KnowNothing66 Posted January 9, 2021 Share Posted January 9, 2021 I have just noticed a noise coming from under the bonnet of my Fiesta 2016 Ecoboost 1 litre and found the expansion tank was bubbling. I have googled a few things and saw 'Damaged Head Gasket' at the top of the list, but I feel sure a car with around 20,000 miles may not have this. My suspicion is that I had to replace the expansion tank cap with one from eBay after the original cap separated from its threaded part a few weeks ago and it was a bugger to get out.I feel I may have damaged the thread on the expansion tank and its slightly mis-shaped and the new cap may not be screwed on as well as it should even though there is no movement from it and no coolant seems to be escaping. Is it probable a whole new expansion tank is needed or could it be something else? Thank you in advance for any replies. Quote Link to comment Share on other sites More sharing options...
Neb_engineer Posted January 9, 2021 Share Posted January 9, 2021 Just to rule out head gasket, can you check there is no oil in coolant/ coolant in oil Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 9, 2021 Author Share Posted January 9, 2021 Just now, Neb_engineer said: Just to rule out head gasket, can you check there is no oil in coolant/ coolant in oil I will have a look in the morning.Will it be very noticeable? I only ask as my coolant is bright orange so I'd expect a significant colour change if so. Quote Link to comment Share on other sites More sharing options...
Neb_engineer Posted January 9, 2021 Share Posted January 9, 2021 You might be able to see oil floating at the top of the expansion tank, also on the dipstick the oil will either look milky or be more full than expected or have a line of coolant above the oil or a mixture of those things 1 Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 9, 2021 Author Share Posted January 9, 2021 Cheers.I will get back to you and thanks for the advice. 1 Quote Link to comment Share on other sites More sharing options...
anon Posted January 9, 2021 Share Posted January 9, 2021 If the cap is not secure, the engine WILL boil. 1 Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 9, 2021 Author Share Posted January 9, 2021 Just now, anon said: If the cap is not secure, the engine WILL boil. There doesn't appear to be any leakage at the moment,nor does the cap seem loose but I will obviously check that too. 1 Quote Link to comment Share on other sites More sharing options...
anon Posted January 9, 2021 Share Posted January 9, 2021 You are not losing coolant. The engine normally runs at 90 and the pressure cap stops it boiling until 112 or so. If there is no pressure cap, the radiator could be pulling the temperature down to 90 but it may be coming out of the engine well over 100, causing the boiling. You will not be losing much coolant but there should be the odd wisp of steam when it bubbles if the seal has failed for any reason. What does the temperature gauge read? With a cloth over your hand and preferably a thick leather glove to prevent scalding, you could gently release(NOT REMOVE) the pressure cap. if it gets worse, you have another problem but if not, that will be the cause. Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 9, 2021 Author Share Posted January 9, 2021 13 minutes ago, anon said: You are not losing coolant. The engine normally runs at 90 and the pressure cap stops it boiling until 112 or so. If there is no pressure cap, the radiator could be pulling the temperature down to 90 but it may be coming out of the engine well over 100, causing the boiling. You will not be losing much coolant but there should be the odd wisp of steam when it bubbles if the seal has failed for any reason. What does the temperature gauge read? With a cloth over your hand and preferably a thick leather glove to prevent scalding, you could gently release(NOT REMOVE) the pressure cap. if it gets worse, you have another problem but if not, that will be the cause. Temperature reading seems fine,within normal limits when I was driving. Quote Link to comment Share on other sites More sharing options...
tomshepp Posted January 10, 2021 Share Posted January 10, 2021 The key things are that you are not losing coolant and the temperature is normal. The big expensive problems can be dismissed. At worst you need an expansion tank if the filler cap thread has been damaged. Carry out the test that was suggested and examine the seal in the cap to ensure that it does in fact screw down fully. If it does not, buy a genuine cap if the thread is undamaged. Quote Link to comment Share on other sites More sharing options...
iantt Posted January 10, 2021 Share Posted January 10, 2021 You sure it's not the auxiliary electric coolant pump running when engine is switched off. It keeps the coolant flowing around the turbo for a few mins. This coolant then flows back into the expansion tank. 3 Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 10, 2021 Author Share Posted January 10, 2021 5 hours ago, iantt said: You sure it's not the auxiliary electric coolant pump running when engine is switched off. It keeps the coolant flowing around the turbo for a few mins. This coolant then flows back into the expansion tank. Excellent point.I've never noticed this before and having checked problems mentioned such as oil in coolant(no) problems with sludge or residue in oil (no) and cap loose (again no) then maybe it is simply this?? I'd never heard or soon a car doing this previously so maybe I panicked a bit for no reason? Quote Link to comment Share on other sites More sharing options...
iantt Posted January 10, 2021 Share Posted January 10, 2021 Next time you check, just look at the small pipe that enters the tank at the top and see if it's flowing through at that point. Obviously the engine needs to be warm for it to activate the pump. 1 Quote Link to comment Share on other sites More sharing options...
Robhonda Posted January 10, 2021 Share Posted January 10, 2021 On 1/9/2021 at 3:36 PM, KnowNothing66 said: I have just noticed a noise coming from under the bonnet of my Fiesta 2016 Ecoboost 1 litre and found the expansion tank was bubbling. I have googled a few things and saw 'Damaged Head Gasket' at the top of the list, but I feel sure a car with around 20,000 miles may not have this. My suspicion is that I had to replace the expansion tank cap with one from ebay after the original cap separated from its threaded part a few weeks ago and it was a bugger to get out.I feel I may have damaged the thread on the expansion tank and its slightly mis-shaped and the new cap may not be screwed on as well as it should even though there is no movement from it and no coolant seems to be escaping. Is it probable a whole new expansion tank is needed or could it be something else? Thank you in advance for any replies. There is a test that can be done to rule out head gasket leaking into the water system, It’s an attachment you put on the top of the header tank , it contains a fluid that changes colour if it detects exhaust fumes . 2 Quote Link to comment Share on other sites More sharing options...
KnowNothing66 Posted January 10, 2021 Author Share Posted January 10, 2021 15 minutes ago, Robhonda said: There is a test that can be done to rule out head gasket leaking into the water system, It’s an attachment you put on the top of the header tank , it contains a fluid that changes colour if it detects exhaust fumes . Any idea where you can get hold of such a device? Quote Link to comment Share on other sites More sharing options...
Robhonda Posted January 10, 2021 Share Posted January 10, 2021 8 minutes ago, KnowNothing66 said: Any idea where you can get hold of such a device? There are a number of kits out there some a cheap as £6 it’s called a combustion head gasket tester kit. Some of them are more expensive because they actually fit the different threaded header tanks , some of the cheapest ones have like a funnel neck you just push over the filler neck 1 Quote Link to comment Share on other sites More sharing options...
Robhonda Posted January 10, 2021 Share Posted January 10, 2021 Just now, Robhonda said: There are a number of kits out there some a cheap as £6 it’s called a combustion head gasket tester kit. Some of them are more expensive because they actually fit the different threaded header tanks , some of the cheapest ones have like a funnel neck you just push over the filler neck Most motor spares places will stock them , if not there are lots of them advertised on line Quote Link to comment Share on other sites More sharing options...
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