My bathroom sink traps make a bubbling noise when the stool is flushed, is there a vent problem? How can I check this out and fix?
Thanks

Let's be very clear on this. Do you hear a "bubble" or a "gurgle"? To check, fill the lavatory bowl and flush the toilet at the same time you drain the lavatory. Any bubbles comeout? When your fixtures began to talk back to you they do it in two ways. They "gurgle" atcha or they "bubble" atcha. The "gurgle" is caused by vacuum caused by a blocked vent. The noise you hear is the sound of the air venting through the water of the trap. The "bubble" is caused by back pressure due to a partial blockage What happens is that when you flush or drain the discharge runs down the drain line and hits the partial blockage and bounces back sending a bubble of air ahead of it. A partial blockage will also cause a backup sending soap or crud into a fixture until it can drain away
The two are completely different. Bubbles indicate a clog in the drain line and gurgles indicate a blocked vent. It's important that I know which you have. Back to you, Tom

Tom, it is a gurgle without water in the bowl.

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Originally Posted by sillyfool

Tom, it is a gurgle without water in the bowl

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You have a blocked lavatory vent and the sound you hear is the system attempting to vent through the lavatory trap.
The solution would be to snake the lavatory roof vent. Put out enough snake to reach the base and about 16 feet more. Good luck, Tom