Coolant

[stainesy]

a week or so ago my thermostat packed up and i had to drain some water and fit a new one. since then i have only used the car to go to the shops and back and one 15 mile trip to my mums.
but on saterday i drove to london and back twice and clocked up nearly 200 miles.
i got in my car this morning and half way to work the coolant light came on.
when i checked the coolant it was right at the bottom of the expansion tank.
could this be because there may have been air in the system and it needed a good long trip to get it all to the top?

also have noticed sometimes when iv been driving and stop there is a small hiss from my coolant filler cap like its releasing presure but the temp is fine and the car runs fine. its a brand new cap.

any ideas?

[Vikingxl]

Could be or could be something like the rubber seal on the tank filler has perishes and when you removed it its not sealing anymore.Or check the hose that connects to it as that perishes as well causing a slow and small leak.

[chow]

try bleeding the system properly, sounds like you could have air trapped in the system

[Rufe]

yip, sounds like an air lock to me too, needs bleeding and should be ok.

[stainesy]

its a brand new filler cap so dout its perished. im going to keep an eye on the level and see if it drops again.
if it does then sumits rong if it dont then it must have been trapped air

[siamblue]

Stainsey did you let the car warm up with the cap off? just as the coolant starts to bubble put the cap back on, you will feel the top hose warm up before the stat opens, then let her cool down and re chack level,

Gary.

PS bolt is now in the post.

[princepugh]

My V70 P1 had the same issue, turned out there was a hairline crack in the nozzle on the reservoir (which the rubber hose clips onto), replaced the reservoir, sorted.
Sounds like the advice re air in the system might be more applicable in your case though.