Attention Moderators: Can someone please raise my quota of stupid questions? I need to ask a few more.

1. I have a nasty oil leak that looks like it is coming from between the vacuum pump and PS pump. Is engine oil running through those parts?

2. Where is the exhaust port for the vacuum pump?

3. My vacuum pump seems to be getting weak. What is their normal service life?

 

I may not be of much help here, but here goes.

The answer to number 1 is. I don't think so.
(DOH! Edited to add, YES there is an oil line going TO the vacuum pump, but I don't seem to remember a RETURN line. Captive lubrication?)

From what I remember it's just a shaft with a lovejoy style connector on one end. No oil passes betwixt the two units. Mine was leaking slightly so I just undid the bolts connecting the two, used Brake cleaner to remove all oil, and applied liberal amounts of Permatex to both sides.
As of now, it has yet to leak again. But then again my truck don't get started all that often, much less driven.

Once again, glad I could be of No help to another DTR member!

 

The vacuum-pump and power-steering are gear-driven, riding piggy-back behind each other.

YES, they are oiled by engine oil, at least to the forward end of the power-steering pump.

The joint between the vacuum-pump and power-steering is a common leak point, due to neglecting to periodically check that the connecting bolts haven't vibrated loose.

When ignored too long, the gasket gets damaged.



If you have the superior double-diaphragm style pump, it exhausts through the center of the covers.

I don't know where the screw-type exhausts.



The double-diaphragm style will last several hundreds of thousands of miles.

After a long time, simply replace the diaphragm cap portion and go another half-a-million.

The later screw-type is much shorter lived.

I am not sure which year they changed.

My 89 has double-diaphragm and the 91.5 has screw-type.

Before jumping into changing your pump, install a vacuum-gauge.

A healthy pump should quickly, almost immediately, jump to above 23 inches Mercury, providing there are no leaks in the system.

Also, invest in a portable vacuum gauge ($7 at Harbor Freight) and check vacuum directly at the pump hose, then with all other lines connected.

Use the same gauge for both checks.

It should read the same at both connections.

If you show good vacuum directly at the pump, but poor vacuum when everything is connected, you have a leak somewhere.

The diaphragm inside the brake-booster is a common leak point.

 

The screw style exhaust through the crankcase. This is why it will appear like you have excessive blow by when the vacuum pumps or system is leaking. Oil return is also though the same area.

 

So, if after I check it and the pump turns out to be weak, do I want to get the early pump, or stick with the one for my year?

 

Explain this in detail for the mechanically challenged please?????
I also have a leak at the PS pump ..

 

Well this could explain alot on my truck.

With the things my truck is doing, leaking and what appears to be excessive blow by out the pipe, this post may have the answers to all my problems....

Thanks

 

Bearkiller was kidding (I hope). You want to keep the one you have and rebuild it yourself. fixinrams.com has everything you need.

A vacuum pump has to have somewhere to put the air it's drawing out of the vacuum lines. The rotary pumps we have exhaust that air into the timing case. If the vacuum system is in good condition, there isn't any exhaust air to speak of. But if you have a big leak, the vacuum pump is blowing a bunch of air into the timing case. All that air's gotta go somewhere, and the only place for it to go is out the breather tube. The excess pressure can also lead to oil leaks in other places.