Hi All, 
 
So I recently replaced my coolant sensors and in the process of doing so have introduced air into my system. Now no matter what I do I cannot bleed the system. My thermostat is new and I have an aftermarket radiator with a drain bung not a tap:

 
I have tried taking the bung out and putting a 19mm hose over the entire barb that's welded onto it to raise the level and then quickly removing the hose and screwing the plug back in while coolant is gushing out and simultaneously topping up a funnel I have at the rear fill point and still the car is overheating. I have tried squeezing all the rubber hoses and there was some air in the ones to the front rad but seems to be getting better? The end rad tanks aren't really getting hot enough to engage the front fans because of a likely air bubble and all the guides online where I leave it with the hoses all connected to heater and rad bleed valves have not worked. 
 
I've tried turning the engine on with all the bleed valves open, it'll just lower the heater coolant level in its hose but won't run dry and every now and then a small bubble emerges at the back. I've been at this for 3 days now and was wondering if anyone on here has a revolutionary idea about bleeding the car that I may not have tried. I've read the PDF guide here and sadly it's not helping. 

One person has suggested draining the entire system, putting negative pressure and then having it suck all 13L back in but that is an unattractive option right now. The last time I bled the coolant successfully with my set up I just drove around the block, pulled in, waited for it to cool, topped it up and then repeated but now I'm finding that even after I do that I can't top it up with anymore coolant.  

Hey Matt - have you got the rear of the car in the air? When i bleed mine, I put the rear of the car as high as possible and hang the hose from the radiator and heater core on the top of the bonnet. Works a charm.

Maybe chuck a mittyvac on the system overnight to check for any leaks

Hope this helps

You need to bleed the outlet that connect to your heater it's above your spare tyre area. Air gets trap in there. Attach a hose and hook it to the bonnet. And continue doing what your doing with your bleed, Jacking helps. Use a fill free funnel it's the best investment, top it 1/4 way close bleed points, then run motor until thermostat releases a few times keep an eye it, make sure it's got enough coolant in the funnel, as it heats up the coolant might rise. Then let it cool down. plug the funnel, then seal your system. This will work.
 
https://www.youtube.com/watch?v=BQk9HpuIrmA

I can't recommend the Spill free funnel enough. I have the Lisle funnel - can't remember product code at the moment but can check when I'm home. Ordered from Amazon. Definitely worth adding to your tool collection.
 
Edit:
 
Lisle Spill-Free Funnel 24680

As the others have said above, all good advice. Spill free funnel is a must, you can make a temporary one by inverting a 2L drink bottle, seal the neck to your fill point with plenty of blue tack and cut the bottom off so you can pour in coolant. Jacking car a little higher on the passenger side is even better too to help the bubbles find their way to the high fill point.
 
There are 4 hoses to squeeze - 2 near at lowest point towards radiator, hose that attached to thermostat and hose from coolant tree to radiator.
 
You really need a fitting instead of the bung on the radiator so you attach a hose to it, you wont bleed it properly if you cant fit a hose to a level above the highest point. Remove the bung and bring it to a speed shop that supplies AN fittings so they can identify the type of thread. You can probably get one that has a male on one end to fit the radiator with a 90 degree bend and a barbed end on the other. PM for details on a set up for this, I'll send you a photo.

Thanks guys, 
 
I have been bleeding the heater points. I have a funnel that is almost spill free as it fits snugly into the coolant neck:

 
The car is currently sitting like this. The 19mm hose fits snugly over the barb but its not a perfect system as I have to have a 2nd person top up the coolant as I remove the hose in a panic and replace the bung with coolant going everywhere. When I squeeze the hoses that go to the radiator I can hear sloshing which would indicate air in the system which is utterly depressing after doing this for a week. 
 



 
I'll leave it sitting up overnight with the funnel in but as I live in a questionable unit complex I won't leave frunk open. I'll try again tomorrow but this just doesn't seem to be working no matter what I try.

Silly question Is the car running when you are doing the above ?

Yep done both running and not running

stuka
There are 4 hoses to squeeze - 2 near at lowest point towards radiator, hose that attached to thermostat and hose from coolant tree to radiator.
 
You really need a fitting instead of the bung on the radiator so you attach a hose to it, you wont bleed it properly if you cant fit a hose to a level above the highest point. Remove the bung and bring it to a speed shop that supplies AN fittings so they can identify the type of thread. You can probably get one that has a male on one end to fit the radiator with a 90 degree bend and a barbed end on the other. PM for details on a set up for this, I'll send you a photo.

I believe that is good advice, and should work.
You could also incorporate a small tap to the fitting, just like OEM.
Somewhere like Bursons or Repco should have all you need.
 
FWIW:
When squeezing the hoses in an attempt to get all the air out, on my car I have found the most effective squeeze point is the inlet hose going into the thermostat housing in the engine bay. That seems to cause the most bubbles to come out of the bleed hose from the top of the radiator. And that still occurs even after the system has been fully bled according to the service manual.
 
Of course my car is an NA and still has the stock radiator.

Yea I might look into the fittings today. I think I'm going to replace the thermostat again. It doesn't make sense why the radiator is dead cold and the rest of the engine very hot, even the heater hoses up to its bleed point is the same temp as the hoses in the rear. I've squeezed every imaginable hose on the car. 

Last time I bled this system I could drive around the block and top up the coolant a little each time and that eventually bled the system, this time after every short drive its at the top of the neck so I'm thinking the thermostat isn't operating correctly and not opening to allow coolant to circulate to radiator.