Coolant loss, no visible leaks

[veezedhead]

my vf2 sv6 started overheating at idle. I had to put 2.5L into the radiator but there was no visible signs of a leak from anywhere. Car ran fine for 4 days then same again, overheating at idle. I just put another 2.5L into the radiator. I’m hoping it is just the radiator cap. Any ideas? There’s no white residue under any of the caps. Cheers.

 

[Mike74ss]

Any signs of damp inside your front floor areas? A cooling system pressure test should be able to show up the problem.

 

[Sir Les]

How's the engine oil level on the dipstick? If coolant is leaking into the engine (God forbid), the level will be high and the oil will show signs of water contamination.

 

[Skylarking]

@veezedhead, welcome to JC's

Yes, as already mentioned, check engine oil level and condition and HVAC for leaks (foggy windscrean and sweet smell are a dead give away). But don't forghet to also check trans fluid level and condition if you've got an auto...

If all looks OK I'd change the radiator pressure cap (with a genuine Holden one) as they are known to cause unnoticed leaks after a while...
If you still have issues, or as a matter of course with teh above, do a coolant pressure test

 

[Flaggers]

I had the exact same issue, no leaks anywhere, no coolant on the ground etc. Was the radiator cap.

 

[veezedhead]

I had the exact same issue, no leaks anywhere, no coolant on the ground etc. Was the radiator cap.

I’m hoping it’s this, I just put in a new one. The old one didn’t any any seals inside of it.

 

[gossie]

Are you using the correct coolant as per your books?

 

[MattSAU2XR8]

Normally if coolant was going missing I'd be worried about it ending up in the transmission..... I imagine that since radiator is under high pressure and trans cooler is low pressure water could potentially flow in only one direction. Although if you have had to top up 2.5 litres I'm not sure this much would fit. Could probably wind out the fill level plug, either on the side, or int he bottom of the pan and see what comes out. Hopefully not milky.

 

[shane_3800]

It's probably got a leak somewhere like a thermostat housing.
2.5l won't be a cap.

 

[veezedhead]

I just noticed a slow drip leak from underneath the car, right in the middle around where the engine bay starts. Probably a drop every 20 seconds. I’ll take it in to get looked at.