I was getting ready to change hoses, and noticed that the heater core was bypassed.. it wasn't something I noticed before, as I have only driven it on warmish days.

I'm sure this was done for a reason, so I'm wondering if there's any point trying to flush/leak test, or just move on to something else, order the core, and replace.

I'm tempted to just leave it bypassed, as it's been running fine as is, but I've also read some threads saying this could be bad for the system..

just curious if there's anyone out there running theirs bypassed and what the risks may be.

 

Engine size?

 

5.3 v12

 

If the bypass takes the coolant straight from the A bank rear water manifold and connects it to the heater core exit pipe that runs down the chassis rail on the LHS (US driver's side) then this is very bad. This is because the bypass takes hot coolant straight from the A bank head and feeds it straight back to the radiator exit and into the water pump, without being cooled in the heater first.

The best thing to do if you do not need the heater connected, is to block off the A bank exit to the heater and to block off the spigot on the radiator exit pipe that the heater return goes into. Just blovking the flexible pipes with a suitably sized bolt dnd jubilee clip will do.

 

 

appears to go straight from heater valve to chassis hose to radiator.

 

If the heater valve is closed, no worries, test it with the car warmed up to see if the hose back to the rad is hot or not. If it is open, close it or block it off somehow.

 

thank you, I will do this for now... ordering new core for future install.

thank you very much, greg.