VE ly7 loosing coolant out overflow

[Douglas125]

hey guys im at a bit of a loss with my ly7. since i bought it ive noticed that it has been pushing coolant out of the overflow. Ive had my mechanic do a TK test which came back negative, i have also replaced the thermostat, water pump, coolant temp sensor and fitted a new genuine filler cap. It only loses coolant when the ac is off, ie when the thermo fans arent on, when it reaches around 104 degrees coolant and steam start to come out the overflow. is it possible that i have a leak somewhere which is lowering the coolants boiling point, or is my head stuffed.

as a side note i can bleed the system fine with no bubbles, not coolant in oil etc. my mechanic did say that there was a leak out of the filler neck when he was pressure testing the system but was well above 20psi so he didnt seem to think it was the issue

motor has around 150,000ks

any help would be greatly appreciated

 

[krusing]

2 items I found with my LY7, (Adventra)

1) I replaced the filler inlet, from a o-ring type coolant cap, to a spring loaded type coolant cap, because where the o-ring was located, it had corroded,
I would say that is why it wouldn't seal correctly,
After I replaced that, (in which I replaced the seal & o-ring on the filler net unit) (item 3 & 4) it fixed all the leaks on the inlet,

2) I replaced the the 2 o-rings on the heater pipes, and the o-ring on the supply pipe to the thermostat housing.

But recently when I was heading to Echuca and back home, I had a very similar issue with it over flowing from the coolant reservoir,
Being I could hear it boiling in the reservoir, when I turned the engine off, and it was leaking onto the ground.
So put it down to the thermostat,
And have since replaced the thermostat with a Gates 82c unit,
and its no longer boiling/gurgling in the reservoir, and running a bit cooler.

 

[Lex]

my mechanic did say that there was a leak out of the filler neck

There's your problem.
If you don't take any notice of your mechanic, why come here & waste our time?

 

[Douglas125]

There's your problem.
If you don't take any notice of your mechanic, why come here & waste our time?

yeah shouldve added that he didnt think it was the issue because it only started leaking above 30psi

 

[Douglas125]

2 items I found with my LY7, (Adventra)

1) I replaced the filler inlet, from a o-ring type coolant cap, to a spring loaded type coolant cap, because where the o-ring was located, it had corroded,
I would say that is why it wouldn't seal correctly,
After I replaced that, (in which I replaced the seal & o-ring on the filler net unit) (item 3 & 4) it fixed all the leaks on the inlet,
View attachment 267435
2) I replaced the the 2 o-rings on the heater pipes, and the o-ring on the supply pipe to the thermostat housing.
View attachment 267436

But recently when I was heading to Echuca and back home, I had a very similar issue with it over flowing from the coolant reservoir,
Being I could hear it boiling in the reservoir, when I turned the engine off, and it was leaking onto the ground.
So put it down to the thermostat,

And have since replaced the thermostat with a Gates 82c unit,
and its no longer boiling/gurgling in the reservoir, and running a bit cooler.

thanks for your help mate

 

[Lex]

yeah shouldve added that he didnt think it was the issue because it only started leaking above 30psi

Take notice of @krusing, he knows what he's talking about!

 

[Fu Manchu]

It shouldn’t be leaking.

Also the coolant is going out and not back in. That’s controlled by the cap. That’s why it’s overflowing.

I’d just replace the filler assembly as everyone is suggesting.

 

[Douglas125]

It shouldn’t be leaking.

Also the coolant is going out and not back in. That’s controlled by the cap. That’s why it’s overflowing.

I’d just replace the filler assembly as everyone is suggesting.

thanks mate, if there was a leak wouldn't that mean that the system would have no vaccum, which would explain why it isnt pulling coolant back in?

 

[Fu Manchu]

thanks mate, if there was a leak wouldn't that mean that the system would have no vaccum, which would explain why it isnt pulling coolant back in?

Possibly but depends on the scale of the leak.

Either way the repair is all part of the same job. Replace the filler and the o-rings. I say replace the filler, get a good eye on the state of the filler cap seat. If it’s all corroded and no longer smooth, time to replace. You might find it’s ok in which case you just replace the o-rings.

Theres a walk through I wrote up for various cooling system jobs in the forums “How To” section.

The cap is $30 genuine. It’s worth changing it.

@krusing solved some headaches with his. Good advice. He recently found something interesting with the thermostats.

 

[krusing]

thanks mate, if there was a leak wouldn't that mean that the system would have no vaccum, which would explain why it isnt pulling coolant back in?

Yes