When you bipass the heater core do you connect tubes together or you just shut them completly?

 

I don't think that it matters. The temperature control valve just about completely shuts off the flow, so I guess that you can go either way.

 

I thought about it a lot and come up with solution of my own:
You have to connect them together (In and Out tubes) becouse your heater core is always is ON.
Its maybe wrong or have many other solutions but still its my thoughts.

 

Yeah you connect them together.

Usually what i do is cut right near the connect on the heater core and just run it straight up to where the in tube connects to the block. Of course I usually by pass a heater core when something breaks in the middle of nowhere and I need to limp to a city.

WHy don't you buy a new heater core? THey are relatively cheap

 

It is much easier and cheaper to run a section of hose "IN" to "OUT" than to try and find the right sized reinforced plugs to cap the ends. The heater core is not always on. The control valve practically shuts off the flow, at least on my 91 100Q. So plugging or bypassing is not going to affect the engine cooling.

The heater core is cheap but changing it is a major b-i-t-c-h!

 

Offramp,

You gotta remember that even though you shut off the "in" valve, the "out" hose also has pressure in it.

If the heater core is leaking, you will leak just as much with the valve shut.

Probably too late, but I would strongly advise the OP to change the blower motor at the same time. Hate to have to go through the whole PITA again.

Cheers,

George

 

That is why I said it just about shuts off the flow. It is not like a plumbing valve, there is always some seepage or more like a trickle. The valve is for blocking flow and not holding pressure.

 

I'm changing heater core right now, bought on-line for $62 with overnight shipping. On my car the heater core is always ON.
Replacing it is pain in the ***. So little to unscrew, so much to dissasemble. But its very interesting. This is the first car in my life that has heater on always. The design is very interesting. The heater it self didn't leak but the uper cap did. I think I found the problem in this cars.
The heater core is not secure from the bottom, it is hanging in there, I think if to support it from bottom it will work way longer that 10 years.

 

hi everyone. could anyone point me to detailed manual with pictures on how to replace heater core (b3/b4)?

 

Year and model?