Pressure tank cap - vented or not vented

[Gizmoman]

82 Westy, 1.9 AAZ TD.
I bought a new pressure tank as my old one had the smaller ports and I needed the larger ones to fit the new silicone hoses. Besides, the old tank was pretty cruddy inside - tried to clean it but nearly impossible to do.

The new one came with a new cap which has a small male hose port and my previous cap had none. I assume this ported cap is for a different application - any hints on which cap I should use and why?

[CRSMP5]

saying westy makes me think of bunny... and cap makes me think of gas caop...

the nippled rad cap on the vanagon... the nipple feeds the bottle behing the licence plate kinda like gm/honda do their resivor caps.. but i think it was gasser.. cannot rember its been at min 11 years since i saw one/worked on one..

[Gizmoman]

The vanagon radiator has no cap and this is the only tank there is. It's not behind the licence plate on this or later years.
I believe the stock cap (no hose port) may let air escape but not fluid

If I used the one with a hose bib I don't know where I would run the hose.
Maybe I just answered my own post.

[libbydiesel]

You should have a nipple on the expansion tank cap.  That nipple accepts a small hose that runs to the burp tank that is accessed by opening the license plate door.  All vanagons should have both tanks, and the hose between them. 

[Gizmoman]

You should have a nipple on the expansion tank cap.  That nipple accepts a small hose that runs to the burp tank that is accessed by opening the license plate door.  All vanagons should have both tanks, and the hose between them. 

That's odd my van didn't have a "burp tank" there's not even a bracket where one used to be. How did that even work? The original (when I bought it) setup was one tank and a solid cap.

I'll do some searching. . .

[CRSMP5]

well its a rad cap to me on a vw.. the pre overflow bottle caps same till 88ish... thyen vanagon got nipple so it was like honda/gm suck out of tank that had no pressure system..

libby wrong too.. i know of some that had none back there.. but they lacked 2 grills up front.. chough aircooled.. chough...

but for some reason i think some watercooled lacked it too.. but the bottle bracklet is bolted to the heatsheild above the muffler.. not the rear paned by plate..

[Gizmoman]

Having it by the licence plate certainly makes sense and if I add one, I'll try to mount it there.
I did some searching and found this. . .

What I don't understand is how did it work without one?
Also, the tank pictured in the link has a port on the bottom. I'm assuming the one on the top is for the small hose from my pressure cap from the expansion tank. What would the bottom one go to?

[burn_your_money]

Ill start by saying I know nothing about vans.

If that was a J/G the lower port goes to a hose that connects to the metal coolant distribution pipe around the engine. The top one runs to a port on the top of the rad. I think it's purpose is to assist in bleeding the rad as it usually has a restricter in it.

[CRSMP5]

thats not it.. thats 88+ style bottle... for mk2/thru mk5..

what your seeing is a squarish type of bottle with flapper lid, kinda like washer bottle that just snaps onto it..  and 1 nipple..

the idea is the cap you have will suck or push fluid into a unpresurized tank like gm/toyota... so it can be checked hot or cold... and added too also..

[Gizmoman]

thats not it.. thats 88+ style bottle... for mk2/thru mk5..

what your seeing is a squarish type of bottle with flapper lid, kinda like washer bottle that just snaps onto it..  and 1 nipple..

the idea is the cap you have will suck or push fluid into a unpresurized tank like gm/toyota... so it can be checked hot or cold... and added too also..

OK, so there should be no other ports on it other than the one small one which I believe would have a hose going from it - to the bottom of the tank. When the system cools down there is vacuum created from the expansion tank which sucks coolant back into the system.

Is that right?

If so, I could probably get one of those generic units at the local FLAPS.

[libbydiesel]

The '82 diesel vanagon version is NLA and has been for quite a few years.  You can still get and use the later version:

http://www.van-cafe.com/home/van/page_277_231/reservoir_-_overflow_reservoir.html

Because of the coolant flow path, if there is air in the system, then when running it moves to the top of the expansion tank.  When coolant system pressure exceeds the 14-15psi of the pressure cap, it vents to the hose and to the burp tank.  If there has been any air in the system, it is burped out.  When there is no air in the system, then coolant is moved to the burp tank.  When the system cools off and pressure drops, coolant is drawn back into the system.  The burp tank itself has the one hose barb.  It is open to atmosphere at the top of the tank (there are little vent holes).  You could replace it with any container you wish.  I suppose you could just use the single tank with the understanding that there will always be air at the top when cold.  Checking the coolant level would be a lot more difficult and require emptying the rear hatch area.   

[CRSMP5]

id try to get what libby linked for ease of access... but yes any generic gm style overflow bottle will work.. but does it fit and get to easy??

air in vanagon system bad from my experiances.. the whole cooling system is overly complex due to stuff like this.. but letting air get into the rad.. having to pull the grill to get to its bleeder and such.. you really need the silly top off bottle by the plate..

[Gizmoman]

Thanks for the replies and the link.
I bought a simple tank from the FLAPS for 8 bucks that will fit nicely by the licence plate. The cap (actually the tank as well) is pretty cheezy but I'll bend up a nice aluminum mount and get it installed.

Ideally I'd get the Van Cafe tank but 45 bucks and I still need to buy a cap
Wonder of my original cap (without the nipple) would fit.

EDIT:
Van Cafe lists the cap for 8 bucks - it's out of stock

Maybe that's a sign that I should use the 8 dollar jobby

[CRSMP5]

just rember what its doing.. or at least what its used for.. if it works great.. if it does not.. then buy vanagon one.. but the idea libby spoke of real nice..

[Gizmoman]

just rember what its doing.. or at least what its used for.. if it works great.. if it does not.. then buy vanagon one.. but the idea libby spoke of real nice..

I sent Van Cafe a request for the cap and when they will have one.