Cooling System Directions

[youremostwelcome]

G’day everybody,
Need a bit of a point in the direction of where to start. Was driving my ‘08 Lib GT (160,000 k’s) yesterday and pulled over to take a call (in a patchy signal area). At the end of the 10 minute call (car was idling the entire time), glanced at the temp gauge to see it flirting with being in the red zone. I had no real option but to continue as I was in the middle of nowhere. Quick check of coolant showed the expansion tank being about half full, but evidence of spill somewhere. Got the car up to speed and temp stayed pretty stable at the 2/3 level of the scale at 100kph (normally sits just below half). It wasn’t a hot day- was below 20 degrees Celsius.
Interestingly, going through a town at 50kph, the temp dropped to normal operating temp. Took it slow the rest of the way and made it home.
Having a look at the car now and it’s tricky to see where any leaks are coming from. There’s a bit of a spray through the engine bay (mostly on the pass. side timing cover, battery and headers) which might have been due to fans being involved. The expansion tank was also more or less empty, so it’s certainly losing coolant. I’ve also had it idling for 20 mins (with AC on) and temp is rock solid at operating temp. Thermo fans haven’t kicked in either.
Anyway, can’t see any loose fittings or cracked hoses. Removing rad cap, there’s coolant visible and circulating.
Any suggestions on common causes and where I should start looking? I’ve got a coolant funnel on its way to me to do a proper flush and refill without air in the system.
Thanks in advance!

[nvmylh]

Bypass your heater core and try again

[youremostwelcome]

Thanks for that. I'm reasonably sure it's the rad itself. I've got a pressure test kit on the way to confirm.
Angus

[bigBADbenny]

Clean it off and look for new spray.
Its very common for the stock plastic/ally rad to seperate and leak around 150k km.
I replaced mine with a stock aftermarket type from bursons and am due at 290k km for another.

Good idea to do both hoses and check/replace your accessory belts at the same time.

Also learn to completely bleed your coolant system.

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