Hi,

 

I have drained the coolant out of my Mk2 191FSI (V6), and am trying to clean the radiator.  Has anyone done the same?

 

I'm finding that with the heater on, and temp at 90degC, only a limited amount of coolant is drawn into the system (about 5-6L).  Any more stays in the resevoir. 

 

The workshop manual is really vague, but does refer to a N279 valve - and I have seen postings like this https://forum.obdeleven.com/thread/4526/help-turning-n279-shut-valve that describe the valve creating a closed loop at the heater, bypassing the engine circuit.

 

When I use a vacuum pump on the return valve I get the impression it's closed.

 

I have seen suggestions that VW/Skoda systems are self-bleeding.  Is it not that simple?

 

Thanks

I thought the N279 valve was for cars with the aux heater - not normally fitted in the uk. It so the auxiliary heater only has to heat the heater matrix and not the whole cooling system.

 

Not sure about the v6 but on my humble 1.4 all pipes lead up towards the coolant tank including a small pipe from the top of the heater pipes so should be self bleeding. Normally after filling you keep squeezing the rad bottom hose to encourage the air out of the system.

 

2 hours ago, bigjohn said:

I thought the N279 valve was for cars with the aux heater - not normally fitted in the uk. It so the auxiliary heater only has to heat the heater matrix and not the whole cooling system.

 

Not sure about the v6 but on my humble 1.4 all pipes lead up towards the coolant tank including a small pipe from the top of the heater pipes so should be self bleeding. Normally after filling you keep squeezing the rad bottom hose to encourage the air out of the system.

 

Thanks

 

Re-reading the manual, you are right re the aux heater.  I am not getting the 9L capacity referred to in the engine training manual I have, so I assume I am just not triggering the thermostat for the engine block vanes.
 

The reservoir is high on the 3.6 as well. So yes, if running as an open system (cap off) it should let air escape. 

 

I have squeezed the hoses a lot. 
 

I have flushed at least part of it clean, so will just replace coolant and drive around with the heater on full. If I need to do another flush/replace I will put it down to experience. 

When I changed the radiator on my mkI Octavia I was surprised as to how little coolant went back in after draining the system from the bottom hose. A lot must have remained in the engine & interior heater. I had a lot left over - everything was fine though. On filling I ran with cap removed until the fans kicked in - squeezing bottom hose carefully every now and again. PS change any O rings.

 

Edited 26 April, 20224 yr by bigjohn