Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VZ over heating

Cams vz

Member
Joined
Jan 10, 2021
Messages
47
Reaction score
3
Points
8
Age
45
Location
Thomastown
Members Ride
VZ Commodore
Hi guys and girls I have a VZ alloytec 6 been driving for 2 years without a problem and today it got hot overheat came on dash and Auto Trans light on after I let it sit for a while opened the radiator cap and no water but has water in overflow bottle,,any ideas please
 

DavesSV6Tonner

Well-Known Member
Joined
Mar 25, 2019
Messages
629
Reaction score
1,486
Points
93
Location
Australia
Members Ride
VZ S V6 Cab & Chassis
Hi guys and girls I have a VZ alloytec 6 been driving for 2 years without a problem and today it got hot overheat came on dash and Auto Trans light on after I let it sit for a while opened the radiator cap and no water but has water in overflow bottle,,any ideas please

Fill up the cooling system with water and without starting the engine look for signs of water dripping, trickling or pouring from the engine or radiator.
I'm thinking the plastic radiator tank might have split suddenly draining all the coolant.
 

Cams vz

Member
Joined
Jan 10, 2021
Messages
47
Reaction score
3
Points
8
Age
45
Location
Thomastown
Members Ride
VZ Commodore
Fill up the cooling system with water and without starting the engine look for signs of water dripping, trickling or pouring from the engine or radiator.
I'm thinking the plastic radiator tank might have split suddenly draining all the coolant.
Ok thanks will let it sit for about 5 hours first that should be enough time do you think
 

wannaeatyourbrains

Well-Known Member
Joined
Sep 24, 2019
Messages
591
Reaction score
544
Points
93
Age
52
Location
Mecca
Members Ride
VZ Executive
The system is pressurised and sometimes it only leaks when hot. If you don't see anything coming out cold, start it and let it warm up, and reinspect.

Common culprits are the heater tap, the radiator cap, the hoses (including the one going to the coolant reservoir, which can break where it attaches to the outlet with the cap on it), where the plastic conjoins the aluminium on the radiator itself, and less commonly but still possibly the bleeder and drain taps on the radiator, the water pump and the gasket for said outlet. Could have sprung a leak from the radiator vanes too, I have seen that.

Still having trouble, let it cool down again, drain a bit out of it, pull the cap off of it, block the line to the coolant reservoir with your finger and blow and suck a bit there. If you can suck, she's leaking. Chances are you will hear the bubbling or squealing and pinpoint the location as well.

If you can't identify anything, change the radiator cap. Sometimes they look OK, but are not working. Were not really a good design.

When the radiator cap buggers up, it doesn't leak. It lets water out, but not back in again. The coolant is lost cause your reservoir fills up and overflows through the overflow hole on the side of it. Once you get an air pocket, it accelerates coolant loss.
 
Last edited:

Cams vz

Member
Joined
Jan 10, 2021
Messages
47
Reaction score
3
Points
8
Age
45
Location
Thomastown
Members Ride
VZ Commodore
Thanks it pushing water out the overflow hoses has pressure could it be as simple as the cap
 

wannaeatyourbrains

Well-Known Member
Joined
Sep 24, 2019
Messages
591
Reaction score
544
Points
93
Age
52
Location
Mecca
Members Ride
VZ Executive
Yes, very likely point of failure. Letting coolant then steam out, not sucking coolant back.
 
Top