General PCV question

[mokoosh]

Hi,

Long time Vortexer, first time Dieselnetter. The Vortex diesel forum seems to be all but dead, so I'm moving over here.
You can see what I am driving and wrenching over there under my same name, this forum doesn't seem to want to let me give a link to my build thread.

Introductions done. Now the question:

What is the function of the lower crankcase vent on various models of VW diesel from MK1 1.6L to AAZ?

I was looking at an 82 Jetta that I just bought that still has the old style vacuum pump and I noticed that on that model the lower vent goes to the vacuum pump.

I see that an AAZ seems to have one that goes up to the PCV valve.

I have a 1.9L NA that seems to be most equivalent to an AAZ although there were no stock US applications. I use mostly MK1 peripherals from a 1.6L. My Longblock came with the lower crankase vent blocked off. I broke the PCV valve that came with the longblock years ago and replaced it with a used one, reportedly from a vanagon. I run Delo 15W40.

What has me interested is that I think i might have excessive pressure. I should go down to Harbor Freight and get a tester for $20, but haven't yet. Symptoms:

Intermediate shaft seal leaks intermittently even after being replaced twice. Not so much that I have to add oil between changes, but enough to make an annoying single drip where I park. (The lower vent seems to be right at the intermediate shaft location.)

Oil stains around my PCV to Air Intake connection on the intake side, no matter how tight the clamp.

So, since I never tire of messing with my Caddy, and can barely stop obsessing about it; I am thinking of going to the AAZ style PCV setup, but I thought I should ask for a bit more information about what it does and whether it could possibly be related to my leaks.

[ORCoaster]

You think you have excessive pressure?  Where in the oil lines themselves or inside the case?

If you have a good vent going from the top of the valve cover to the inlet of the engine then you probably are fine.  The use of the lower vent hole is somewhat suspect for me.  I think early on those vac pumps just needed a place to put their excess air.  Why not to the atmosphere?  Likely due to some oil in it as the pumps had that problem. 

On my Caddy I use one hose from the lower vent and Tee it into the upper hose just after the PCV.  I use an AAZ style on it as well. 

I have a hard time with pressure in the case building up.  I mean are there not holes for the oil to drip back into the oil pan that would also pass air to the upper valve cover?  So why two vents?  I think the original lower one was for keeping a long hose out of the system to the top of the valve cover.  They had a place available so they used it.  Once they went to the Vane style of vac pump the vent hole was excess and so they just put a cover on it.  That tells me it is not needed.  But if you don't have a cover or can make one then your hoses just need a tee back to the intake to burn whatever oil is in the air.

My two and a half cents. 

Oh and Welcome, we are much better than that other place you used to hang at.

[Dakotakid]

RE: your intermediate shaft leak.....did you install the little green spaghetti strap (like on yerr ol' lady's nightgown) o-ring in the seal holder.....not just the large seal?

Is your seal surface area on your int. shaft worn with a deep-ish grit/seal wear mark? I smooth-en those out with sand paper down to 2000 grit.

As for the belly-button vent: I still use those on all my engines and I simply run a hose up and over the top of the engine to vent to atmosphere. No, I am not a friend of Al Gore. And, no, I no longer loop those into the intake tract. if you do have blow-by, the intake will suck it up worse. After years of venting my blocks, I just automatically do it on all my rebuilds now and life is great. No, I do not have emission worries where I live.

If you still have an old diaphragm brake booster pump......send it to Al Gore and get a vane-style one. Or to Coaster....he is kinda Al Gorish.......

[mokoosh]

RE: your intermediate shaft leak.....did you install the little green spaghetti strap (like on yerr ol' lady's nightgown) o-ring in the seal holder.....not just the large seal?

Is your seal surface area on your int. shaft worn with a deep-ish grit/seal wear mark? I smooth-en those out with sand paper down to 2000 grit.

I have the Vane style vacuum pump on my 1.9L. I did not replace the green O-ring. I had one, but decided not to disassemble further. I assumed (I know) that since the oil was clearly coming from the center of the seal and not from the outside or the seal carrier, that the O-ring was OK. other assumptions include: my intermediate shaft is not worn because my motor only has around 50K miles on it and it did not look worn. On my second attempt at the seal I put it deeper in the carrier, just in case there was a groove.

I know this is a long shot, but I am willing to change over my PCV setup. I am not going to remove my timing belt again unless I have to for a few years. I will live with the drip if I must: 'From the earth it came, and to the earth it shall return'

[ORCoaster]

I didn't invent the Internet, but I sure use the byte out of it.  Had I invented it, it would have been much better secured.  I am a bit on the secure side.