of you will be as amused as the people who stopped by to see the progress.

After talking to Myles on Friday, I can tell that there really has been no prior thought put in.

I asked three times if he and Carl thought it was a good idea to run total vacuum (18 or so HG) on the crank case at idle. I got the same response all three times.

"people put vacuum pumps on cars all the time"

Yes they do, but when you add a vacuum pump it is progressive. The pump is NOT pulling 18hg on the crankcase at idle, it's progressive. Little to NOTHING at idle and as the RPM's go up, then it starts pulling pressure out of the crankcase. What this "kit" is doing is pulling vacuum on the crankcase at the same rate that is in the intake manifold. Now who the fck thinks this is a good idea?

What makes it worse is, under boost you have a check valve that keeps the boost from entering the crankcase via the same route that the suction is coming from. Great idea, except you get getting ZERO pressure relief under boost. So if you are going full tilt down the highway/racetrack/moms driveway what do you suppose is going to happen to those front or rear main seals? They blow out.

Now if you are going for a quick run..........flooring it then letting off, then the crankcase pressure isn't going to build much and as soon as the BOV opens, you will start to suck out crankcase pressure, exactly when you don't need it.

The "Fix" appears to be opening another spot on the cam carrier to atmosphere so that when you are at idle, you are sucking in outside air to the case, then in to the intake. But under boost you are just shooting the pressures out through that one spot.

One fun thing for this set up is that after the car has been running and the oil is shot up and in to the "oil separator" as the vacuum leaves the crankcase it makes for some funny bubbling sounds as it all interacts.

Lizard928

While it is unlikely to cause any damage to run high vacuum in the crankcase at lower RPMs, it will do no real good either.......

But as the OP has been told to remove the PCV valve and run it straight connected to the intake, that means that if the intake is pressurized, so is the crankcase...... I've seen front main seals pop out from pressure on other cars, and have seen reports on this happening on 928s as well.

As Sean says it is true as well, if there is no other opening in to the crankcase, the system will build pressure while under boost. If you are under full boost for 1 minute, you will build a HUGE amount of pressure, and good bye seal.

Now another unintended consequence, if you don't have a perfect seal on the crankcase (which you don't from the whistle), then you are pulling in unmetered air and your AFR will go lean.
Then look at it under boost, you now have a boost leak, and your AFR will go pig rich with little control......

All in all, this wreaks of disaster......

Carl Fausett

The quickest "fix" is to go racer on the install, and evacuate the crankcase fumes to a catch can with a breather on top.

But, for our street kit, we kept the PCV system in place are vacuuming the crankcase fumes into the intake manifold to be re-burned, OEM-style.

Sean, I understand you were not able to finish the intercooler installation anyway, so the customer is bringing the car here for that and a 6-speed install. I can sort this out when it gets here.

What John McKenzie did was simply to put a control valve on the cam tower to limit the amount of vacuum in the crankcase at idle. That stopped his whistling.

Petza914

Carl, so what setup will I have on my Stage 2 kit that you're wrapping up? Thanks.

Carl Fausett

For those reading, here are two pictures that may help your understanding. These pictures are L-Jet specific and do not apply to K-Jet or LH-Jet.

In picture LOC1 I show the stock PCV evacuation from the top of the oil separator and where it draws into the base of the intake shoe.

First, because the stock oil separator is good but not great at removing missive oil from the air flow, we supply parts that go witihin the oil separator to make it more effective. As you know, the oil that is removed by the oil separator is allowed to drop back to the oil pan by the drop tube from the bottom of the oil separator to the front and top of the oil pan (16v cars only).

But, we like to install yet another oil drop to prevent ingesting liquid oil into the intake.

That is what Sean is referring to. Picture LOC4 shows a tee we supply and a 1/2" drain is added into the 16v cam cover.

The crankcase gases with missive oil droplets comes out of the top of the oil separator, and as it passes by our tight 90-degree turn the gases go left and the oil droplets tend to continue straight because of their mass (inertia). The gas, now as clean of missive oil as we can get it, is routed around to the center plenum to be ingested. Oil dropped in to the cam tower continues to the crankcase in the normal fashion.

On a race car, the driver may do some engine braking (manual transmission assumed) and he can really draw a high vacuum and pull some oil up into the top of the engine that a street driven car would never see. Then the long hose that Sean routed around to the intake is instead routed to a simple catch-can. The catch can is vented to atmosphere.

John McKenzie's test of pressures seen at the dipstick tube prove it is working well. Even though supercharged, he still draws a vacuum at idle (which helpos the rings seal, and the engine make all available HP).

If John could have driven the car with his pressure gauge on the dipstick tube to monitor crankcase pressure, he would see a near-zero pressure condition at all partial throttle points. Under WOT and max load, he would slowly see the crankcase become slightly pressurized by red-line, and immediately return to zero pressure the moment he lifts out of the throttle.

As very little time is actually spent at WOT, max load and red-line; and because the pressure is immediately evacuated; this is of no concern.