Metro 1.4 Auto (M reg)... the header tank had a load of brownish grey
sludge in it, and I have taken it off and cleaned it out. 

What causes it?

Assuming that this muck is also elsewhere in the cooling system is
there anything I can do to flush it out?

Thanks

"alo"  wrote in message 
news:liiff1peukmnile7tl7u36featnkn2oe8f@4ax.com...

> Metro 1.4 Auto (M reg)... the header tank had a load of brownish grey
> sludge in it, and I have taken it off and cleaned it out.
>
> What causes it?
>
> Assuming that this muck is also elsewhere in the cooling system is
> there anything I can do to flush it out?


It can be caused either by mixing the wrong kinds of antifreeze together or 
alternatively its oil. Oil would tend to mean your head gasket is on its way 
south. Suggest you get a pressure test done on the cooling system, that 
should tell you.

I.

alo  wrote in news:liiff1peukmnile7tl7u36featnkn2oe8f@
4ax.com:


> Metro 1.4 Auto (M reg)... the header tank had a load of brownish grey
> sludge in it, and I have taken it off and cleaned it out. 
> 
> What causes it?


Negligence with regard to changing the coolant regularly. A very bad thing 
with these engines, I'm afraid. Has it had a new head gasket, by any 
chance?


> Assuming that this muck is also elsewhere in the cooling system is
> there anything I can do to flush it out?
> 

Drain the coolant. Remove the thermostat. Flush the engine through both 
ways with a hosepipe. Do it with the heater set at cold first, then again 
set at hot. No point in flushing excess crap through the heater matrix. 
Repeat same process for radiator. That should clear most of it. As it's 
summer, you could add a flushing agent and refill it with just water, then 
run it for a week and change it again with anti-freeze. Normal anti-freeze 
needs changing every two years because after this it stops protecting the 
engine from rust, hence your rusty brown water.

BTW, don't forget to replace the thermostat after you've flushed the 
engine.

-- 
Stuart Sharp

The message 
from alo  contains these words:


> What causes it?


Most likely oil. That engine is notorious for failing head gaskets. Fix
before it gets worse.

-- 
Skipweasel.
Ivor Cutler - "Never knowingly understood."