Xflow Expansion Tank

[IamScotticus]

OK, I'll plan on feeding my thirsty Xflow more coolant. 

 

Lots of guys who know a thing or two put them on thier lumps and the Europeans have been on the closed system for decades now.

 

Im not referring to a coolant overflow catch tank.  Thats an open system that recovers overflow by vacuum in the cooldown cycle.  Yes, my reluctant old school American but had to look it up too.

From what I understand,  a sealed system performs the same functions: maintains a system pressure,  retains excess, purges air, etc.  The main difference is the location of the pressure cap and the overflow tank must be at a high level.  A closed system has the venting pressure cap on the overflow tank.  The overflow is kept at the highest point and keeps an air space so it doesn't overflow.  Its probably less prone to evaporate loss too.

 

The closed system hook up is simple.  There is typically a primary connection between the bottom of the tank and some point in the lower coolant flow.  On a crossie that could be a T in the HWH line on the water pump.  The tank willl usually have a small barb or two for any top side bleed or overflow ports.  A typical one would be a standard radiator overflow barb in a thermostat housing.  

There isn't any critical flow science going on here.  The tank is basically an air collection point that holds pressure as well as coolant that ebbs in and out of.  There is an added benefit of the elimination of the old pressure cap return flow valve disc thing that should keep you awake wondering if its stuck. 

Thats one pesky failure point eliminated by just moving the pressure cap to the reservoir  end of the system.

 

So enuf selling the European system.  The question now is what tank for my American Iron (which wasn't born here but I'll claim it).   

 

If anyone has more than three buckets of old Caterham parts, chances are good there will be one of those Vauxhall (VX) kit tanks that bolt to the the two brackets on the forward cross brace.  I have one for some reason but I feel the hose route too exposed to the drive belt should it go slinging.  I would rather have something neatly mounted to the scuttle wall or a bellhousing bracket.  Regardless,  Im going for a smallish translucent plastic pressure unit with parallel vertical mounting tabs and a 16 lb pressure cap.  Currently looking through the Dorman catalogue.

 

Suggestions are very welcome but no fancy AN stuff.  Not racing.

 

 

 

Edited March 30, 2023 by IamScotticus

[MV8]

I've used this vw one. Most oem types need support beyond the flange. Here is how I did that. Flange is angle iron with 1x1/8 steel support strip. 

https://www.ebay.com/itm/185476356011?fits=Make%3AVolkswagen&hash=item2b2f4097ab:g:7xIAAOSwkWNitDOT&amdata=enc%3AAQAHAAAA4BuBk7vCNOe2CvVCuS5i%2B%2BpsfhEIKDyEQdKLnwkSlHrrh665d1yOBUwBa3x%2B6kxD1Z1voRKL5O%2Bj3%2Ff%2BToPkWSIpCh3ipInmfF%2FNwJ4qSjYupHDSS%2FdWqcoMdXI37Om6skiJtFEZIZROW5Zzm%2BVXCag2WHgQOrSDfUdc7iGYglwagFw9EYD4XxeJ9xmyO8NidwzE5OwSGealDJo9Qkku%2Bp8hndcc2zYWBlsk0LJH8izhPP2vlvaWNDKSwW86Me1E8HHy7dNnLBsU7nmYKMuHadpYO41IwShgzCE%2BXm00L5Zq%7Ctkp%3ABk9SR6C1pLnmYQ

[NSXguy]

The setup when I did mine. If you need, I have an extra thermostat housing with the take off to the header tank.