I'm going to change my coolant temp sensor tommorow I was advised that if I open the coolant resevoir lid then close it, then pinch a hose (not sure which one?) it sucks the suction back up and stops coolant gushing out ?
mk4 golf 1.6 8v engine code AEH
The big hose. It might or it might not. You'll know when you get near the last thread..
I did have a peek this morning, there is a big hose going to it via a small one.
the trick is to release the cap, put some plastic over the cap hole and replace the cap loosely, squeeze any big hose (which will push fluid back up into the header tank, do up the cap (the plastic will stop air being drawn back in) the fluid level in the tank should stay high if you have done this correctly. Undo the sensor and quickly screw in the new one. Fluid loss will be tiny. Top up if needed. However if the coolant is over two years old it is a good idea to change it anyway.
Wrong sequence, remove lid, squeeze & hold hose, refit lid then release hose. Then change sensor whilst crossing fingers, then top up.
most lids will let air back in (by design)
Peter smith expressed precisely :
Remove the cap, pinch the hose to force as much water out of it as possible, then replace cap - after first placing a plastic bag between the cap and the opening to form a temporary seal, then finally release the hose. The idea is to create a bit of a vacuum in the cooling system, enough to prevent water escaping. The plastic bag is to prevent air getting back in via the caps breather.
When you have finished remove the plastic bag.
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