Gq coolant issue

[mark89]

G'day have a td42 and for about last 10k has been occasionally using coolant out of radiator and iv noticed its spitting out of overflow, now iv replaced thermostat and radiator cap and hose from radiator to overflow and occasionally will get hot and need to top a litre odd up in radiator yet overflow stays full (bit over full actually) and green, have had it pressure tested nothing came up i replaced and upgraded radiator 40 thous ago but Gona do hoses and flush/bleed system this weekend but unsure what it could be? Sees fair few long trips and I highly doubt it's the head/gasket. Any input welcome just frustrating me to no belief!!!

[Robo]

When the pressure test was done, was it checked for traces of fuel in cooling system?.
you may have a faulty cap that's allowing pressure out but not recovering once engine has cooled.
check how much fluid is in overflow when ya park next and then recheck once cooled.
if level has not changed, check/replace cap, and inspect retighten hoses etc including the recovery hose.
you could also do the coke bottle trick below to help check for problems

when you flush bleed etc, park on a slope uphill to make the radiator upper most point if possible.
use a coke bottle inverted as a funnel.
try keeping bottle sealed in filler neck as this more than helps the process.
turn heater on to full position.
then refill it slowly something like 1 ltr per min.
filling fast can trap alot of air in the system making bleeding a pain in the butt.
keep track of liters you put in to help ensure you have enough before you turn it over
once you are satisfied you have enough, bleed it of air as per manual instructs.

have coolant level a little inside the bottle this should make the highest point above the engine etc.
you then should see some bubbles in the bottle for a short duration.
if bubbles are constant, well lets hope not.