Mk2 Golf - coolant system drawing in air

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Sat 30 Jul 2011 15:05
Mk2 Golf - coolant system drawing in air - golf-driver

I have a Mk2 Golf with a 1300 engine. My coolant system is drawing in air.

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When I have driven for more than 20 miles the coolant level in the expansion tank will drop.

After waiting 1 hour until the engine has cooled I gently open the expansion tank cap and let out the built up air, the coolant level then increases back to it's original position.

If I wait 12 hours before opening the expansion tank cap the coolant level does not increase and it stays at it's lower level. I notice mild coolant leaks from one side of the radiator wall and from 2 coolant hose junctions.

Basically then my coolant system is drawing in air, if I do not bleed this air off the built up pressurised air in the expansion tank pushes coolant out of the minor coolant system holes.

Where could the air be drawn in, how do I stop this?

Whilst driving the coolant temperature is normal. I am temporally using just water as coolant.

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Sat 30 Jul 2011 17:05
Mk2 Golf - coolant system drawing in air - acornarms

hi you are not drawing in air ,but the system is building up pressure as a part of cooling repaire the leaks and you will stop loosing coolant

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Sat 30 Jul 2011 17:14
Mk2 Golf - coolant system drawing in air - Peter D

Suspect leaking head gasket over pressurising the coolant system. Regards Peter

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Sun 31 Jul 2011 16:52
Mk2 Golf - coolant system drawing in air - golf-driver

There is no oil in the coolant water and no mayo under the oil cap.

The expansion tank cap seems ok, it is a tight fight.

If I bleed off the expansion tank air at the end of each journey there is no coolant leak.

With the engine running and stationary everything is normal (just a bit of steam from the radiator).

Is it possible that whilst driving air is drawn into radiator minor holes and this goes from the radiator to the expansion tank via the hose. Is this what the radiator to the expansion tank hose is for?

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Sun 31 Jul 2011 17:31
Mk2 Golf - coolant system drawing in air - Peter D

"Steam from the radiator" Clearly the rad is leaking. If it is then when the engine cools right down it can draw air in through the pin hole leak faster than water was leaking out thus influencing the header tank level. Regards Peter

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Sun 31 Jul 2011 17:53
Mk2 Golf - coolant system drawing in air - Peter.N.

The pressure in the cooling system rises as the temperature increases, once the temperature stabilises the pressure should remain constant so once enough water has leaked out to compensate for the initial pressure rise you shold have no more leakage unless the engine cools down and is then heated again. So under normal driving conditions if you are continually loosing water the chances are that the head gasket is leaking and pressurising the system.

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Sun 31 Jul 2011 17:54
Mk2 Golf - coolant system drawing in air - galileo

Is it possible that whilst driving air is drawn into radiator minor holes and this goes from the radiator to the expansion tank via the hose. Is this what the radiator to the expansion tank hose is for?

Cooling systems normally run at up to 7 pounds per square inch (0.5 Bar) ABOVE atmospheric pressure when up to temperature, so it is impossible to 'suck' air into the cooling system except, as explained, when steam condenses as it cools down. This can only happen if there are leaks somewhere and coolant has leaked out leaving space for steam.

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Mon 1 Aug 2011 15:07
Mk2 Golf - coolant system drawing in air - golf-driver

I will replace the radiator then.

Is the radiator supposed to move a bit raltive to the vehicle frame? The top brackets just slot into a hole so I assume this allows for movement?

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