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Coolant Loss

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#1 ali66



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Posted 23 February 2019 - 05:47 PM

Topped oil , coolant etc prior to a 400 mile journey to Glasgow yesterday - driving around today the coolant light came on after only driving half a mile or so - had to top up with 1L of water and then drove 4/5 miles and purchased some radweld plus and added this in - have done a couple of 4-5 mile journeys since and coolant level doesn’t seem to have dropped - due to drive the 400 mile return journey tomorrow but bit concerned about this happening on the motorway - any suggestions or advice appreciated

#2 BrianH


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Posted 26 February 2019 - 08:06 PM

You obviously have a leak somewhere, its just a case of finding it. Given you have put the radweld in already it may have worked for once, but your best bet if it comes back is to take the undertray off, then see if you can see any signs of leaking under there.


Some clue what year/model you've got will help - but given its probabbly either a mk1 or mk2 its likely to be either a corroded radiator, thermostat housing, fan switch holder (as its plastic and can crack) or the heater matrix. You'd be likely to smell the heater matrix and notice it misting the screen up.


Really wouldn't recommend radweld - it rarely works, and is likely to block stuff up.


Your more likely to see the leak when the cooling system is under pressure - either when the engine is hot, or with a pressure tester.

#3 ali66



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Posted 02 March 2019 - 02:00 PM



Car didn't make it back from Scotland! It was losing coolant on the way back so decided to call my breakdown company to get it relayed back home.


Have had the undertray off but no signs of a leak - the coolant loss is definitely coming from the  expansion tank -  this only seems to be the case if driving  - I've had the car idling on the driveway up to running temp but the coolant doesn't escape when just idling.


I've taken the expansion cap off and brought the engine up to operating temp but there doesn't appear to be any bubbles coming into the expansion tan and it doesn't boil over.


I have purchased a new expansion cap today and fitted it but this doesn't stop the problem.



The heating works fine in the front vents but only cool air comes out of the rear vents.



The car is an 02 plate 1.9 TDi Zetec Mk11


If the run on pump has gone would it cause the problem I have ?


Any help appreciated

#4 Amarok


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Posted 05 March 2019 - 05:01 PM

It sounds like you have an Airlock or possible blockage in the system somewhere The rear heater is via the run on pump and as you say its cold so again I suspect its not fireing up the glow plug.

This would be my course of action here

1. Get a new thermostat and fit it

2. Flush out the system

3. Refill and Bleed the system ( I would just use water at this stage) Heater on Hot

4. Take it for a run around the block and get it up to operating temp (80 degrees ??)

5. Drive home and park up and keep the engine running on idle for at least 10 minutes (feel the main pipes in and out of Rad) I gently squeeze them a see the water bubbling in the expansion tank.

check for leaks and that the fans come on to cool the engine

if all is well let it cool down and empty the expansion tank and refill with anti freeze (it should take around a litre of NEAT anti freeze) please note Neat as this will mix with all the fresh water and bring your anti freeze up to the required mix. Same procedure drive around the block or only a couple of miles till warm back home again 10 -15 minutes idle and see if it looses water. The Anti freeze will find the weak spot VERY fast. Its better to fix the leak then use Radweld to fix a leak this stuff blocks up your heater matrix and never really works BARRS Leaks is the only product I have found to stop leaks around Core plugs etc (MOD has BARRS leaks Sticks in the toolkit to fix bullet holes) BUT as I said this should be your LAST resort


Best Wishes