98 w900 bunk heatercore leaking

I’d just replace the valve

you could bypass it as a temporary get home fix
But then you’re gonna have hot water running through it all the time .

 

Not if you don't mine 180°f air coming out of the bunk vents when the blower is on back there..

 

You can definitely bypass it. Don’t really need it. You’ll just have to open the hood and turn the valves on manually for heat, and off in summertime, or the air won’t blow cold, it will get cancelled out by the heater core. Assuming you have shutoff valves, on the engine, should be 2 for each heater core. If not, best to have them installed. Good for isolating a leaking core, valve, or hose till you can fix it, without losing all your coolant. Often a heater valve goes bad, and won’t close. A/C doesn’t work well. Just close valves in summertime. It’s a good practice anyway. A small amount of leaking past the valve can cause A/C to not work as well. I’ve seen this happen on brand new Trucks. A/C blows hot, till water valves are turned off. The valve at the heater is a convenience that’s often problematic.