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ZAP man

Vacum assist brakes

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Help! I have a 1959 I.H. school bus that I've converted into a limo/party bus.  Very cool bus indeed. The bus has vacuum assist brakes. Here's what I see under the hood. There are several tubes involved with this brake system and now I'm wondering if I need it to be so complicated because it looks like some of those tubes are part of a smog control system which this bus is exempt from having. Sorry, it's not the original motor. I think it's from a 60's I.H. vehicle. It's a 304 V8. There's check valves and pcv valves that are part of the smog system. There's also an oil bath air cleaner. So.....

First of all, I'd love to get rid of that oil bath air cleaner but it looks like it's part of the brake system. One tube runs from a valve cover up to the air cleaner with a pvc valve inline. Not worrying about the smog part I should be able to eliminate that tube. Yes? No? Then there's another tube going from the air cleaner down to a very large vacuum tank for the brakes. I'm wondering why. It seems like it just taking old air from the vacuum tank and dumping it back into the air cleaner. So I'm thinking that air can just dump anywhere. If I can get rid of those two hoses then I can get rid of the oil bath air cleaner. 

Now, another tube runs from my intake manifold down to the big vacuum tank. I believe that is where the vacuum assist comes in. But that same tube goes into a small block that branches two smaller tubes to the dash; one for the vacuum assist windshield wipers and the other to the vacuum gauge. My wipers don't seem to work that well when I accelerate and I'm thinking that I can go straight into the intake manifold instead of that block. I may need a check valve if I do. So in the end, I want to get rid of any wanna be smog stuff on the engine, get rid of the oil bath air cleaner and lastly,  make my windshield wipers work better. I hope I've explained this well enough. Thanks. ( I'm new here)

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Why get rid of the oil bath air cleaner? It works VERY WELL and lasts forever, unlike paper elements that need replacing at regular intervals. Even after paper elements were installed on regular cars, oil baths were available as extra cost options for  heavy duty applications. It is also usually LESS RESTRICTIVE than the paper element.

 

The block should just be a block of steel or brass with passages drilled in it. Unless it is cracked it should be fine and not your issue. Look for broken rubber lines and rusted out steel lines.

 

Also that vacuum tank should have a check valve to prevent loss of vacuum in the tank when you open the throttle. Maybe the check valve has gone bad. 

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The vacuum tank is a large reserve tank to supply extra needed vacuum for the frame mount brake booster and wipers when under a heavy load. Leave it.

The booster might have it's own fresh filter air intake or use the air cleaner for filtering intake air to the booster. The frame mount booster requires both fresh intake air and full checked intake manifold vacuum.

Leave the oil bath air cleaner as it is good at filtering air but also acts as a carb air intake silencer.  Drive that bus for a bit without the air cleaner and you will see how loud the carb sucking noise is going up a hill!!!! Really loud.

Get a factory service manual for your bus if you really want to understand how and why it operates.

Edited by c49er (see edit history)

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Another vote to keep the oil bath air cleaner. To service it, swish the filter in Varsol or cleaning solvent and let drip dry. Do not blow with compressed air, that can make channels in the filter medium. If the base is more than half full of dirt pour out the oil and clean it out with rags or cotton waste. Refill to the line with 50 motor oil. Pour a little oil over the filter medium and put it all together. There, you are done for at least 10,000 miles (unless you drive on very dusty roads or off road). At tuneup time check the reservoir, top up if necessary, clean and service if it is more than half full of dirt. On paved roads in a temperate climate you won't need to worry about it for years. One quart of 50 oil is a lifetime supply.

 The hose from the valve cover to the air filter is part of the PCV system. It feeds smoggy fumes from the engine into the intake where they will be burned harmlessly. The valve and hoses should be checked and cleaned at tuneup time and the valve replaced if it is worn or plugged up. Give it a shake, if it rattles it is still working. Not a bad idea to replace it every few years, they are not expensive. This type crankcase ventilation system was common on all cars with carburetors after 1963. They are generally trouble free and worth keeping.

The hose from the air cleaner to the reservoir is supplying clean filtered air to the brake booster. The other hose is the vacuum line getting vacuum from the engine.

The vacuum wiper motor may be worn or maybe it just needs to be lubricated. This is not hard to do, if you do a search you should come up with detailed instructions. If it still doesn't work, and the hoses are in good shape and it is getting good vacuum then either the motor is worn or maybe there are parts seizing up and causing too much friction. If the motor needs replaced, look around for a similar IH truck or bus with electric wipers and use that instead of the vacuum setup.

Don't be too quick to make changes. The engineers who designed your bus were not stupid, they did things for a reason. I learned long ago not to monkey with things I don't understand.It's MUCH better to fix things so they work as the factory intended.

Edited by Rusty_OToole (see edit history)
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