Check valves can go bad, however I can't imagine where you'd have a check valve in a normal hot water system.
Check the compression of the cylinders you will have a low reading in the one with a bad valve
I think that is what caused my water lines to have too much air in the water
To check for a leak, apply soapy water to the stem and look for bubbles.
Obstruction in the hot water supply line, bad valve, or broken water line. Drain system and remove valve cartridge, open hot supply to blow out line and see if water comes out. If it does than you have a bad cartridge, if not broken line that needs to be repaired.
You pop the seal and see if it closes properly. If there is any doubt at all, it's easy to change. - If you are operating a jet pump and it won't prime, the foot valve ( just a different check valve ) is always suspect.
You either have a vaccuum leak, or the check valve for the ac system has gone bad. The check valve is on the passenger side. It is the black part in the vaccuum line that runs along side the ac lines at the firewall.
Check the PCV valve and system for proper operation. Do a wet and dry compression check to determine if you have bad rings.
Check engine lit goes on.
It can.
If the leak is bad enough i believe it can but i would check your valve cover gasket first.
Yes, but it could also be may other things. Check your OBDII system error codes.
Yes it can if it is bad you will see the cel