[Vwdiesel] Crankcase ventilation / rotary vacuum pump

[Erik Lane]

The sump is vented through the valve cover. Previously with your
engine the hose to the block was air *into* the sump from the vacuum
pump. That air can then rise through the large drains in the head to
be vented out the valve cover and into the intake.

Venting it to atmosphere could leave you with a big oily mess in your
engine compartment. I would *not* recommend it. If you're at all
worried about sufficient venting then do as I said was a possibility
earlier with block to valve cover to intake all on one hose with one
tee in the middle.

On Thu, Jul 2, 2009 at 4:34 PM, Craig Osborn<cosborn at epix.net> wrote:
> Mark,
> Thanks for the advice.  I will remove the T fitting.
> From what I have read ventilation is needed so that the gaskets don't fail
> from the pressure.   Given the fact that this engine has around 200,000
> miles on it since the last rebuild and there is probably a fair amount of
> combustion gas getting by the rings, is there any additional value in
> venting the sump directly to the atmosphere instead of blanking it off?
>
> Craig
>
>
>> -----Original Message-----
>> From: mark shepherd [mailto:mark at shepher.fsnet.co.uk]
>> Sent: Thursday, July 02, 2009 6:27 PM
>> To: Craig Osborn
>> Subject: Re: [Vwdiesel] Crankcase ventilation / rotary vacuum pump
>>
>>
>> Blank off the sump ventilation and ventilate from the cam
>> cover only. Only
>> the brake servo/booster should attach to the vacc line [maybe
>> some small
>> control lines too eg a/c...]
>>
>> Mark
>> ----- Original Message -----
>> From: "Craig Osborn" <cosborn at epix.net>
>> To: <vwdiesel at vwfans.com>
>> Sent: Thursday, July 02, 2009 11:11 PM
>> Subject: [Vwdiesel] Crankcase ventilation / rotary vacuum pump
>>
>>
>> >
>> > I recently purchased a rotary vacuum pump that was advertised as a
>> > bolt on replacement for my old diaphragm type vacuum pump
>> on my 1981
>> > PU. When I started to install the pump I noticed that it
>> only had one
>> > hose fitting whereas the old diaphragm pump had two hose
>> fittings (one
>> > on the top that went to the brake servo, and one on the
>> side that went
>> > to the crankcase).
>> > I took the car around the block after hooking up the vacuum
>> hose to the
>> > top
>> > fitting without attaching the crankcase hose to anything
>> and I had the
>> > best
>> > braking power that I have had in years.
>> > I then called "Parts Place" to ask what to do about the crankcase
>> > ventilation hose and they said that many of their customers
>> were putting a
>> > T-fitting on the top and attaching both hoses this way.
>> When I did this,
>> > my
>> > braking power decreased markedly.
>> > I then took my old diaphragm pump and spun the gear and
>> noticed that it
>> > pulled a vacuum in the top hose fitting but put positive
>> pressure out of
>> > the
>> > bottom fitting where the hose would attach that would go to
>> the crankcase.
>> > Given this discovery, it seems as though the recommended T
>> fitting would
>> > not
>> > be the proper thing to do.
>> > Can anyone help me retrofit this pump properly on to my
>> 1981?  Maybe
>> > someone
>> > with a 1984 (when they started factory installing the
>> rotary pumps) can
>> > explain how their ventilation system is set up.
>> >
>> > Craig
>> >
>> > _______________________________________________
>> > Vwdiesel mailing list
>> > Vwdiesel at vwfans.com
>> http://www.audifans.com/mailman/listinfo/vwdiesel
>> >
>>
>>
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>
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