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Thanks for your reply.
Bearing in mind I've not used the car for 5 months, and having filled the reservoir up to minimum level with coolant, I'm now worried that coolant may 'expand' and pump from the radiator when running back up to normal temperature?
Will this be an issue?
Reading around, it seems that the coolant expands/contracts when heated/cooled.
Should I be worried when I go for my next drive?
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With the car on level ground and a cold engine , top up the coolant to the max mark on the expansion tank . Use a 50/50 mix of antifreeze and water . Just monitor the level over the next few days/ weeks .
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Which engine is fitted to your Fiesta? If the 1.0 there are known issues with the degas pipe - if so get it investigated straight away and you may have ducked a bullet
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Will this be an issue?
No.
Reading around, it seems that the coolant expands/contracts when heated/cooled.
No more so than the water level in your kettle does between cold and about to boil
Should I be worried when I go for my next drive?
No - as long as the coolant and oil levels are somewhere between the min and max marks. But, as said, you clearly have a leak - hopefully not into one of the cylinders.
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But, as said, you clearly have a leak - hopefully not into one of the cylinders.
Thats probably not very likely, BUT IF it happened it would be likely to wreck your engine on startup, due to hydrolock.
If you want to guard against (and detect) this (remote but catastrophic) possibility, take the plugs out and turn the engine over on the starter before running it normally..
I recently did this on a Honda Accord after decoking the EGR path with brake fluid, and found this had got into cylinder number 4. Due to the deeply recessed plugs (I'm used to older cars without this feature) simply turning it over didn't get it all out. I should probably have swabbed or syringed at TDC.
If you've already run it without any alarming bangs or thumps you dont have to worry about this particular longshot.
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Bearing in mind I've not used the car for 5 months, and having filled the reservoir up to minimum level with coolant, I'm now worried that coolant may 'expand' and pump from the radiator when running back up to normal temperature?
If you have only filled to the minimum level there should be nothing to worry about. Even if you fill to maximum there should be space for the coolant to expand into, and even then there is allowance for overflow without damage. I can't think of a way for coolant to disappear while the car is not used, if it is otherwise driveable without overheating.
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Sorry that I've not had the opportunity to reply until now - really appreciate the further comments.
I think the engine is a 1.2L.
So there is absolutely no way, having sat idle for the past five months (some of which in very hot weather), that if there has been any contraction of the coolant into the radiator (if any) that that would have resulted in an empty reservoir? If I've understood correctly, the most expansion / contraction is likely to be minimal and not litres?
I think there's about a litre of space above the maximum line.
So the general consensus is that it will be safe for me to operate without worrying the radiator / pump / tank to blow due to the coolant 'expanding' once it reaches / heats to operating temps?
Thanks again
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Sorry that I've not had the opportunity to reply until now - really appreciate the further comments.
I think the engine is a 1.2L.
So there is absolutely no way, having sat idle for the past five months (some of which in very hot weather), that if there has been any contraction of the coolant into the radiator (if any) that that would have resulted in an empty reservoir? If I've understood correctly, the most expansion / contraction is likely to be minimal and not litres?
I think there's about a litre of space above the maximum line.
So the general consensus is that it will be safe for me to operate without worrying the radiator / pump / tank to blow due to the coolant 'expanding' once it reaches / heats to operating temps?
Thanks again
You don't need to worry about the expansion - but you DO need to worry about the leak so further investigation is needed.
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So there is absolutely no way, having sat idle for the past five months (some of which in very hot weather), that if there has been any contraction of the coolant into the radiator (if any) that that would have resulted in an empty reservoir? If I've understood correctly, the most expansion / contraction is likely to be minimal and not litres?
Liquids are incompressible, so there will be no 'contraction'. One possibility is that after a complete coolant change, an airlock has remained in the cooling circuit. That should have been prevented, but it will usually dissipate after a few days driving. The overflow tank can then be topped up.
If your coolant has just disappeared while the car was unused, something like a hose must have failed spontaneously, or perhaps the heater matrix has rusted. Improbable, but just possible I suppose.
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One possibility is that after a complete coolant change, an airlock has remained in the cooling circuit. That should have been prevented, but it will usually dissipate after a few days driving. The overflow tank can then be topped up.
I dunno about the Fiesta, but on the Skywing I've found it impossible, with a conventional drain and fill without using special vacuum filling devices, to get all the air out of the system.
Left in it takes quite a lot of driving to burp out, and does a pretty good impersonation of a blown head gasket while its doing so, blowing coolant out of the overflow tank.
The best fix I've found is to idle the engine with a funnel in the radiator, and the cooling fan disabled, so the coolant boils, displacing the air.
I havn't seen this procedure recommended anywhere and it is a bit alarming, but it seems less potentially damaging than normal operation with an air pocket in the cylinder head.
Edited by edlithgow on 01/09/2020 at 04:55
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Thanks for further insights. I'll keep an eye on the coolant level.
In the meantime, I've come across by chance products which claim to seal potential leaks such as Holts Sealit Leak Repair and Holts Radweld Plus Coolant Leak repair.
Are these worth considering - has anyone had any experience with these?
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IIRC there are cheap tablets that incorporate ginger root fibres and are actually GM approved, which are said to sometimes work.
Can't remember the name offhand, but someone will.
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There are plenty of leak sealer products on the market that do work . However, I would only use this type of product as an emergency last resort . You could end up blocking the heater matrix as a result.
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There are plenty of leak sealer products on the market that do work . However, I would only use this type of product as an emergency last resort . You could end up blocking the heater matrix as a result.
When running test cars fully instrumented during development of temperature fan drives, we had to use a BarsLeaks tablet to stop a minor radiator leak.
It stopped the leak but we saw from the extra thermocouples installed that cylinder head temperatures ran about 10 C higher.
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As an update, I took the car out for a drive of around 8 miles.
There were no visible leaks underneath the car when I had a look, but after the car was parked up for around half an hour, I took at look at the expansion/top up tank. About half a litre has disappeared (from what it was before I took it out for a spin).
So I topped it back up and drove back. I immediately check after the return trip and I don't think it has lost any coolant - if any.
Any ideas what might be the issue?
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Head gasket? Get a garage to do a 'sniff' test.
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There are plenty of leak sealer products on the market that do work . However, I would only use this type of product as an emergency last resort . You could end up blocking the heater matrix as a result.
Yup - been there done that! I lost heating after using such a product on my Austin Allegro 1750 SS way back when - never again.
Check for discolouration around the radiator. Modern ones are a pain and can fail at the edges where the plastic sides join with the metal cooling vanes. Not being used during lockdown may have accelerated this issue.
Also - any wet carpets?
Edited by Big John on 02/09/2020 at 23:14
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