Hello everyone,

I am going to bypass my heater core since it is leaking. At this moment I do not have the time or money to fix it so I had a quick question about flushing the coolant with a bypass.
After flushing the system with distilled water and topping the tank off with G12 coolant, how do I bleed the system with the heater core bypass? I have heard some people lifting the coolant tank as much as possible and then filling it up till it coolant comes out of the bleeder hole but others say that you have turn your heater on high heat.
I thought that you need the thermostat to open in the first place in order for the coolant to flow to the heater core so would that work if your engine is not warm?
I have a 2001 Audi A4 1.8T

 

I think that would depend on exactly how you bypassed the heater core. The bleed port should be the highest point in the plumbing, because that's where the air will collect. Normally that's your heater core. Depending on how you plumbed the bypass, I'd guess your expansion tank is now the highest point. Personally I've never used the bleeder port on the heater core, I just ran the car up to temp with the cap off the expansion tank and it worked fine.

 

I've never even had to do that, I just slightly overfill the expansion tank, drive for a day or two and then top it up whenever it's needed. This isn't a BMW where you have to bleed it for hours and go through a litre of coolant just to get the air out.

 

yeah i've never had to bleed mine out either. but if you do need to bleed it, why not make your own bleeder? splice the two heater hoses together with a special union with a hole in it and bleed to your heart's content

 

Thanks for you input guys. The reason why I ask is because I'm going to replace the coolant expansion tank and obviosuly the coolant and the coolant temp sensor. I have a leaking heater core and I do not have the money nor the time/place to fix it so I'm goin to bypass it for now. I have read that air pockets might make your engine overheat and that's why I want to bleed the system.

 

If you get air pockets, it will over heat even at idle, depending on where they get stuck. I would drain all the coolant, replace the tank and temp sensor, fill everything back up and then run the car up to temp in your garage with the cap off the new tank. That should do it!

 

How permanent is this bypass going to be? If it were me, I would get some copper pipe the same diameter as the heater core pipes on the firewall and 2 90 degree fittings. Solder those together in a "U" shape to go from one heater hose to the other. In one of the two pipes where it slips into the hose, drill a bleeder hole, just like the stock setup.