A few months ago we got a Mr. Coffee coffee maker to replace the old coffee maker that had died of old age. it was attractive enough and cost just over $10 so we picked it up. Right from the start this Mr. Coffee CG12 would spit and hiss more than we liked, and as time went by you would have to hit it on the side to make it spit out hot water instead of steam. Otherwise it would just make an annoying gurgling/hissing noise and take for-e-ver to brew a pot. This sucks, especially when three months later you have to smack the coffeemaker every 5 seconds just so your coffee is done inside of 20 minutes. Yesterday, frustrated at having to babysit the percolator, I determined to send it back to the store for an exchange.
Today, I brewed my coffee in a pot on the stove and broke out the screwdrivers. One #1 Philips and a somewhat esoteric security Torx bit are all that are required to completely disassemble the machine. I took the water inlet hose off and blew/sucked. Sure enough, there is a check valve in there and sure enough it was not sealing against pressure from the boiler side. Squeezing gently on the tube is enough to pop the check valve out. The little ball inside the check valve was covered in what looked like sand. Hard water deposits, very likely. I cleaned it off and noticed that the ball is two hemispheres glued together with a little lip around the edges where it was not glued perfectly-round at the factory. I shaved off the casting flash and polished the rough edges with a knife VERY carefully as any gouges would render it useless. I cleaned the seat inside the valve with a Q-tip.
Then I gave the whole machine a good overall cleaning, put it back together, and was back to making coffee. I ran several pots of water and a half-pot of vinegar to get out the loose chunks of chalk, brewed a pot of coffee, and learned a minor lesson:
Don’t let it heat up the water, spitting water back into the reservoir while you add the filter and coffee- this will only speed the otherwise slow death-by-calcium deposits of the check valve.
Review: this was a decent maker, as long as we kept the check valve clean. About a year after we got it, it has been replaced with a new (different) model. The heater failed (open circuit) and the maker wouldn’t heat. Boo.