Check the flush valve to see if it is sealing tight.
Check the fill valve to see if it needs to be rebuilt or replaced.
yes i have don it befor
replace the fill valve
You don't, it should com up the pipe joined to tank.
check that the toilet stopper has been switched on and check that the strainer inside the toilet inlet is clear of debris
typically these two problems are caused by two different things. A running toilet is most commonly caused by a leaking flapper (when you push down on the flush handle a chain lifts the flapper and lets the water escape the tank and "flush' into the bowl.) a water spurt is usually caused by a faulty fill valve (the part in the tank that attaches to the water supply and fills the tank after it is flushed.) with an 8 year old toilet both of these parts would most likely be worn out, either thru age or use. T Line
Most likely the flapper in the bottom of the tank is not sealing and letting water seep into the bowel.
Sounds like the flap that allows water to enter the bowl from the tank, isn't sealing. If this is true, the water will be constantly running.
The width of a toilet tank can vary in size. The average width of a toilet tank is about 18 inches.
Inside the tank, usually on the back wall, there will be a number impressed into the porcelain. This is the tank number for a two piece toilet, or a model number for a one piece toilet. It's usually a four digit number, sometimes preceded with a K- (example: K-1234). Sometimes this info is repeated on the underside of the lid. Usually the lid also has a five digit number, which is the lid number. All of these numbers can help you find the replacement parts to repair your toilet.
The water in the lower toilet is probably being siphoned out of the tank by the negative pressure caused by flushing the upper toilet. This CAN happen if the water level in the tank of the lower toilet is over the top of the ballcock. If this is the case, the tank water is being siphoned into your drinking water! Replace the ballcock with a Fluidmaster right away. If you have a small white fill valve that sits in the bottom of the tank, get rid of it. These are illegal and WILL siphon under these conditions. If the lower toilet runs AFTER the fill cycle of the upper toilet, it may be that the ballcock seals at a lower pressure, and the pressure spike when the upper toilet shuts off causes it to run a bit until the added water closes the valve a little tighter.
They are called tank bolts.
Toilet tank