Hi guys,

i have a 2005 cooper that has some overheating problems. it started when the temperature gauge was going up because there wasnt much coolant in it. It went into the garage got seen over and the system was bled and coolant topped up. Now since then when i start the car there is a gurgling sound and i have to rev the engine to flush some air (i think) out of it and and then there is a water noise coming from the passenger side dash, the noise also happens during driving when i stop and the accelerate again.

When i turn the ignition off after driving bubbles are coming from the thermostat and i can see them in the expansion tank. The coolant levels can be inconstant as well one time it all got sucked into the engine so expansion tank was nearly empty then when i drive it comes back over maximum.

When it went into the garage the thermostat and fan was replaced they couldnt find any other problems, i keep thinking it is an airlock but bleeding the system doesnt seem to sort it.

Has anyone had similar problems to this? the garage want to strip the engine and have a look but that is pricey. The air is getting into my coolant system i just dont know from where. A gasket test has come back negative and also has had pressure tests and is negative aswell with no leaks.

Any help would be great.

Thanks :)

If you are loosing coolant it keeps allowing air into the system as the level drops, common slight leak points are distorted thermostat housing + gasket and lower corners of radiator (both have been modified on new parts), not always easy to spot or revealed by a pressure test. Try placing some cardboard on the ground under the engine when parked overnight to spot any drips.

More ideas here which may help:
Solving MINI Cooling Problems.......... - Forums (http://forum.minicooper.org/showthread.php?t=13263)