Note: On 1996 and earlier XJ, when you remove the spider of hoses and pneumatically operated heater valve, you have full time coolant flowing through the heater core.
Even if the heater core fails.
Looking into blocking off the hoses, or replacing the original stuff to turn off the flow.

 

The original valve still let a little flow through, so I don't think it would stop a small heater core leak.

 

Like Lawson says, the heater valve doesn't completely shut off flow to the core, just diverts most of it.

Are you wanting to shut off all the flow? Is your core leaking?

You can simply connect the 2 hoses before the valve together (loopback). You'll need an adapter since they are 2 different sizes.

I've seen where folks have plumbed a shut off valve (one of the 1/4 turn ball valves) into each hose.

 

As I've eliminated the valve, I am probably going to bypass.

 

Not a good idea to bypass. The coolant in the heater core is then stagnant and tends to corrode and clog.

Are you worried about when your heater core may fail?

 

It already failed, that is why I am bypassing it until I can replace it.

 

Oh, okay. Just disconnect the hoses and plug them together with a fitting.

 

you can also fit a manually operated hardware store tap, that way the flow is shut off, but you can turn it on temporarily if needed when its cold