It's a little black cylinder located on the engine side of the firewall and has one hose connecting it to the check valve, which ultimately has a hose connecting to the vacuum pressure of the cylinder head. I broke the nozzle on the top off and then I kind of hot glued the vacuum tube onto the hole. Somehow it actually works. Anyway, does anyone know the function of this thing so I can figure out whether I need to replace it or not?

 

I think they used those (in older cars) to store pressure for vacuum powered accessories such as air conditioners, but I don't know for your car...

 

I would go ahead and replace it because chances are the jury-rig won't work for long. It just depends on what your car uses vacuum for. Some cars use it for HVAC, many use vac for brake boosters, and some for emission control devices. Save yourself a possible check engine light experience.

 

Well I'm wondering what it does because the brake booster and emissions devices already are hooked up to a vacuum source (the intake manifold)...I can't possibly understand what the vacuum tank does. On the vacuum diagram in my Helms, all it has is the line coming from the manifold to the vacuum tank but nothing coming off of it. So it's not even like it provides vacuum to anything.

 

Vacuum drops under high engine load, like going up a large hill, driving at high altitude, and rapid acceleration. Think of the tank as storage......When the engine is not producing much vacuum under load, the vacuum stored in tank still allows the devices that use manifold vacuum to operate. Emission control devices that run off of or are affected by manifold vacuum include EGR valve, carbon cannister, and PCV valve. A good insurance policy against having any issues with your emission control system is to make sure that there are no leaks anywhere. If it were my car, I would replace it.

 

Okay thanks, will do. Now I just need to find a dealership that knows wtf I'm talking about h:

 

From your description, it sounds like the charcoal cannister. This collect and stores vapors from you gas tank while the car isn't running to prevent them from beign released into the atmosphere. When the engine is running, The manifold vacuum draws air through the charcoal and sucks the vapor into the manifold to be burned.

Not a criticla component, but I's get the hose properly replaced. You'd fail an inspection without it and there is a very small risk of a fire since you could be venting a small amount of fuel vapors into the engine bay. Should be a cheap part to replace.

 

It says Vacuum Tank in the service manual, I don't think it's hooked up to the gas tank. But it might be, I haven't pulled it off yet. Good to know