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Discussion Starter #1 (Edited by Moderator)
Hi all
I own a 2007 VW Golf 5, 1.9TDI diesel.
Car is very nice to drive and has enough power when needed.

I do have one irritating problem with it. It looses coolant. There is no leaks and pressure test and block test came back positive.
I suspect the water pushes back into the reservoir and escapes via the overflow. This happens even overnight when the car is stationary. When I remove the cap of the reservoir and let it stand like that overnight, no coolant is lost.

Remedies thus far:
Flushed system (done by mechanic so does not know if it was done properly)
Replaced thermostat.
Replaced cap of resevoir.

Found some info about the EGR (Exhaust Gas Recirculation) on the web and it looks like this is where the problem is. I have no idea where the EGR valve is or what can be done about is.

Mechanical experts are dumbfounded on this one. Dealers want to replace radiator, waterpump and what else ($$$$$$$). I just do not have the money to fund someone's experiments.
 

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EGR valve is not the problem but there is a EGR cooler next to it that has coolant going through it to cool the EGR exhaust. read the EGR FAQ article in the FAQ. However, if it passed a pressure test, it should not be leaking. If the reservoir cap also passed the test and is new, it should not be leaking there.

There must be a leak somewhere in the engine or it's burning coolant or it's leaking out the reservoir. If this much work has been done to it, I suspect they have not seen any leaks on the outside of the engine?

also, since this is a tech post, moving to mk5 section.
 

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Discussion Starter #4
Coolant loss

Looses between 300ml and 600ml.
What I do is when the car parks for overnight, I open the reservoir cap and let it stand like that. No coolant is then lost. My wife drive the car for a couple of days and no coolant is lost.
Seems like there is a pressure building up and pushing it out via the overflow of the reservoir.
I am scared to take the car on a long trip.
 

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Looses between 300ml and 600ml.
What I do is when the car parks for overnight, I open the reservoir cap and let it stand like that. No coolant is then lost. My wife drive the car for a couple of days and no coolant is lost.
Seems like there is a pressure building up and pushing it out via the overflow of the reservoir.
I am scared to take the car on a long trip.
It could be the vent valve in the cap. Try replacing the cap. If pressure builds up, it might damage parts of the cooling system.
 

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Discussion Starter #6
So replaced the EGR cooler (just over ZAR 5K). Low and behold there is still a puddle of water under the car. Car stood for a day and a half and coolant is under the minimum. Had to put in more and took a short drive. Got back and released the pressure by opening the reservoir cap. Checked this morning and no water under car.Wife will drive with car to shops during day, so I will check tonight.
 

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Discussion Starter #7
It could be the vent valve in the cap. Try replacing the cap. If pressure builds up, it might damage parts of the cooling system.
The cap is rock solid, I do not see any vent. This cap was bought from the dealers.
 

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On my Jetta the waterpump shaft seal leaked, but could find the leak until the first timing belt. was changed.
 

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Discussion Starter #9
Will let car stand overnight at mecchie. With cover removed, any leak should hopefully be visible.
 

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Zdravým stal som sa vlastníkom automobilu golf 5 2004 1.9 77KW a typ motora je BKC.
možné spoľahlivosťou na motoroch sú časté závady?
 

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Zdravým stal som sa vlastníkom automobilu golf 5 2004 1.9 77KW a typ motora je BKC.
možné spoľahlivosťou na motoroch sú časté závady?
First posts normally go in introductions else you could get a free fix and we never see you again!!!

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