Please explain how the vacuum tank on 3B works? (1 Viewer)

[Roberto]

Can someone please explain how the vacuum pump works on my 3B, how it routes to the small tank and then goes to the brake booster. My brakes are new, just replaced with new master cylinder, bleed them but brakes are still light and doesnt stop well? I am hoping i have the rubber hoses routed correctly to the tank on the underside that holds the air? Is it suppose to cause suction right where it goes into the booster?

Thanks
Rob

 

[amaurer]

Can someone please explain how the vacuum pump works on my 3B, how it routes to the small tank and then goes to the brake booster. My brakes are new, just replaced with new master cylinder, bleed them but brakes are still light and doesnt stop well? I am hoping i have the rubber hoses routed correctly to the tank on the underside that holds the air? Is it suppose to cause suction right where it goes into the booster?

Thanks
Rob

There is no magic in those lines (check valves, etc), any way you hook it up is probably going to work fine.

 

[cruiser_guy]

The vacuum tank is really no different than a compressed air tank on an air compressor. It's simply a reservoir.

 

[eleblanc]

Stop the truck and disconnect a hose on the tank or unscrew the drain and see if there is vaccum, you will hear air rushing in.

If that is ok, i guess you need to check into the brake booster.

 

[lostmarbles]

There is no magic in those lines (check valves, etc), any way you hook it up is probably going to work fine.

Not sure what you mean by this Drew.

There are two check valves - one is on the plastic fitting where the hose connects to the booster and the other is at the vacuum pump.

But I agree - It is hard to imagine anything being connected up wrong.



Edit:
PS. Basically, the vacuum pump just sucks air from your "vacuum tank/reservoir" and dumps it into your engine.

Putting your foot on your brake pedal releases air from one side of your booster-diaphragm into your vacuum reservoir and thereby makes "atmospheric pressure" (acting on the other side of the diaphragm) assist your foot pressure (in pressurising your brake hydraulic system).

 

[amaurer]

Not sure what you mean by this Drew.

There are two check valves - one is on the plastic fitting where the hose connects to the booster and the other is at the vacuum pump.

But I agree - It is hard to imagine anything being connected up wrong.



Edit:
PS. Basically, the vacuum pump just sucks air from your "vacuum tank/reservoir" and dumps it into your engine.

Putting your foot on your brake pedal releases air from one side of your booster-diaphragm into your vacuum reservoir and thereby makes "atmospheric pressure" (acting on the other side of the diaphragm) assist your foot pressure (in pressurising your brake hydraulic system).

Yeah good point, there are check valves at the pump and the booster, but I was trying to say that the vacuum line routing is nothing special. As long as the pump, reservoir, and booster are all hooked together, it doesn't matter if you connect the pump to the booster and the reservoir with a T, or if you connect the pump to the res. and then the res. to the booster. All the same.

 

[ToyRoverlander]

Does having a vac tank really makes a difference? I've got a bit of a hybrid vehicle and I want to put in a clutch assist to save my poor left knee.
Mine doesn't have a vac tank. Would adding one help with 'increasing vaccuum' when I add the clutch assist?
I'm sort of worried that the little pump won't be creating enough vaccuum to operate the brake and clutch often when offroad.

 

[lostmarbles]

Does having a vac tank really makes a difference? I've got a bit of a hybrid vehicle and I want to put in a clutch assist to save my poor left knee.
Mine doesn't have a vac tank. Would adding one help with 'increasing vaccuum' when I add the clutch assist?
I'm sort of worried that the little pump won't be creating enough vaccuum to operate the brake and clutch often when offroad.

I think "reservoir" is a better word than "tank" here because it really explains what the thing does.

At idle, I shouldn't imagine you'd have much "suck" from your vacuum pump compared to higher revvs.

And holding your vehicle (foot on the brake) on a slope when your engine has stalled is a time when reserve capacity must surely be useful!

BTW - My vacuum system holds good vacuum for weeks on end. I know this because the only time I hear my "low vacuum alarm" sound is when I'm bleeding my brakes (which of course involves pumping the brake pedal numerous times with the engine stopped.)

So if you're using a pump and booster similar to those used on BJ4# cruisers - I reckon it is a good idea to fit one. After all the Toyota design engineers must have found their reasons.

 

[ToyRoverlander]

Poor choice of words, my bad..

Sounds like your system holds a vacuum really well! I've never had much of a problem as long as I don't pump the brakes a lot, which I don't do cuz there's no need to! Discs allround rock! The clutch on the otherhand will be used more than the brakes.

Thanks for the input! I'll go and source myself a vac reservoir.

 

[lostmarbles]

Poor choice of words, my bad..

Sounds like your system holds a vacuum really well! I've never had much of a problem as long as I don't pump the brakes a lot, which I don't do cuz there's no need to! Discs allround rock! The clutch on the otherhand will be used more than the brakes.

Thanks for the input! I'll go and source myself a vac reservoir.

To be honest ...Despite what I just said ..I'm rather "in two minds about it".

After all .. petrol-engines don't have any vacuum reservoir as far as I know.

So please yourself whether you do or not. (I probably shouldn't have supplied any input at all.... I must be bored )

Maybe just see how you go with the vacuum-assisted clutch by itself first?

 

[Roberto]

thanks fellas, I just wanted sure if the tank was baffled or split inside and that the lines coming from alternator/ vacuum pump had to go to certain port on the resevoir but doesnt sound like it so I will pull lines off at booster and see if I am getting suction. When first installed before first rebuild blew it worked great but now not so much. On a good note new master cylinder from SOR worked great and so did the new volt regulator!!! Thanks!!!

Rob

 

[Awl_TEQ]

There is only a baffle inside to prevent the reservoir from collapsing. It is one chamber only. Roberto, if you will excuse the intrusion into your thread, I will soon be making a stainless reproduction vacuum reservoir and mounting bracket. Price unknown as of right now - back to your regular programming

 

[BreckenridgeCruiser]

Awl:

I'm interested in one... let me know when you get it finalized.

K
</hijack>

 

[Awl_TEQ]

The first two prototypes are being welded up today - I still need to work up a price and make the mounting bracket. Once they are done I'll post up in my "misc metal fab" thread in the storefront section (link in my sig)

 

[canucksafari]

You can also fab a bigger tank using an old fire extinguisher or similar tank.

 

[Awl_TEQ]

Any reservoir will do really. My reason for making mine like the original is that the first guy who asked for one does restorations and demanded it look like the original in size, shape, inlets etc. A reservoir like this type can be visualized like a bulge in the line - it just provides volume. I think if I used a fire extinguisher I would paint it black so no one tried to pull it off in an emergency - rig on its side - red cylinder bolted to the frame I can see some newb yarding on the thing trying to put out the flames

Good idea though

 

[Matt16]

To be honest ...Despite what I just said ..I'm rather "in two minds about it".

After all .. petrol-engines don't have any vacuum reservoir as far as I know.

So please yourself whether you do or not. (I probably shouldn't have supplied any input at all.... I must be bored )

Maybe just see how you go with the vacuum-assisted clutch by itself first?

Some gas vehicles have spherical vacuum bulbs. I think my 4Runner had one so you could engage 4wd (automatic disconnecting diff) while the engine was off. It was located in the passenger front wheel well.

 

[crushers]

hell, one guy used ABS pipe and caps to make up his and it worked real well... cheap too.

 

[canucksafari]

hell, one guy used ABS pipe and caps to make up his and it worked real well... cheap too.

Actually, not a bad idea but I think PVC would be less likely to become brittle. Use some rubber to insulate it from vibrations and it would probably last a long time. Its not like they have to hold 50lbs of vacuum.

 

[RufusTheDufus]

Sorry to bump up such an old topic but it seemed like an appropriate place to ask a question.

The 40 series diesels had a vacuum tank mounted to the frame under the body. Other diesel cruisers (and Toyota pickup trucks) used the little round tank under the hood.

My questions:
Is there a functional advantage of one style of tank over the other?

Is there a reason why the small round tank can't be used on a 40 series?