Advice on coolant loss and head damage

[Clacker]

Hi all,

My brother's 2002 VX has coolant loss and he took it to a mechanic who said the heads are rooted. There was a rupture in the radiator. It's going to be a $4500 repair bill.

A couple of questions.

1) I thought the VX has a coolant fluid level or am I thinking of the VY?

2) I know the coolant temp sensor is up in the thermo housing. If the coolant level drops and the sensor starts to measure air temp, would that still show overheating on the gauge? What protection does the commodore have to let the driver know about coolant loss?

3) How do mechanics test for head damage? Do they have to repressurize the system to test if there is no sign of water in the oil?

I'm not suggesting the mechanic is dodgy but maybe he is just taking the safe way out.

Thanks for your help

[moose man]

1) I think you are asking about a coolant fluid level sensor in question 1, in which case, no previous commodore has one that I know of.

2. The only method of letting the driver know the car is overheating is the temperature guage. VY and VZ also have a warning message on the driver's display screen, but this is also only an overheat message. There is no coolant level indicator. The sensor will measure air (steam) temperature, and can be as good as it being immersed in coolant - depending on how much coolant is in the system (no coolant = no steam).

3. A mechanic can test for a cracked cylinder head a few ways, usually a combination of these;
- by testing for exhaust gas in the cooling system (the most accurate way)
- looking for coolant on the engine oil or vice-versa (not very specific)
- using a borescope down the spark plug hole and looking on the screen (also fairly accurate)
- by leak-down testing a cylinder (not very specific)
- compression testing (not very specific)

non-specific tests could indicate head gasket failures, piston ring failures or valve leaks.

[Sladdo]

VT-VX have a message come up on the odometre window saying HOT

[VX_SS]

jeez who ever quoted u 4500 for new heads better be putting on some pritty ausome heads but if not u could usually pick some stock ls1 heads up for no more than $1500 and then just switch the old spring and roller rockers over and anything else then its just a matter of putting them on with a new set of head gaskets witch will set u back about $200 and it should only take half a day to get the old heads of and put the new ones on.
the coolant tempreture sensor is on the left hand head towards the front of the head, i just broke mine... lol
and the only protection the vx has against coolant lose is ya temp gage and a beaping
oo yea this is all for a ls1 witch i asume u are talking about if not then it all should be cheaper although i wouldnt know were the temp gauge is on a v6

hope this helps

[Tsunamix]

Sorry, I think your getting done over.

It's totally impossible to tell exactly where the fault is, without taking the heads off. It could be heads, it could also be block, or head gasket. It could even be Manifold gaskets.

Compression testing will tell you if a pot has a leak, but that leak could be rings as well as gaskets or head.

Exhaust gas in the coolant is the most specific method - only way gas can get is head or block or gasket, with gasket most likeley.

All faults involving coolant loss will report as high temps on the temp gauge. Steam can be superheated over 1000 deg, while water (un pressurised) cannot be hetaed past 100 deg. Pressurised will go a bit higher, but steam pressure would blow steam out your radiator cap and overflow bottle, so it's hard to miss that, and if your coolant level was low, your temp sensor would pick up steam temps anyway.

If the car hasn't registered as overheating, and theres coolant loss, the most likely scenario is head gasket, or even inlet manifold gasket. Check your spark plugs. The ones with water in the pots will be brown, where normally they are blackish.

[Kurhas]

1)mm, i think he means the low coolant light around the tacho, which come on v8 vx.

2) get a second opinion, could be nothing, had my car overheat twice, one when my drive belt went and the other when my heater tap cracked on the freeway and coolant when everwhere. no harm in havin another mechanic look at it.