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Billy Dean

posted on 31st Oct 11 at 15:54

Yeah, I don't really want to loosen the hose from underneath for the reason you've given!

How on earth did you loosen the 'bottom' rad hose from above then??
(The power steering reservoir is in the way!)


posted on 31st Oct 11 at 15:28

It'll probably be fine yes, but personally, id do it properly.

If you're worried about threading the switch, just remove the whole rad, clean it out then put it back in and fill it with coolant.

I removed all hoses from the top so no need to get underneath as you'll get soaking wet!

[Edited on 31-10-2011 by johnhara1]

Billy Dean

posted on 31st Oct 11 at 14:37

Yeah, that's what I'm worried about!
I don't want to throw more time and money on this car. I could do without buying a new rad and all the associated labour time.

I'm now thinking if I can get 2 litres out from removing the top hose, and at least a further 1 litre from removing the so-called 'bottom' hose then that would mean there would be only 2.8 litres of water left in the system.
I could flush it through for good measure and then simply top up with 3 litres of neat coolant to achieve the 50:50 mix.
Good idea? ;)

p.s. what's the best way to access the 'bottom' hose? :)


posted on 31st Oct 11 at 14:05

I had the same problem on my last corsa, it had been threaded so couldn't remove the switch and it just spun and spun but it didn't leak.

In this case, i just removed the whole rad! ran a hose through it, put it back in then new coolant.

Billy Dean

posted on 31st Oct 11 at 14:00

I've bought 3 litres of Vauxhall red longlife coolant ;)
The whole system is 5.8 litres (according to Haynes). So I've got the right amount for a 50:50 mix.

The only thing making me worried about removing the Cooling Fan Switch now is the risk of cross-threading. I've read on here how a number of people experience the switch just spinning around indicating the thread has been damaged.
Are there any tips to avoid this risk?


posted on 31st Oct 11 at 13:48

If you're going to do it, do it properly mate. It'll be minus 10 degrees soon.

You want proper coolant and anti freeze, not water.

Oh and yes, it's easier from the bottom as it's tight at the top.

Billy Dean

posted on 31st Oct 11 at 13:29

Thanks for your replies, guys.

I have an adjustable spanner/wrench somewhere in my toolbox so I may attempt to loosen/tighten it with that. It looks a lot bigger than 22mm but I spose the adjustable will take care of it :)

Just to clarify...the only way to get a good turn on it is to loosen it from underneath the car, right?
(I did try to access it from above with the top pipe removed but it was fairly tight with no room to swing a spanner!).
Also, the rad bottom pipe is a pain to get to anyway - the power steering reservoir is right in the way!

Update: I just had to top up the coolant reservoir with another litre of water (no leaks since yesterday). Sooo, removing the top pipe alone discharges about 2 litres from the system.
If I haven't got time I may just top up with 2 litres of antifreeze and drive around with a 35:65 antifreeze/water ratio. Good idea? ;)


posted on 31st Oct 11 at 12:32

I removed the fan switch to flush mine as like you said, the bottom rad hose is a few inches away from the bottom. I just used a adjustable spanner to take it out then stuck the hose pipe in the header tank.

[Edited on 31-10-2011 by Jamie-C]


posted on 31st Oct 11 at 12:30

iirc it's a 22mm spanner on the fan switch as you're correct, there's no "bottom" hose.

If it's not 22mm, i must have used an adjustable as it's big :lol:

You wont get a socket on it, as the connector is wider than the socket at the top so if wont go over.

Billy Dean

posted on 31st Oct 11 at 12:26

Thanks for replying.

I asked the questions I asked due to the guidance in the Haynes manual, and after reading related posts on here.
To be honest, I'm open to suggestion because I am new to this engine.

I would like to flush out as much of the cooling system as I can because it's been running on 100% water only for the last 6 months and I reckon it might be well grubbed up inside.

They say you have to remove the Cooling Fan Switch to properly drain the rad,
as the so-called 'bottom pipe' on th rad is only about 2 inches lower than the top pipe!

I agree with you that you don't have to remove every drop of water, but I want to remove as much water as I can if it's easy to do so. I pulled the top hose off yesterday and it only needed a top up of 1 litre. So there is approx. 4.8 litres left in the system. I reckon if I drain the rad I can flush out another 2 litres. So that leaves about 2.8 litres in the engine block. If it's a tough job to remove the stat I will have to leave the stat in place. But as long as I've drained out as much of the easy stuff I'll be happy.

I just need to know the socket size of the Cooling Fan Switch.
And if the bleed screw is a useful way of draining part of the block.
And if the stat removal is a ballache of a job.
Anyone know for certain? :S


posted on 31st Oct 11 at 02:00

1. No idea but I'm sure you won't need it off.
2. You might mean the water pump. Thermostat is on the left side of the front of the engine with the big S-shaped radiator pipe going on to it.

3. Probably, but you don't need to. You can take off the radiator hoses and you'll get throughput of water. You don't need to remove every single bit of old water.

Billy Dean

Icon depicting mood of post posted on 31st Oct 11 at 01:14

Engine: X14XE (Corsa B 1.4 16v).

I've finally got some time now to attend to my engine coolant, which is currently made up of 100% water and no antifreeze :!
I intend to drain as much of the water out, flush the system, and then top up with a 50:50 mixture, or greater.

I have a few questions I was wondering if you guys could help me with:

1. What size socket/spanner fits on the Cooling Fan Switch? It looks massive - around 35mm??
2. Is it true that to remove the thermostat (to drain the engine block) you have to remove the timing belt??
3. As an easier alternative to the above, can a significant part of the engine block be drained by simply unscrewing the thermostat housing bleed screw?

Many thanks.