Author Topic: Coolant top up query  (Read 7470 times)

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Offline Cap

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Coolant top up query
« on: August 22, 2017, 06:12:51 am »
Hi all
Hope someone can help with this. Just bought a 2014 2.2d sport estate. It was due a service so booked it in to main dealers. I mentioned that the coolant was low and they said don't worry all levels will be checked and topped up.
Picked car up fine. Next day thought to check coolant and it was still low where it was before. Took it back to dealer. The service manager asked me to speak to a mechanic who said he serviced the car and the coolant level was fine. He said the plastic tank with the f and l marks was not a header tank and is just an overflow and he had checked level by removing the radiator cap. He advised me to do it this way and if needed top up from the radiator but couldn't show me as I'd just drove to the garage and it was hot. Does this sound right? At present the level is still low in the header / overflow tank. Thanks

Offline apav

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Re: Coolant top up query
« Reply #1 on: August 22, 2017, 08:05:01 am »
That sounds right. If the overflow tank is between full and low, you are fine. If the radiator has a cap, you top up from there.

Offline Cap

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Re: Coolant top up query
« Reply #2 on: August 22, 2017, 01:21:48 pm »
Hi thanks for the response. The level in the overflow tank is below the low indicator. The mazda mechanic had seen this as well. Just thought it was strange as says in the manual to check the level on this overflow tank but he's telling me to check it from the radiator cap.
Thanks

Offline Willpower

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Re: Coolant top up query
« Reply #3 on: August 22, 2017, 02:14:50 pm »
If your radiator has a cap, then it is not a sealed system.  In which case what you are looking at is an overflow tank. You need to check your fluid levels and top up via the radiator cap.  Therefore the fluid level in this container would seem to be indicating low but is in fact fine, because you have no overflow.

If your radiator did NOT have a cap then it would be a sealed system. In which case what you are looking at would be a reservoir. In this case the fluid level would be higher, indicating that there was fluid there to replace any water leaving the system i.e through a leak.  Only if the fluid level subsequently dropped, would that be a warning (and you would probably know about that anyway through other warning signs).
At this point after fixing the problem, you would top up the system via this reservoir.   
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Offline Cap

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Re: Coolant top up query
« Reply #4 on: August 22, 2017, 05:07:25 pm »
Thanks Willpower. Great explanation!

Offline Jerby

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Re: Coolant top up query
« Reply #5 on: August 24, 2017, 07:59:16 pm »
What you are looking at is an expansion reservoir. When the coolant heats up in the radiator and expands it expands into the expansion reservoir. When it cools, the vacuum sucks the coolant back in. If you have a slight leak the coolant in the radiator will be topped up by this reservoir. No need to take the radiator cap off. Simple physics and mechanics.

Offline mareng73

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Re: Coolant top up query
« Reply #6 on: January 10, 2018, 03:27:51 pm »
If the level is below low when cool then perhaps you need to add a little to bring it up to  Low.
If in any doubt have a pressure test done on the system.
I would say most systems are pressurised, the cap should have a spring in it, might be small unlike the older caps.
« Last Edit: January 10, 2018, 03:30:38 pm by mareng73 »
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