New radiator - car overheating

12th December 2011, 14:34

My first big job

Just changed the leaking radiator in my car with a new one. All went well with the fitting and was quite pleased!

I put water into the radiator, then ran the engine with the water cap off for a bit whilst filling the radiator even more (so that there's no air in the system), then filled it with water and anti-freeze to the correct levels. Placed the cap back on, and went for a quick run. The water level is stable, showing no leaks.

Problem is that the car over-heats within 5 minutes. The fan kicks in fine when the temperature light comes on so that's not the problem. I'm guessing there's still a lot of air in the system, as the blower heater is ice cold. How do I get air out of the system?

Thanks!

12th December 2011, 14:41

Geraint, you need to refill it again without the engine on and undo the bleed screws! Then once everything has settled turn it on, leave for a few seconds then take off the bleed screws again.

Don't know if the 1.1 needs a header to bleed it properly... someone else will probably be in a better position to answer that - otherwise you'll end up constantly chasing bubbles!

12th December 2011, 14:55

Hmm. So what am I expected to find / do with un-doing the bleed screws when filling it up again? Sorry, not very mechanically experienced so I'm trying to do things myself with the car.

12th December 2011, 15:10

No probs. The cooling system is connected with pipes that go up and down within in the engine bay. The problem is you get air locks in places where the pipe directs flow upwards and then downwards again, air can pool at that position. At those points you have a screw that allows the air to be released from the pipe and therefore removes the pooling. Each saxo is different with regards to bleed screw points. For instance on my car (VTS) there is only two points, on others there are sometimes three. But generally the bleed points they have in common are:
1) Heater Matrix, this is where you get the hot air from in the cabin. In the engine bay there'll be two pipes going into the bulkhead, one is a feed in, the other is a return. And on one of those pipes will be a little bleed cap - you might have to follow them a bit until you've located it.
2) Thermostat, this is usually on the right of the engine if you're facing the front of the car looking back. On mine it's a metal screw.
3) Not on mine but I've seen some that are on the radiators.

Next to do it properly, you'll probably need a 'Header Tank', it's just a bottle you bung on to your filler cap. By keeping the header tank full of coolant, you're ensuring you've got the highest point on the system full of water, this makes sure that air is pushed out of the bleed screw points rather than being sucked in.

Do you have a Haynes Manual? That should point you in the right direction

12th December 2011, 17:03

Quote:

Originally Posted by Barry123

No probs. The cooling system is connected with pipes that go up and down within in the engine bay. The problem is you get air locks in places where the pipe directs flow upwards and then downwards again, air can pool at that position. At those points you have a screw that allows the air to be released from the pipe and therefore removes the pooling. Each saxo is different with regards to bleed screw points. For instance on my car (VTS) there is only two points, on others there are sometimes three. But generally the bleed points they have in common are:
1) Heater Matrix, this is where you get the hot air from in the cabin. In the engine bay there'll be two pipes going into the bulkhead, one is a feed in, the other is a return. And on one of those pipes will be a little bleed cap - you might have to follow them a bit until you've located it.
2) Thermostat, this is usually on the right of the engine if you're facing the front of the car looking back. On mine it's a metal screw.
3) Not on mine but I've seen some that are on the radiators.

Next to do it properly, you'll probably need a 'Header Tank', it's just a bottle you bung on to your filler cap. By keeping the header tank full of coolant, you're ensuring you've got the highest point on the system full of water, this makes sure that air is pushed out of the bleed screw points rather than being sucked in.

Do you have a Haynes Manual? That should point you in the right direction

I've got the Haynes manual and it does show me where the screws are, and I've located them since. That's a damn good write up, you've been an enormous help. I'll let you know how I get on with it!

I understand it all, apart from the header tank bit. I can get a bottle like you described, and like described in the Haynes manual - but what do you mean about keeping it full of coolant? I'm not too sure how the header tank works

Thanks once again, I really do appreciate it

12th December 2011, 17:21

cut the bottom of the plastic bottle off, put the screw top end into your radiator
make sure you have constant flow of water into your makeshift header with all bleed screws undone, once water is flowing out of all 3 , before you close them pour some coolant in, once its coming out same colour tighten all screws up

12th December 2011, 17:36

It's no problem at all, would be no point in the forum existing otherwise. I have a belt and braces approach to the coolant renewal, because I hate doing it so I don't like to repeat it because I've been to hasty first time around. Others will say you don't have to do certain things that I've mentioned but I'd rather list it all and then you can make up your own mind.

I've tried 2 ltr coke bottles the lot, but the best is those 4 pt tesco milk bottles - or you can buy the proper one from Citroen for like £18 or something.
The 'header tank' will consist of the 'top' of the bottle being turned upside down and slotted into the filler tank where you'll need to hold it during the bleeding process - I always grab my GF or father to aid me at this point.

Grab one of the 4 pt bottles and drink the milk, yum yum. Then once refreshed, cut the bottom of the bottle off and then pop the 'top' of the bottle on to the filler tank.

Now fill the filler tank and header tank will plenty of coolant and bit of water. Right up until the header tank can't fill any more. You'll have to press on the header quite firmly as coolant will spill out where they connect. I usually cover the joint with a rag to prevent it spraying about.

Undo the lowest bleed screw first, watch for bubbles and once the bubbles stop, replace the bleed screw - Caution though, you might find the bubbles stop and then as you're replacing the bleed screw more bubbles appears so take your time and don't worry too much about loss of coolant, just make sure the header tank is kept topped up throughout this process.

Then proceed to the next lowest bleed screw and do the same again - keep that header tank topped up.

Then the last one (if you have one).

Now, the annoying bit. You need to repeat the process with engine on. When the engine/coolant is cool, the thermostat is closed and directs the flow almost continuously around the engine, it's only when the temps get higher that the thermostat opens and coolant then flows to the radiator. The problem is that you can have air pockets in the auxiliary bits of the rad/engine system that you need to remove - hence why you have to have the fan turn on a couple of times as that signifies that the thermostat is fully open and flowing coolant from the engine to the rad.

So start her up and stick the engine into a fast idle of 2000 rpm. Wait for what seems like eternity. During this wait you'll notice bubbles appearing in the header tank from the filler, that'll be more coolant entering the system so make sure you keep the header topped up still.

Keep a feel on the rad periodically, it'll be cold for a while but as the thermo starts to open you'll feel it get gradually warmer and coolant flows into the rad system. Once the fan has kicked in a couple of times you can kill the engine, remove the header tank (watch out for the excess hot coolant as you do this because it WILL scold), pop the cap back on and go for a quick drive and see how the temps are looking.

Any probs, report back.

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12th December 2011, 20:46

Quote:

Originally Posted by Barry123

It's no problem at all, would be no point in the forum existing otherwise. I have a belt and braces approach to the coolant renewal, because I hate doing it so I don't like to repeat it because I've been to hasty first time around. Others will say you don't have to do certain things that I've mentioned but I'd rather list it all and then you can make up your own mind.

I've tried 2 ltr coke bottles the lot, but the best is those 4 pt tesco milk bottles - or you can buy the proper one from Citroen for like £18 or something.
The 'header tank' will consist of the 'top' of the bottle being turned upside down and slotted into the filler tank where you'll need to hold it during the bleeding process - I always grab my GF or father to aid me at this point.

Grab one of the 4 pt bottles and drink the milk, yum yum. Then once refreshed, cut the bottom of the bottle off and then pop the 'top' of the bottle on to the filler tank.

Now fill the filler tank and header tank will plenty of coolant and bit of water. Right up until the header tank can't fill any more. You'll have to press on the header quite firmly as coolant will spill out where they connect. I usually cover the joint with a rag to prevent it spraying about.

Undo the lowest bleed screw first, watch for bubbles and once the bubbles stop, replace the bleed screw - Caution though, you might find the bubbles stop and then as you're replacing the bleed screw more bubbles appears so take your time and don't worry too much about loss of coolant, just make sure the header tank is kept topped up throughout this process.

Then proceed to the next lowest bleed screw and do the same again - keep that header tank topped up.

Then the last one (if you have one).

Now, the annoying bit. You need to repeat the process with engine on. When the engine/coolant is cool, the thermostat is closed and directs the flow almost continuously around the engine, it's only when the temps get higher that the thermostat opens and coolant then flows to the radiator. The problem is that you can have air pockets in the auxiliary bits of the rad/engine system that you need to remove - hence why you have to have the fan turn on a couple of times as that signifies that the thermostat is fully open and flowing coolant from the engine to the rad.

So start her up and stick the engine into a fast idle of 2000 rpm. Wait for what seems like eternity. During this wait you'll notice bubbles appearing in the header tank from the filler, that'll be more coolant entering the system so make sure you keep the header topped up still.

Keep a feel on the rad periodically, it'll be cold for a while but as the thermo starts to open you'll feel it get gradually warmer and coolant flows into the rad system. Once the fan has kicked in a couple of times you can kill the engine, remove the header tank (watch out for the excess hot coolant as you do this because it WILL scold), pop the cap back on and go for a quick drive and see how the temps are looking.

Any probs, report back.

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That's perfect!! Thank you so much! I'll give it a crack tomorrow and I'll let you know how I get on. The only bit that confused me was that you were supposed to keep the header tank full. Well after you've bled the system and it's time to go for a drive, surely the water level needs to drop so it goes under the "MAX" mark? How would you do that if the header tank is full throughout? That's my only concern, but the rest is perfect!

Many thanks