Has anyone experienced problems with these valves.  I am finding that the check valve sticks open and I am getting backflow through the idle pump. 

Don't use multi-purpose valves, they don't do anything well. It's like must cheap stuff, it doesn't work well.
 
Want a check valve, get a check valve.
Want a balancing valve, get a balancing valve.
Want a shut-off valve, get a shut-off valve.

Talking to a lot of engineers, not many of them like MPV's.  Sticking check valves are a common problem, but the major complaint is the dual, balancing shutoff function.  It takes a lot of turns to actually shut the valve, and then you have to rely on the valve being turned back to the same position.  If it's turned to full open, then all that's there is a really expensive shutoff valve, where the check valve MIGHT work.

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