Poorly-flushing toilet; air bubbles

The toilet on the top floor of the house is often prevented from flushing partly, or wholly, by air bubbles that rise from the drain in the bottom of the bowl pretty instantly upon being flushed. I've read this can stem from blocked jet holes, but cleaning them with a small nail and then pipe cleaners, all around the inner rim of bowl, has not stopped the vigorous bubbles from coming up the drain hole, or solved the problem. (I also have cleaned the large jet passage at the bottom.) Sometimes the bubble is more like one large bubble, and sometimes, many small ones. Sometimes, it just flushes like a champ for no apparent reason.

Any thoughts on what might be causing this problem or what I could do to try to narrow it down?

 

Not my area of expertise but it kind of sounds like a vent issue.

 

Ha, that's interesting, I thought it would be a good idea to clean out the vent when the weather gets warmer, there's some needle-drop over it. That would be great if that's it.

 

Get a bucket with about 1 1/2 gallon of water. Quickly pour the water into the center of the toilet bowl. If it flushes good and strong then there is a problem with the toilet and the drain line and vent are probably good. If you get the same slow flush and bubbling with the bucket test then a clogged vent or drain line is a possibility.

 

I agree... Sounds like it isn't venting properly. Check for obstructions in the vent pipes.