For decades car manufacturers have made plastic radiator coolant overflow reservoirs in often weird shapes to fit against or around engine bay parts eg strut tower, wheel arch, firewall etc. This is no different for the Toyota Starlet which is mounted on the wheel arch in the engine bay.
As expected, this reservoir would not easily fit anywhere in the Mini engine bay so I had to make a custom tank. I measured the volume of the factory Starlet tank in the photo above, and between the LOW and FULL markings and it was 340mL. The expansion rate of coolant in a system is 6% and given the refill capacity of the entire Starlet coolant system is 4.8L (see http://www.datateck.com.au/lube/castr_au/), that equates to 288mL.
I had to find a spot in the increasingly crowded engine bay to fit a tank with a volume of approx 300mL. Such a small volume meant I could squeeze something in the triangular space between the airbox duct and inner guard... just.
I used some cardboard to prototype a tank shape/size which ended up as an irregular shape with a twist on one panel due to the profile of the inner guard. I then used some mild steel sheet for a second prototype. The steel tank allowed me to confirm the exact exterior tank dimensions and after applying some gutter sealant to cover/seal the edges (see photo below) I filled it with water to test the tank volume. The volume of the steel tank was 310mL.
For the final product, I used 2mm aluminium plate & 8mm OD tube from a local metal supplier and an aluminium weld-on filler (25mm inlet) from eBay. I don't have a TIG welder and after receiving a couple of expensive quotes to TIG everything together, I found a local guy who worked from home and was prepared to do the job for me for the standard Australian cost of a couple of cartons of beer. I supplied all the pre-cut pieces which he welded together. Two tabs were used for mounting the tank against the inner guard via a couple of rivnuts. Like the aluminium intercooler and radiator, I used some grommets to isolate the tank from the body to prevent galvanic corrosion of the tank.
There are two tubes at the bottom of the overflow tank. The overflow outlet on the radiator connects to the U-shaped tube (shaped to route around airbox feed duct) and this tube only projects a few mm into the bottom of the overflow tank, so it fills/empties from the bottom. The other short tube is for coolant overflow and actually runs the entire height inside of the tank, stopping ~5mm from the top so if the tank is too full, it simply dumps the coolant externally.
In this photo you can see the overflow tube just below the top of the tank.
A length of standard 8mm radiator overflow hose was used to connect the radiator to the overflow tank and another length of hose to run from the overflow tube to the bottom of the engine bay area for any potential overflow. My plan is to give the tank a light sand blast and etch/paint it black to match the anodised cap than was supplied with the weld-on filler.
As expected, this reservoir would not easily fit anywhere in the Mini engine bay so I had to make a custom tank. I measured the volume of the factory Starlet tank in the photo above, and between the LOW and FULL markings and it was 340mL. The expansion rate of coolant in a system is 6% and given the refill capacity of the entire Starlet coolant system is 4.8L (see http://www.datateck.com.au/lube/castr_au/), that equates to 288mL.
I had to find a spot in the increasingly crowded engine bay to fit a tank with a volume of approx 300mL. Such a small volume meant I could squeeze something in the triangular space between the airbox duct and inner guard... just.
I used some cardboard to prototype a tank shape/size which ended up as an irregular shape with a twist on one panel due to the profile of the inner guard. I then used some mild steel sheet for a second prototype. The steel tank allowed me to confirm the exact exterior tank dimensions and after applying some gutter sealant to cover/seal the edges (see photo below) I filled it with water to test the tank volume. The volume of the steel tank was 310mL.
For the final product, I used 2mm aluminium plate & 8mm OD tube from a local metal supplier and an aluminium weld-on filler (25mm inlet) from eBay. I don't have a TIG welder and after receiving a couple of expensive quotes to TIG everything together, I found a local guy who worked from home and was prepared to do the job for me for the standard Australian cost of a couple of cartons of beer. I supplied all the pre-cut pieces which he welded together. Two tabs were used for mounting the tank against the inner guard via a couple of rivnuts. Like the aluminium intercooler and radiator, I used some grommets to isolate the tank from the body to prevent galvanic corrosion of the tank.
There are two tubes at the bottom of the overflow tank. The overflow outlet on the radiator connects to the U-shaped tube (shaped to route around airbox feed duct) and this tube only projects a few mm into the bottom of the overflow tank, so it fills/empties from the bottom. The other short tube is for coolant overflow and actually runs the entire height inside of the tank, stopping ~5mm from the top so if the tank is too full, it simply dumps the coolant externally.
In this photo you can see the overflow tube just below the top of the tank.
A length of standard 8mm radiator overflow hose was used to connect the radiator to the overflow tank and another length of hose to run from the overflow tube to the bottom of the engine bay area for any potential overflow. My plan is to give the tank a light sand blast and etch/paint it black to match the anodised cap than was supplied with the weld-on filler.
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