Can anyone answer a very (probably) dumb question for me please....

Bought myself a new Polo rad that I want to fit. Thing is I don't really understand how a rad of this structure works.

I'd always assumed that the core was a continuous line of piping that 'zig-zagged' the length of the rad. What I find is that each of the core tubes starts/ends inside the boxes- you can feel the ends with a finger inserted in the inlet/outlet hole.

So, question is, with the inlet/outlet holes on the same side of the rad, what actually encourages the water along the core tubes?
Would the hot water not just be fed into the rad via the top hose, travel vertically downwards and be sucked out the bottom by the pump? All without actually passing along the core tubes which will contain 'cold' water.

I notice that the Golf rad has the fan switch at the bottom in the 'other' box than the inlet/outlet.

Or there something else going on inside the rad that I can't see/feel?

Thanks for educating someone who has significantly less brain cells this side of the weekend than the other.

James

There is usually a divide in the header tank so the water goes along say the top half and back along the bottom half

easy really

there are two header tanks, parallel to each other and small tubes connects each one like so:

||-----||
||-----||
||-----||
||-----||


where -- are the tubes in between;
|| is a header tank

in the olden days, the two tanks were horizontal, water entering the top one, cooling, would sink as denser thus forming a circulation (siphoning action).

later this is improved by means of a water pump; usaully is sucks water from the radiator to pump it into the block.

a lot of modern radiators have the header tanks on the side so horizontal instead of vertical fow through the radiator.

[Edited on 11/12/06 by 02GF74]

quote:

---

Originally posted by mookaloid
There is usually a divide in the header tank so the water goes along say the top half and back along the bottom half

easy really

---

It's funny you should mention that because I have just had the radiator delivered for my Mojo, and (after a bit of cross referencing) that turned out to be from a VW golf.

The inlet and outlet and fan switch recess/thread is on the same side, and it is designed to be installed with the cores horizontal, and the two end caps vertical. I wondered exactly the same thing, in that what forces the water through the cooling core when it is being pumped round?

Because the end caps are plastic (and are obviously injection moulded), if you look carefully on the end cap with the inlet/outlet ports in, you should be able to see a very feint "sink mark" where there is an internal wall (think of a baffle) that is moulded into the end cap. This is caused by a change in the wall thickness of the plastic, causing a greater linear shrink of the material, showing up as an area that has "sunk" in relation to the rest of the material.

On mine it is about halfway down the end cap. This wall causes the coolant to flow through the upper cores to the other end cap, down the other end cap, then back along the lower section of the cores, before reaching the outlet.

'tis cunning eh?!!

cheers
Andy

[Edited on 11/12/06 by bigandy]

Does it matter where the fan switch goes?

I notice that my Golf's radiator has it at the bottom on the opposite side from the inlet/outlet.

The Micra rad has it in the middle of one of the end boxes.

Cheers,
James

If you have some way of setting it, it can go anywhere. So long as it relates to the engine temp in some way then it can be set accordingly.

Where the switch goes depends on the switching temp of the switch --- it its near the top hose outlet from the engine you need a high temp switch (close to boiling point), if the switch is located near the cold outlet from the rad you need a lower temp switch.

BT,

I don't mind where it goes really, although into the bottom of the rad where the hole is seems easier/more efficient.

I see Westfield block that hole and fit it elsewhere. If I fitted it inline with the outlet by the thermostat on a Pinto what sort of temp would I want compared with fitting it in the bottom of the rad? Any idea?

Cheers,
James