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Engine coolant level weirdness!


Dickie-D
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Are the weird symptoms below indicative of air still working its way out of the system or is it more likely to be a faulty water pump/thermostat housing?

 

The car is a March 2018 model. I bought it used in August 2020 with 14,700 miles on it. The first coolant level warning message appeared in February 2022 at 21,000 miles. I've topped-up with ready mixed G12evo engine coolant three times and the total volume added throughout this year is 1 litre.

 

After a red warning message on 18 Aug (with no prior yellow warning) I checked the coolant level while parked on a relatively level driveway, after allowing the  engine to cool. It was 20 mm below the minimum mark, despite being topped-up a month ago. I refilled it to halfway between the minimum and maximum marks and drove home (less than 10 minutes of sedate driving).

 

When checked again on my level driveway as soon as I got back, it was 5 mm below the minimum mark, so it had dropped by about 10 mm in that short time. I did not top-up because the engine was still warm.

 

The engine was allowed to cool for 2 hours before checking again and this time the level was only 1 mm below the minimum mark. How can the level in the expansion tank rise by 4 mm when the engine has been allowed to cool for two hours?

 

I topped-up to halfway between the minimum and maximum marks. Several hours later, after checking it was still at the same level, I took the car for a drive at up to 60 mph on some twisty roads with humps. When I got home, the coolant level had dropped to 2 mm below the minimum mark (checked when the engine was still hot). No warning messages had appeared during the drive. There was also a possible smell of 'curried' coolant coming from the engine bay, but I'm not 100% certain about this.

 

The car was left parked overnight and checked again the following afternoon. The coolant level had risen to 3 mm above the minimum mark. In other words, it had risen by 5 mm when the car had been sitting unused for 18 hours.

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Just from the fact you’ve topped up 3 times in ownership including 1 litre this year. I think it’s likely you have a slow leak. Air shouldn’t be still being purged after 4 years 22k miles. With the undertray off and inspection mirror and light source look at the water pump thermostat assessmby. Probably check engine bay b4 that!

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As above it's probably a leak from thermostat/water pump...i am filling mine at around 150ml per 500 miles so waiting for it to get worse before i book it in so it's obvious to the garage.

 

However i have a 1000 mile trip in Scotland starting tomorrow so i will see if that causes it to leak any more than normal.

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Thanks for the responses.

 

I've topped mine up with 289 ml per 500 miles.

 

What confuses me is the level in the expansion tank rising after I switch the engine off. Today I watched it rise by at least 7 mm over a period of just a few minutes. I thought the level would decrease as the liquid and engine cooled.

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Hi, you have added a litre of coolant to a sealed system - its leaking. The (normal) rises and contraction you see are the result of a pressurised system with air in the header tank - totally as it supposed to do - its called an expansion (header) tank.

 

There have been a few with air in the system as a result of incorrect filling at factory (few and far between).

 

I would suggest for a full pressure test - this hopefully will reveal the leak (probs the thermostat / water pump housing). Or just run it and top it up (a litre over a year is a slow leak) it will eventually get worse - at this point the leak should be obvious.

 

cheers D 

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It should be super obvious to the tech's if they look in the engine bay, just by the way the coolant dries. 

 

It's also really common on our cars so they'll know the usual places to look.

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I've just had my water pump replaced today, I simply jacked my car up on stands took the under tray off, coolant was in the tray and you could see the drip when you looked up at the water pump, not a cheep job!!!

Sent from my SM-N976B using Tapatalk

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