Four years ago I moved into a 1984 built house with its original bathroom (upstairs) and kitchen. I had both replaced about two years ago.
Recently, the kitchen sink has started to gurgle just after being emptied. No problem with the speed the water drains and I have checked the U bend. It also gurgles after the dishwasher and washing machine empty. I have lifted the manhole cover outside - all clear.
Upstairs there is no problem when flushing the loo or emptying the bath. However, the bathroom sink does make one big 'glug' when emptying.
The bloke that fitted both does not know what the problem might be.
Any clues please?