crankcase venting and oil burning was [Vwdiesel] turbo 1.6 ornon turbo advice

[Roger Brown]

Bart Wineland wrote:
> 
> Well I went out and checked as soon as I read this to be sure. My engine is
> from '86 but has a  older vacuum pump. It does vent back to the crankcase.
>  From the top of the pump is the vacuum line to the brake boost, a small
> yellow plastic line that heads for the dash for climate controls and has a
> third small hose that is hanging free.  I thought the third hose was
> plugged off but when I look at the "plug" it actually has a very small hole
> in the center? After looking at the set up I have to admit I don't
> understand how it all works. 

I would make sure that the plug is intact, should not have a hole in it.

> Wouldn't the output of the vacuum pump
> pressurize the crankcase? 

No, pressure out of the pump is probably no more that atmospheric.  It
can only grab air from the low pressure (vacuum) side and push that out
the other side.  

> How could that ever be good? Are you saying I
> could pull this line off the bottom of the vacuum pump and just tie it up
> to vent the crankcase to see if it helps my oil eating?

On my '81/LX pickup, the outlet of the vacuum pump went to the block.  I
re-plumbed that to add a pair of tee fittings to get the block vent up
to the valve cover vent.  I wanted to retain the stock plumbing.  If
your pump doesn't hook up to the block, leave it alone. I think that
having the pump connected to the block is not a good idea anyway.  Oil
mist from the block gets into the pump and rots the diaphram.  Also, if
you have any block pressure/blowby, that can damage the pump.  By
venting the block to the valve cover vent, you keep pressure from
building up anywhere in the system.  It worked well on my '81, but my
main concern was keeping pressure/oil out of the vacuum pump.  If I did
it again, I would probably do like I have on my '82 (1.9D w/ rotary
pump) and just have the block-valve_cover-intake vent like I do now.

-- 
   Roger