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Discussion Starter · #1 ·
Hey guys. My expansion bottle stays below low. When you fill this up to max this returns to low within a day. The vehicle has done this for about a year and seems to be fine temperature wise. Any ideas why this may be. Would assume doing over 100 miles in the summer over 28 degree would mean this is alright just strange how everyone elses seems to be a lot higher all the time. The level sits halfway below minimum and the bottle fully empty
 

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Discussion Starter · #2 ·
After a long drive this reads minimum due to expansion but while sitting wnter or summer always reads halfway from being fully empty
 

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Pardon the inference, no 'sucking egg instructions' intended here... but you are checking the level and refilling when the engine is stone cold, right?

Just like tyres the readings/levels change dramatically once they've been used.
 

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Potential leak, or airlock, have you allowed the air within the system past the thermostat to be bled? Have you ever bled the fiesta using the suggested points.

for clarity your level you quote are
Maximum
Minimum
Half way to empty
Empty meaning base of tank?
 

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Discussion Starter · #6 ·
Hey man. The system was fully bled yes using the normal method. Yeh halfway to empty meaning below minimum and the bottom of the expansion tank. A little bit from being fully empty
 

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Discussion Starter · #7 ·
The temperature of the vehicle reached 100 degrees and the heaters were on the hottest setting at a medium speed when bleed system with expansion tank bottle open
 

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The temperature of the vehicle reached 100 degrees and the heaters were on the hottest setting at a medium speed when bleed system with expansion tank bottle open
But did you bleed the specific points on the radiator? Air once trapped at a high point is likely never to become untrapped
 

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Discussion Starter · #9 ·
But did you bleed the specific points on the radiator? Air once trapped at a high point is likely never to become untrapped
Not sure what you mean by the specific points bud. Thought you only had to do the expansion bottle opened. Please explain thankyou
 

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Not sure what you mean by the specific points bud. Thought you only had to do the expansion bottle opened. Please explain thankyou
The expansion tank is the highest point, however there other high points, one in the radiator air has to be expelled directly from this high point, air won’t travel back down into the coolant to the open point. I suspect air is present, and being compressed when warm / under pressure reducing the level in the expansion tank. How many times have you topped up, if it’s multiple times you may be burning coolant / or have a small leak
 

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Discussion Starter · #11 ·
Hey yeh this was done from the highest point being the expansion tank. Dont really understand where else to bleed this from. Probably filled this about 5 times in 14 months. Went through the whole summer though and the level remain below low with no problems at all
 

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Discussion Starter · #12 ·
Whenever this gets filled it emptys within a day. Seems to be alright normal temp in 28 degree weather so strange. Thank you for your reply
 

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Whenever this gets filled it emptys within a day. Seems to be alright normal temp in 28 degree weather so strange. Thank you for your reply
I wouldn’t expect it to fault as the cooling is designed for full bhp all time and at maybe 35 degrees, so I expect you will be fine.

because the hoses don’t enter the rad at the very top, then enter near the top, any air in that section won’t be released, similar to why you bleed every radiator in a house not just the top floor rads

however if you’ve filled up multiple times you have a leak. Perhaps the expansion bottle itself. Often these are 2 parts and the join can crack, I suspect this could be another thing to check. Thus why it drops to the same point.
 

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To clarify it is actually full of coolant and not just water? Coolant with increase the boiling point so it shouldn’t steam the same is true for the expansion cap, it should pressurise the system thus increasing the boiling point of the liquid (as well as compressing any air) I think it’s around 1.1bar typically it should pressurise to. Replace the cap see what occurs
 
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