So I'm pretty sure we have a manifold coolant leak on our 2012. Haven't been able to determine yet if it's the manifold itself or if it's the bypass tube underneath the manifold. Is this "normal" on a Expy with 148K miles on it? Anyone have any experience doing this work to ascertain the number of hours and $$$ this will take? My thoughts were to replace the manifold, radiator hoses (they're original), thermostat, all gaskets and the coolant bypass tube since I'll have to remove the manifold to do any of the work. I also thought about doing the plugs while I'm at it. Thoughts, tips or suggestions are welcome. Thanks!