Header tank-white"stuff" residue in area.
 

My 2004V6 ZT has what I describe as a "sputter" of chalky white drops in the header tank overflow area. There is no measurable loss of coolant. It appears to be a teaspoonful of liquid at most. Any ideas? Chris.

You mean a milk-like liquid?
If it's around the filler neck area, it must have been ejected through the relief valve in the cap. Does the coolant look clear and pink (or blue or green, depending on your antifreeze) or is it like milk too?
Is the coolant level at the MAX mark when cold?
Does your slow speed cooling fan work as it should? (Do the Demist Test).

TC

Yes its in that area and I would describe it as milky, well chalky, the level is about 2mm max above the high marker and I will check the colour of the coolant and do the fan check tomorrow. Thanks. Chris.S

The coolant should be transparent and with a colour dependent on the antifreeze used. Milky/chalky sounds like it's opaque and either emulsified or it contains a dispersion of fine solids. If so, it needs investigation. As a minimum, the coolant should be drained, the system flushed with a hosepipe and replaced. Old coolant will eventually become cloudy white/grey as the inhibitors disappear and corrosion sets in. Report back on the other things and I'm sure you'll get plenty of advice.

TC

I have mislead you! my reference "milky well chalky" was to the dried deposits on the header tank and area. As I said its a tiny amount. The service history says "white substance spilling out of exp. tank" carried out pressure test of coolant system. passes block and pressure test" that was in Sept 2016. I have changed the header tank cap in the last week but no change. Will get back when Ive done the other checks. Chris.S. PS "Cyrano" really??

Checked the coolant in the header tank, clear pinkish in colour, no granular feel to it on the fingers. Not done the the Demist test yet. Chris.S.

How regularly do you use the car:shrug: Reason I ask, is, after not using mine for a while, then a couple of short runs, I've had the "milky" deposits but after a long run, it just burns off:shrug: Condensation usually:cool:

Drops of OAT based coolant will evaporate off to leave a whitish-pinkish deposit/crust. It sounds like there's been a small ejection from the relief valve onto the top of the header. The results of the Demist test for cooling fan operation may add more info on the case.

TC

today (Monday13th Feb)Did about 30miles stopped for about 90mins, checked the header tank area,yes more white stuff and as you say looks to have come from the filler cap area. Did the demist test? engine on, demist on, checked from front of car nothing for a couple of minutes then fan starts big whoosh noise for 5 secs. then stops, then couple of minutes and whoosh fan goes again for 5secs then stops. As a matter of interest I can see there is a silver coloured "whatsit" on/near the fan- not a gold one as 'Jules' sorry I cant remember the name of it! Chris.S.

Well found the appropriate information on this site, it appears my slow speed is not operating and what I have described is the fast speed.cycling. New resistor required as per Jules, would that be the correct finding? Feel abit stupid but I did search but didn't find the info. Not always up to speed- anyway thanks to all for your help. Chris. S.