So i noticed the water in the expansion bottle rising kinda high and releasing itself from the pressure cap untill the fan kicks in and then it sucks the water back down to below the max line in the bottle , also noticed a small leak from behind the water union just under the coil pack , is this likley to be the water union itself leaking ? or something else hidden behind there , with out remving everything its a bit awkwards to see where its coming from .Any body had the same or simular issue's ? if so what was the remedy ? or should i replace the water union as good measure and take it from there ? Also wondering if this leak could be the possible cause of the water issue, like sucking in air or something ?


Thanx in advance for your reply's

 

What's the temperature gauge reading when it does it? If the fan kicks in and stops it, it has to be temperature related. A leak could cause air to be drawn in which releaves the pressure so your coolant boiling point has dropped. Sort the leak out and see if it's still doing it. Hope this helps.

 

The thermostat housing is just below the coilpack, these are made of plastic which does often break causing leaks.
The water cooling system does NOT suck in any water, as it can't it's under pressure, so any leak is always outward.
A leak does lower the pressure inside the system though and these can and do run over 100C, so it needs this pressure to raise the boiling point of the coolant.
Where are you filling up to ?, they only need to be on the minimum, but some settle at UNDER the minimum, like my old one(now my dads) 60K on it's new engine coolant settles about 1 1/2" BELOW the minimum, but doesn't use a drop, I merely marked the level where it settled and it stays there constantly when checked.
The cooling system is doing what it should, water expands when it gets hot as do most liquids, hence the tank being a expansion tank, with the fans coming on the water cools and effectively shrinks dropping the level.
Just fix the leak is all that's needed.
tabetha

 

Hi.. How do I fix the leak though. Thanks Jon