Hey all,

I seem to have a strange thing with coolant level in header tank, I sometimes find its about half way down the tank and the overflow is def filling up. The odd thing is though I've tested the spring on the Cusco 1.2 KG cap against (or is it 1.4?) the oe cap and it def takes more weight to compress which would mean stronger. The other thing is I've fitted a cooler thermo so temps aren;t going stupid (nor have they been anyway).

Anyone else got this with Cusco cap on 02 Scooby?

Seems like most or all coolant is filling up overflow tank, cant be 100% sure though as never checked level against level as not easy to empty my over flow as its a smaller tub by side of FMIC pipe.

 

Put the OE one back on and run it for a few days - if it cures the problem then the Cusco is faulty/not sealing.

Mick

 

you need to allow enough time for the engine to cool right down, only then can coolant ejected from the overflow be recouped (sucked up). Typically they run with the coolant level about 20mm below the neck of the header tank.

 

Wondered if it might be the seal, cheers Mick.

I didn't think the header can suck the fluid back up as when cools, cap shuts the side pipe? 20mm, think mine is trying to settle lower than that, certainly seems lower than when had 2L engine WRx. Its totally cool when i fill it up and/or empty the overflow tub. Might try the oe cap again for seal or just buy another 1.3 bar cap, cheers guys.

 

The whole point of the expansion/recovery tank is that it DOES allow the coolant system to recover a good deal of the fluid lost. if you brim it, and some coolany is lost, there will be a void filled with high pressure water vapour (steam), when the whole system cools right down, a vacuum is created and the header tank cap allows this to be equalised. The tube in the expansion bottle is designed to go below the fluid level, so when the coolant system sucks, it draws back the fluid.

It's not full proof, and a stronger cap will definitely reduce the amount of fluid recovered, but it does work.

 

Zen, you know everything bloke...

I'm gob smacked, didn't think it was possible with spring cap just pushing shut as it cools. Its just made me think my overflow tank has the tube sticking above the fluid level so it with suck air only. I'll fill it proper and see what happens.

Only other thing I've noticed is on refit of oe cap it gets real tight during the last 1/4 turn but the cusco flies on, has done from day one.

 

I see how it works now, the valve in the middle of the cap can be pulled open so when header cooling in vac mode, it opens and hopefully allows coolant to be sucked back in. I'll top up the overflow tank and see what happens. Also bent the guides on each side of the cusco so it sits firm on the header tank, tight at last 1/4 turn.