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Omega CD - Commodore VY | Random Overheating

snibles

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Hello mates!

I'm a old reader of the forums... but now i'm one more member! :)

I know that i should be joined before and not just now that I had a problem with my car, but I promise that I'll be more participative.

And let me say thank you to the Aussies, for sharing the Commodore with us!

I have a Omega CD 2004 black (Commodore VY, don't know if it's a Calais or Berlina...) that has around 88.000 KMs and it's been running fine until yesterday. The car was in the garage after one night, and I noticed a small amount (like a cup) of water in the floor under the car. I checked the water level and it was fine.

Today coming to work, i noticed that the temperature needle rises a little more than usual... but 10 seconds later came back to normal level (1/2 scale). When almost at my work the needle again spike up to the red zone, and a high temperature indicator popped up on the dash. Immediately I stopped the car, and like 6-10 seconds later, the needle started to came down, returning to 1/2 scale.

I searched and read some thread here about overheating, but not found a problem related to my...

I took the car to a Chevrolet Service Center and the technician just added more water on the coolant reservoir, and told me to watch if the temperature needle rises again.

As service and parts of a Commodore here in Brazil are EXTREMELY expensive, i would like to know if someone has any idea of what could be this problem. The guy, said that it could be the thermostat valve... and already told me that it's not a cheap service, since the thermostat is located behind (under) the engine... really?

Please excuse my poor English... :)

Thanks!
 

Sean880

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OK here are a few comments.

I find the description a little confusing as you indicated that initially there was no sign of low or depleted coolant levels (after checking coolant levels) but you later mentioned that the mechanic had to add coolant to your radiator.


1. If you see fluid under the car again check if it is condensation draining from the air conditioning system (which will occur after you park the car after running the aircon)
OR
if you have coolant leakage.
The coolant is green so drop a white kleenex tissue on the fluid. If the fluid is coolant then there will be a green stain on the tissue paper - assuming you have the correct green coolant fluid in the system.

2. If there is an external coolant leak it could be from a faulty radiator hose or heater hose, a faulty hose connection, a leaky system gasket, a faulty and worn radiator cap, a crack in one of the the plastic sections used in the construction of the radiator(requiring a new radiator to be fitted), a crack in the coolant reservoir bottle....... and so on. The coolant is circulating at considerable pressure so it only takes a small weak spot to expel coolant from the cooling system.

3. If coolant is leaking internally, the usual problem is a leaking/failed head gasket(s) and you will also likely find oil contamination in the radiator coolant. It does not look like you have this problem.

4. If sufficient coolant is leaking out you will get an overheating condition and according to your description of the problem there was a need to add coolant. Always check coolant levels in both the overflow bottle and the radiator by removing the radiator cap when the coolant is cold.

5. If you do not have an external or internal leak (that is producing a low fluid level and overheating) and the overheating is a random problem I would suspect a faulty thermostat. If the thermostat is intermittently sticking in the closed or partly closed position the coolant flow to and from the radiator will be impeded and the engine will overheat quickly.

You will also get an overheating condition if the water pump in the cooling system has failed (as they eventually do). However this will be a permanent (not intermittent) problem and overheating should occur every time you run the engine.

6. It is possible that you have both an external leak as well as a faulty thermostat. However the first stage is to have a thorough check for external leaks. As part of this process a routine pressure test should be performed on the cooling system. This is something the mechanic should have done when you took the vehicle to the CHEV service centre as this would have shown up if there was an external coolant leak somewhere in the system.

Cheers
 

snibles

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‪Hello Sean...‬

Thank your for the feedback!

I took the car to my dad's mechanic, and explained the problem to him.
He then, opened the radiator cap, and told me that it's wasn't with enough water. He completed the level, tested the pressure, and recommended that I change the radiator cap because it's starting to leak.

Since this, the car is running perfect... the temperature needle is steady at the middle of the mark... not getting hot anymore.

It turn out that the Chevrolet people, don't know where to put water in this car (me included). He told me to put water just in the yellow reservoir (i have read here to put water on the radiator). They didn't even bother to take the radiator cap off.

Seems like the problem is solved! :)

But i'll run a complete check again on the system to make sure that everything it's ok!

Thank you again!
 

TMM

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It turn out that the Chevrolet people, don't know where to put water in this car (me included). He told me to put water just in the yellow reservoir (i have read here to put water on the radiator). They didn't even bother to take the radiator cap off.
Under normal conditions it is ok to top up the coolant via the reservoir ("overflow bottle") - although you shouldn't ever need to if everything is normal!. If you let the overflow bottle go empty, or there is air in the cooling system (caused by a leak), filling up the overflow bottle won't work because there will be an air lock preventing coolant from being drawn out of the overflow bottle.

Quite often you will find that the radiator pressure tests ok, but when you run the car up to operating temperature it leaks. The plastic tanks on each end of the radiator develop cracks which open up and leak when they get hot. You can get just the tanks replaced, but it's usually more economical to just get a whole new radiator. It would also be a good opportunity to replace other parts of the cooling system which commonly fail, such as the thermostat and heater tap.

I would keep an eye on your coolant level. If it starts going down then it's probably the radiator. You may even be able to see some cracks in the plastic, or green staining caused by the leaking coolant.
 

snibles

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Under normal conditions it is ok to top up the coolant via the reservoir ("overflow bottle") - although you shouldn't ever need to if everything is normal!. If you let the overflow bottle go empty, or there is air in the cooling system (caused by a leak), filling up the overflow bottle won't work because there will be an air lock preventing coolant from being drawn out of the overflow bottle.

Quite often you will find that the radiator pressure tests ok, but when you run the car up to operating temperature it leaks. The plastic tanks on each end of the radiator develop cracks which open up and leak when they get hot. You can get just the tanks replaced, but it's usually more economical to just get a whole new radiator. It would also be a good opportunity to replace other parts of the cooling system which commonly fail, such as the thermostat and heater tap.

I would keep an eye on your coolant level. If it starts going down then it's probably the radiator. You may even be able to see some cracks in the plastic, or green staining caused by the leaking coolant.


Thanks for the feedback.

I'll check those points, and see what's happening... the radiator is filled almost only with water... the GM people, said to not put radiator coolant.. just water! They said that based on the car mileage (~ 88.000) the engine should run only on water. Is this info correct? I thought that radiator coolant was used at any moment.

But after we filled up with water, the car is running fine... temperature is steady at middle. But i'll take it to another checkup.

I have a feeling that the mechanics at the 3 GM dealers, have no idea of what they were talking...
 

VZCALAIS190

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That person from GM either must of had a few drinks earlier or he just dislikes you. All cars should have a coolant and water mixture in the cooling system otherwise your whole system is in risk of rusting.
 
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