Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[ferretjuggler]

I got an alternator with a vacuum pump on the back of it so I can convert my CJ7 diesel to power brakes.
Trouble is there's an oil union on the vacuum pump and I really can't figure out how this works.
There's just a 1.25mm (aprox) metering hole into the body of the vacuum pump which has a rotor with slide out vanes.
Surely if I connect this up to the mail oil gallery on the engine it will just lose the lot (like all the oil in the engine)after a few miles.
Then I had the idea of plumbing the air outlet pipe back into the crankcase or rocker cover, so all the lost oil would end up back in the engine at least.
Then I got to think what would happen if I drove down a motorway for miles without using the brakes.
Wouldn't the pump just fill up with oil compleatly.
I dunno! There ain't many mechanical things I can't figure out but this has got me stumped.
Anyone know how it's s'posed to work???

[big g]

Erm No.........

But our lasses Pajero had an alternator which was linked to the oil coller radiator-might have something to do with that possibly.

[Dave69]

do you know what the alterantor is off ?

then take a look at how it was connected up in that vehicle

[ferretjuggler]

Erm...Nissan D21 pick up was it's original intended home I think.
I got another Nissan alternator kicking around which was a spare to the Nissan Patrol diesel I had a couple of years back.
That's got exactly the same system (slightly different pump) but it's a 24volt alt so I can't use it.
That one has about a 6" oil hose fitted to the pump (threaded unions each end.
Of course if I'd paid attention and examined everything properly when I removed it from the nissan engine, I wouldn't be in this mess now!

[dxmedia]

The oil in should be a brass fitting, this is a pressure oil line from the engine. Turbo feed should be ok?  The oil out will be probably a jubilee fitting and this should go back to the sump.

Don't worry about oil getting past the veins on the pump, they are air tight once they spin up. Only thing, if you can, turn the veins around so you have a nice sharp edge rather than the rounded one from thousands of miles of revolutions.

If there's multiple outlets on the pump (one small one fat), put a pipe on the ones you don't want and block with a screw or similar

[Bishops Finger]

You should be able to route the oil back to either the Vacuum pump or the engine via some sort of scav line


What make of vacuum pump is it???

[ferretjuggler]

Cheers guys.
The pump make is finest inscrutable Chinese copy of quality unit fitted to kokosan jap alternator (shipped in plain white box with no makers name!!!)
Oil fitting is actually a 10mm banjo bolt, but I take your point that it's a pressure fitting so will connect to a pressure oil feed.
I'm gonna route the vacuum pump exit (jubilee fitting)back to the sump somehow, the excess air that gets shoved into the crankcase will find it's way out of the breather with the blow-by gasses.
At present this exits via a separator unit then into a dump pipe over the front prop, but as this engine has done a fair milage and is "breathing" a bit, I'm planning an incest bypass to stuff it all into the air cleaner centre.

I asked the forklift mechanics at work about this today,(the oil feed to the vacuum pump) but the one kept insisting that it would fill the brake servo with oil.
I told him it was a VACUUM servo so the pipe sucks air out, not in,but he still couldn't see it
So much for professionals.