Vacuum Pump Question

[81caddy]

I hope the pictures work.  This is my first time posting with pictures.

It is time to put the caddy back together and I don't know where these vacuum lines go.  Obviously one goes to the brake booster.  

If the picture works you can see where the red hose comes off the top of the vacuum pump.  The way it was routed when I obtained this project is the red hose went down to the fitting on the side of the block in the close up picture.  Then coming of the same fitting on the side of the block another hose went up to the intake manifold which also had the PCV valve t-fitted into the intake manifold as well.

Any help with this would be great.  Thank you...[/img]

[theman53]

I don't know but I think that is the piece I will need. I have heard that the piece on the block is what helps control blow by oil consumption on a new engine or one that is completely worn out. I am building a TD and want to break it in like this if this is what to do. I am just guessing, but someone on here will know for sure. I don't think you need that piece on the block at all. You could use a flat peice and block it off and plug your vacuum pump. Like I said it is just a guess.

[rabbitman]

That should work fine, I can't tell from your picture if you have the hose from the pump to the booster hooked up though.

[81caddy]

Thank you both for your responses.  The brake booster is hooked up correctly.  I just can't figure out what the other vacuum hoses do.  Why do you need vacuum that goes to the block and a hose from the block to the intake manifold?

[rabbitman]

I just can't figure out what the other vacuum hoses do. Why do you need vacuum that goes to the block and a hose from the block to the intake manifold?

I'm not sure why one goes to the intake mani, maybe it helps it breath better. As for the hose going to the block, the vacuum pump is moving air every time you push the brakes so it has to go somewere. Also, there's oil being pumped into the vacuum pump that normally drains into the oil pan through the bottom of the vac pump, Also if the diaphram ever rips all your oil would get pumped through the vac pump so it needs to vent into the oil pan.

[81caddy]

Do you think that the hose fromt the block to the intake manifold needs to be there.  It looks like the fitting on the side of the block that the hoses come out of may not be factory.  However, I don't know.  I can't find any information on this.  No pictures and nothing in the Bentley repair manual.

Thanks again for replying....

[rabbitman]

Do you think that the hose fromt the block to the intake manifold needs to be there.

No, I think you could take it off and be fine, but then you'd have to block off the extra holes.

[klr4evr]

My 82 Rabbit has a hose from the block connected to one side of the vacuum pump and the other to the brake booster. There is a single hose from the intake manifold to the valve cover. That 'T' fitting that is on yours has been added. Likely the same with the fitting on the block as mine only has one outlet.

Try and find a gear vacuum pump to replace the diaphragm type. My diaphragm pump seemed to eat diaphragms. Was fixing it twice a year until I got a gear pump. Now I never look at it.

[veedubcanuck]

On my engine it is like this.... The top line (suction) from the vacuum pump should go to your brake booster. then there should be a lower line (pressure) from the pump that goes to the fitting on the block. The line from the valve cover goes direct to the air box. If you have vacuum from the vacuum pump going thru your engine and also to your brake booster you would get no brake assist. (no vacuum)

[veedubcanuck]

On closer look, it just looks like the cover is mounted 90 deg. off on the pump and the vacuum port is on the right side instead of the top, so it looks right. From the looks of it all that was added is that line from the block to the top. Someone must have had issues with blow bye and that is what was done to equalize the pressure from the block.

[81caddy]

When blow by occurs isn't oil getting into the cylinders?  Not the other way around (combustion vapors into the block)......

[jtanguay]

When blow by occurs isn't oil getting into the cylinders?  Not the other way around (combustion vapors into the block)......

the pressure down below is enough to shoot the dipstick out of its tube...  :shock:

the system shown above will effectively eliminate this from ever happening... later 1.9's and TDI's incorporate this feature.  shame they skipped some of the 1.6's.  that could be some type of vent tube for the vacuum pump.  and also if its sucking from there, then at least its getting some oil vapours to help it last a bit longer.

[rabbitman]

When blow by occurs isn't oil getting into the cylinders? Not the other way around (combustion vapors into the block)......

No, blowby is caused by the combustion pressure leaking down past the rings, the breather is were the extra pressure gets out of the case. In the process oil mist/vapors/droplets gets carried with the air out of the valve cover port. The worse rings you got the more air/oil is gonna come out the breather.

[81caddy]

I guess my question should now be....Does the port on the top of the vacuum pump pull a vacuum?

Also I have never seen a breather on an engine block.  It makes sense  I just haven't seen one before.  It seems like a PCV system for the engine block.

[Turbinepowered]

I guess my question should now be....Does the port on the top of the vacuum pump pull a vacuum?

Also I have never seen a breather on an engine block.  It makes sense  I just haven't seen one before.  It seems like a PCV system for the engine block.

There should be two arrows cast into the cover beside or near the hoses that show you which direction air will flow through that port. Depending on how well the pump cover was realigned with the main body the top port may or may not be the suction port.

I've rebuilt a couple of these. They're very simple, really, but there are a relatively large number of parts that you need to keep track of.