Discussion
Hi
I'm after ideas. Recentally my S has been loosing some coolant if the engine is hot and the fan running when I switch off. The temperature climbs and a smallish amount of coolant is ejected via the overflow. If I switch off obviously the fan stops but then if I turn the ignition on the fan resumes (engine not started) and if I switch off when the fan stops, only a couple of minutes or so, no overflow.
The question is should I rewire the fan to the live circuit cutting out the ignition switch? Is there any downside in doing this?
I'm after ideas. Recentally my S has been loosing some coolant if the engine is hot and the fan running when I switch off. The temperature climbs and a smallish amount of coolant is ejected via the overflow. If I switch off obviously the fan stops but then if I turn the ignition on the fan resumes (engine not started) and if I switch off when the fan stops, only a couple of minutes or so, no overflow.
The question is should I rewire the fan to the live circuit cutting out the ignition switch? Is there any downside in doing this?
Hi Norman,
I have thought of doing the same but was concerned that there is always the risk of flattening the battery if there is a fault with the temp sensor so I just leave the ignition on until the fan stops.
Not being an electical bod though perhaps there is a better solution than just bypassing the ignition switch
I have thought of doing the same but was concerned that there is always the risk of flattening the battery if there is a fault with the temp sensor so I just leave the ignition on until the fan stops.
Not being an electical bod though perhaps there is a better solution than just bypassing the ignition switch
hi, the engine temp will always rise for a few seconds on any engine when it is switched off.
Whether the fan is on or not is not a problem because it would only be cooling the water in the radiator (water pump stationary)not the engine.
You're small water loss is caused by the water expansion in the radiator(due to rising temp) when the fan is not running. If you leave the coolant level alone this will get to the point where it will find its optimum level and no longer leak.
so quite simply just switch off and walk away.
sphs2
Whether the fan is on or not is not a problem because it would only be cooling the water in the radiator (water pump stationary)not the engine.
You're small water loss is caused by the water expansion in the radiator(due to rising temp) when the fan is not running. If you leave the coolant level alone this will get to the point where it will find its optimum level and no longer leak.
so quite simply just switch off and walk away.
sphs2
Roy C said:
What level is the overflow bottle running at? Most V6 S's run well below the level on the (Fiesta) bottle (some nearly empty), otherwise the extra fluid will be ejected in just the way you describe.
Not sure if the same problem but for the first 3 months i over filled from the swirl tank.Car let out water everytime i pulled up.
Then filled to a lower level. Ever since, no excess water, water level the same for the past 3 years !
(If this is the wrong answer i`ll get my coat
)I agree with Mr Cliford. I had the water ejection problem as I was over filling. Got to a level the engine was happy with and it has stayed there.
UNTIL last night and the thermostatic switch didn't kick in and the header tank started whistling to me. So I will have an over ride switch on this week end and check out the thermostatic switch. I think the over ride circuit was covered in Steve Heaths S book.
UNTIL last night and the thermostatic switch didn't kick in and the header tank started whistling to me. So I will have an over ride switch on this week end and check out the thermostatic switch. I think the over ride circuit was covered in Steve Heaths S book.
Well been out to check
Water level in expansion tank maybe about 1/8th full (new sealing cap a few months ago)
Swirl Pot full (new pressure cap a few months ago)
Checked for air locks, none I could find
Checked bleed screw on rad no air trapped.
Hmmmmmmmmmmmmm????
Wait and see i suppose.
Has anyone connected the fans to the live circuit??
How many have fitted overide switch for the fan, is fo any issues?
Water level in expansion tank maybe about 1/8th full (new sealing cap a few months ago)
Swirl Pot full (new pressure cap a few months ago)
Checked for air locks, none I could find
Checked bleed screw on rad no air trapped.
Hmmmmmmmmmmmmm????
Wait and see i suppose.
Has anyone connected the fans to the live circuit??
How many have fitted overide switch for the fan, is fo any issues?
Edited by Gerald-TVR on Wednesday 16th July 14:06
Hello Norman
I fitted a variable temp fan controller in the top hose...you can get the fan to come in anywhere between about 50 and 120. Mine comes in just as the needle reaches 90..works a treat and the way I wired it also keeps the old switch as a back up (the one in the top hose pipe)
Mine was losing water when I got it...found it to be the filler neck in the swirl pot had a few holes where it mated to the swirl tank..soldered it up, fitted the correct cap, and never loses a drop now.
hope that helps
Ant
I fitted a variable temp fan controller in the top hose...you can get the fan to come in anywhere between about 50 and 120. Mine comes in just as the needle reaches 90..works a treat and the way I wired it also keeps the old switch as a back up (the one in the top hose pipe)
Mine was losing water when I got it...found it to be the filler neck in the swirl pot had a few holes where it mated to the swirl tank..soldered it up, fitted the correct cap, and never loses a drop now.
hope that helps
Ant
Norman when you fitted the new pressure cap did you transfer the old rubber washer (aka a bit of inner tube) from inside the cap of the old one to the new one?
There is a one way valve in the cap - when the water cools on a standard installation it allows air in, but with the additional rubber washer in the cap the theory is that it is forced to suck water back in through the overflow instead.
I'm not sure in reality that it really works as well as intended.
You haven't got a leaky rad have you?
Mine was leaking before I took it apart, only a slight leak but the evidence of crystalline deposits from the antifreeze was there - look at the bottom corners of your rad.
Chris
There is a one way valve in the cap - when the water cools on a standard installation it allows air in, but with the additional rubber washer in the cap the theory is that it is forced to suck water back in through the overflow instead.
I'm not sure in reality that it really works as well as intended.
You haven't got a leaky rad have you?
Mine was leaking before I took it apart, only a slight leak but the evidence of crystalline deposits from the antifreeze was there - look at the bottom corners of your rad.
Chris
Gerald-TVR said:
How many have fitted overide switch for the fan, is fo any issues?
I fitted an over-ride switch but have never needed to use it in anger... like others I saw some fluid loss when I filled the swirl tank to the limit, but now dont fill her right to the top (just below the tank top) and dont see any loss.I also found that if you go to Halfrauds there are pressure caps with seals in the box and by transferring these to the box you want you end up with a proper seal and not some old inner tube jobbie...
K
Thanks Guys
There is the proper seal on the pressure cap replaced by Adrian Venn so its the correct one. Chris surprisingly it seems to work fine except as outlined above. I did have a slight rad leak but its fine after using Barrs Leaks I intend to get rad sorted shortly.
Kevin have you been a naught boy then??
There is the proper seal on the pressure cap replaced by Adrian Venn so its the correct one. Chris surprisingly it seems to work fine except as outlined above. I did have a slight rad leak but its fine after using Barrs Leaks I intend to get rad sorted shortly.
Kevin have you been a naught boy then??
it was just a hypothetical thought 
Gerald-TVR said:
Well been out to check
Water level in expansion tank maybe about 1/8th full (new sealing cap a few months ago)
Swirl Pot full (new pressure cap a few months ago)
Checked for air locks, none I could find
Checked bleed screw on rad no air trapped.
Hmmmmmmmmmmmmm????
Wait and see i suppose.
Has anyone connected the fans to the live circuit??
How many have fitted overide switch for the fan, is fo any issues?
`Swirl pot full` eh !Water level in expansion tank maybe about 1/8th full (new sealing cap a few months ago)
Swirl Pot full (new pressure cap a few months ago)
Checked for air locks, none I could find
Checked bleed screw on rad no air trapped.
Hmmmmmmmmmmmmm????
Wait and see i suppose.
Has anyone connected the fans to the live circuit??
How many have fitted overide switch for the fan, is fo any issues?
Edited by Gerald-TVR on Wednesday 16th July 14:06
Thats what i did and it always overflowed.... now the level is 5/6/ inches below from the top
and its remained that way for three years !
Sounds like the problem to me !!
Edited by Mr Clifford on Wednesday 16th July 17:58
Hi Norman,
I think there may be some confusion over terminology in some of the above posts. To clarify - the steel cylinder near the radiator is normally referred to as the swirl pot/tank, and the plastic bottle near the brake/clutch master cylinders is the usually called the expansion bottle/tank. Assuming you've got the caps on correctly (sprung pressure cap on the swirl pot and plain cap on the expansion tank), the expansion tank is simply that, and not part of the cooling system. It is not pressurised because the overflow pipe vents it directly to atmosphere, and the cap doesn't need to seal - it's only there to keep the flies out.
My S3 cooling system seems to work correctly - it fills the expansion tank when hot and sucks the coolant back into the swirl pot when it cools. The swirl pot is always full to the brim, because any air in the system which finds its way into the swirl pot is displaced into the expansion tank when hot, and replaced by coolant sucked back on cooling. My expansion tank has a constant level no more than one quarter full when cold - any extra soon gets blown out.
You say you have a new pressure cap, but are you sure it seats well? Or even the right one? Check the swirl tank filler neck and polish the outer seat with a bit of emery if unsure. If the outer seal doesn't seal properly you will readily expel coolant into the expansion tank when hot, but suck in air past the cap on cooling. This air will happily disperse around the system on the next run, so more coolant goes out as it warms up. And so on.
Having said all that, I think you're just overfilling. Leave it alone and you may find that one eighth full is the correct level for your car.
Steve Heath's book explains all this and much more, by the way.
Regads,
Graham
I think there may be some confusion over terminology in some of the above posts. To clarify - the steel cylinder near the radiator is normally referred to as the swirl pot/tank, and the plastic bottle near the brake/clutch master cylinders is the usually called the expansion bottle/tank. Assuming you've got the caps on correctly (sprung pressure cap on the swirl pot and plain cap on the expansion tank), the expansion tank is simply that, and not part of the cooling system. It is not pressurised because the overflow pipe vents it directly to atmosphere, and the cap doesn't need to seal - it's only there to keep the flies out.
My S3 cooling system seems to work correctly - it fills the expansion tank when hot and sucks the coolant back into the swirl pot when it cools. The swirl pot is always full to the brim, because any air in the system which finds its way into the swirl pot is displaced into the expansion tank when hot, and replaced by coolant sucked back on cooling. My expansion tank has a constant level no more than one quarter full when cold - any extra soon gets blown out.
You say you have a new pressure cap, but are you sure it seats well? Or even the right one? Check the swirl tank filler neck and polish the outer seat with a bit of emery if unsure. If the outer seal doesn't seal properly you will readily expel coolant into the expansion tank when hot, but suck in air past the cap on cooling. This air will happily disperse around the system on the next run, so more coolant goes out as it warms up. And so on.
Having said all that, I think you're just overfilling. Leave it alone and you may find that one eighth full is the correct level for your car.
Steve Heath's book explains all this and much more, by the way.
Regads,
Graham
Hi Graham
Yep mine is set up OK exactly as the bible, plain cap on expansion tank, long neck pressure cap on swirl pot. Any water loss is via overflow from expansion tank.
I'm just going to leave all that alone and see if it sorts itself out.
Still begs the question on the fan, would it be a good idea or not to connect to non switched supply.
I'll keep you all informed of progress.
Yep mine is set up OK exactly as the bible, plain cap on expansion tank, long neck pressure cap on swirl pot. Any water loss is via overflow from expansion tank.
I'm just going to leave all that alone and see if it sorts itself out.
Still begs the question on the fan, would it be a good idea or not to connect to non switched supply.
I'll keep you all informed of progress.
Gerald-TVR said:
Still begs the question on the fan, would it be a good idea or not to connect to non switched supply.
I'll keep you all informed of progress.
I personally would opt for a "Delay Off Timer" this would allow the fan to run on for a few minutes after the ignition is switched off, they are usually variable so you could set it low and keep increasing the time untill you reach your required time. I'll keep you all informed of progress.
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