air in Alfa 75 cooling system

[Alfamania]

Hey Guys,

Is there a special procedure to get rid of air in my cooling system in my v6 Alfa 75. I noticed when changing the temperature on my climate control fluctuates my engine temp, meaning not circulating properly? Any advice please? Thank you

I can see there is a air bleed bolt on the thermostat housing....do i just loosen the bolt while filling up?

Thanks

Alex

[shiny_car]

There's some tips in this thread from alfabb.com forums:
http://www.alfabb.com/bb/forums/milano-75-1985-1993/150928-refilling-coolant-after-replacing-electric-fan-switch.html

...including:
*massaging the radiator/coolant hoses sending air to the expansion tank
*having heater controls on 'hot' (ie: circulate coolant into cabin heat exchanger)
*using the bleed screw atop the thermostat

[Alfamania]

Fixed, thank you. I also need advice on coolant mixture please? should it be green 50/50 mix? Thanks 

[Alfamania]

Apparently the expansion tank cap is rated at 0.7 pressure. Does anybody know if this is correct? Some people reckon there are also 1.0 ones?

[shiny_car]

Fixed, thank you. I also need advice on coolant mixture please? should it be green 50/50 mix? Thanks 

Green or red, doesn't matter. BUT THEY ARE NOT COMPATIBLE WITH EACH OTHER. Generally, easiest to stick with what has been used before, unless you do a thorough flush of the whole system. If accidentally mixed together (green and red), it can precipitate.

The workshop manual suggests a 3.6:6.4 ratio (ie: 3.6L coolant concentrate + 6.4L distilled water = 10L total). Doesn't have to be exact. Nulon (for example) suggest between 33:67 to 50:50.

Apparently the expansion tank cap is rated at 0.7 pressure. Does anybody know if this is correct? Some people reckon there are also 1.0 ones?

OE spec is 0.7 bar. 1.0 bar is easier to find. If you are using a genuine/original expansion tank in good condition, 1.0 is fine.

If you have an aftermarket expansion tank, these are apparently not as well constructed, and can possibly split/leak. As such, it is recommended to stick with 0.7 bar.

[Alfamania]

I have a genuine expansion and the Cap too. It says 0.7, Cheers

[Alfamania]

ok so took it for a test drive. Now what happens is the temp fluctuates between 82 and 90 while driving. When stationary the temp seems to drop a bit?


Could It be because of a wrong water to coolant ratio? I doubt it though

[Beatle]

Fluctuations as you describe won't be related to the actual coolant type/mix.  When you say fluctuate, do you mean the needle jumps or drops suddenly, or is it a gradual change?

If it's sudden, I'd suggest either:

• Air in the system (still)
  Faulty guage
  Faulty sender
  Loose connection
  Bad earth

If it's gradual it could be normal, or maybe that the fan on/off cycle is a little out of spec (coming on too late, staying on too long).  Do you have a thermostat installed?

I find that most Alfa gauges, even if inaccurate, tend to read more directly than most modern gauges.  Modern gauging systems are usually designed with a dead spot (null) around the normal range so that constant fluctuations don't alarm the owners (and result in cars going back for warranty work).   People jump from a modern car into an older Alfa and the gauges actually move linearly with the temp (or oil pressure) and it's alarming.

[Alfamania]

Air in the system....all good now, thank you