I have a crossflow with a Filler / Thermoswitch replacing the standard thermostat housing. The radiator has the normal cap but I fill from the filler over the thermostst housing as this is the highest point.
The problem is I fill it up to the top of the filler and after a couple of days the level is below the thermal switch level and the electric fan never comes on.

No leaks the problem is the coolant expands forces some out thru the cap and then the air replaces it when it cools.

Old escorts never had header tanks, but it looks like I need one here. I can see another problem in there does not seem to be anywhere higher than the thermostat housing available in the underbonnet area - does the header have to be at the highest point of the system?

- Cheers Alan

I don't know if this is of any help but here goes. The Cortina radiator (fitted to a Cortina) has a pressurised cap as normal and the overflow has a pipe going to a a plastic expansion tank fitted quite low down well below the top of the rad. This tank has a plastic lid through which the plastic pipe passed and the end of the pipe submerged in about half a tank of coolant. I never really understood how it worked with a pressure cap on the rad effectively sealing it off(unless it boiled) but it did the job. I had the same set-up on my Special and it never overheated and worked perfectly. Well worth a try I would of thought.

Please do let me know how you get on.

Regards

John

Mine doesn't have a header tank - fills up at the thermostat.

Same for me, no header.

Runs from pump to bottom of radiator, radiator to stat housing. No heater and no take off from inlet manifold.

I do have a small "collection" tank though. If the header cap opens to releave pressure, it goes into a small Mitsubishi header tank. Ive emptied a small cup full in the last 2 years.

HTH

I have an overflow tqnk from a Daewoo - engine gets hot, water overflows to the tank - engine gets cool, surplus water gets sucked back into the engine.

Dave Andrews describes it better here.
Works for me!

David

dont run a heade ron either the Caterost xflow or the avon xflow and both fine.
Mac

quote:

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Originally posted by David Jenkins
I have an overflow tqnk from a Daewoo - engine gets hot, water overflows to the tank - engine gets cool, surplus water gets sucked back into the engine.
David

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Never found the need for one myself. Although I see your point, my fan thermostat is in the side of the rad (Micra), so is never dry. The water level seems to drop slightly after I fill up, when it expands, but it finds its own level and stays there. I've been stuck in a traffic jam at 40°c in St. Tropez and it didn't overheat.

Mine uses an expansion bottle connected to the overflow pipe on the neck of the radiator.

The rad cap is in effect 2 valves in one. When the coolant expands it exits, as far as I can remember, by pushing the whole of the springloaded part of the cap upwards.

When the rad cools, the centre part of the spring loaded part of the rad cap lets air/coolant back in again. Otherwise the core of the rad would collapse.

I don't have room for a filler at the stat housing so just fill at the radiator. No matter how much its filled, after a run the level always stabilizes at about 20mm or so above the core of my MK2 Escort radiator.

When the engine is hot, the level in the expansion bottle can rise quite a bit, but once the engine cools again the level in the bottle falls back to normal. Works a treat!

Drew