68 replies to this topic

[MRLXSS]

Hey Guys,

We bought a VT for Maddy a few months back... We bought it cheap, knowing it had a cracked head or head gasket.

I replaced the heads and got it running again all sweet, thinking i had fixed the problem and we would now have a good car! How wrong was I!

The car would randomly shoot up to boiling then back down to normal, we initially thought that we had air-bubbles in the system, and it needed to be bled... I'm now an expert in bleeding these systems!! It still overheated randomly.

We put a new thermostat in, and i tested it in a boiling pot of water with a thermometer. All good! - Installed - No change... Still overheats.

At this point, I gave up and handballed it over to Maddy's dad to look at.

He found a leak from one of the hoses that he fixed and re-bled the system.... Still overheats!! When he had it up on Stands, he found that the pass floor was wet and coolant was leaking from what looked to be the Heater core! We thought this had to be the problem! Because when the car would overheat, the heater would go cold... It made sense!! So Maddy booked it in and had the core changed (and the A/C was also stuffed so that was fixed as well...) $1000 Later STILL frOckING OVERHEATS!!!!!!!!!!!!!!!!!!!!!!

We thought the core was the problem, and it fooled us for 3-4 days before overheating again.

So, over the weekend I did more tests... We noted that after everytime it was 'hot' we were able to add almost 2L of water to the system... So with a full radiator, i drove it till it got warm, then parked it at home running... After a few minutes, At least 500mls of coolant overflowed out of the overflow bottle. I took the bottle out and checked for cracks... No cracks it was all good...

I replaced the radiator cap for peace of mind and you guessed it... Still overheats!!!

When i say overheats.... The temp gauge quickly shoots up to half... then back to normal for a bit, then spikes up to 3/4's for say 20seconds, then drops back to normal... Then shoots up and the BEEP BEEP BEEP! To Hot! Keeping the car running, turning it off or driving makes no difference to the temp either...

I should also point out that the Radiator is new as well, was replaced just before we got the car... Maddys dad also pressured tested the system and it was all ok.

Does anyone have ANY idea what it could be?? I'm completely STUMPED and OVER IT!!!!!!!!!!

[Statler]

Good fun.. isn't it? lol

I presume it's an ecotec?

It is common for the temp gauge to go up to 1/2 when sitting in traffic.
At first i was alarmed, but all ecotecs seem to suffer from it.

The 'beep beep' alarm will sound as soon as the sender reads no water. It doesn't mean that the car is boiling. An air bubble in the system will trigger it.

Have you checked the temperature of the water when the alarm goes off?
Are the radiator hoses sucking in?

I think it is either air in the system, or a faulty radiator.

I'm comparing it to my VS, but i know of a VT which was suffering from the same thing & it turned out to be a faulty ECU.

Edited by Statler, 26 July 2010 - 01:41 PM.

[MRLXSS]

Yeah col, its an Ecotec.. Stupid motor! LOL

It Beeps when the temp gauge is hitting the Red mark on the Temp gauge... So i just assumed it was hot. But your right, when i pop the bonnet, its not all that hot.. (The Radiator cap is not even hot!) And it doesnt smell hot at all. Which is why everytime we just thought it was an air bubble.

The Radiator hoses don't suck in at all, just the standard puffed up and pressurized.

What surprised me is how quickly the coolant was being pumped to the overflow... But it didnt seem to suck it back in (Hence why i got the new radiator cap)

Currently, i have bypassed the overflow bottle, and just jammed a 2L bottle in there to watch how much coolant is going in and out... Murphy's law as well, it didnt spit any out for a change after a 15min drive. (where as it did before after a 3min drive)

[MRLXSS]

Thermofan relay, or a burnt connection to the same. That's what it was on our V6 anyways.

To check, put the A/C on, and the thermofan should come on. If not, have a look at the connections to the thermo fan relay and the relay itself. Under normal operating, the temp gauge will raise to up over half way till they come on.

Yeah, I thought that too Pat, The fans come on when the A/C is on though. And yesterday that made me jump 2 feet in the air when they came on when my head was in the engine bay haha!

Matt, i remember a mates VS was doing something similair and we changed the thermostat thinking it was the problem as it was intermitant thing but same as you no luck, we ended up changing th water pump and it fixed the problem . Not saying its your problem but food for thought ??

I made this suggestion as well to Maddys dad, who is a mechanic and reckons that the water pump will either visibly leak, or be noisy when it's let go.. But I'm starting to think we just change it anyway... for like $50 it might be a cheap fix eventually

Yeah, I am also thinking i will get the digital temp display up tonight and take it for a drive and see how it fluctuates... Apparently just hold Mode + Up on the dash and then flick through to the temps.

[TerrA LX]

Dirty condenser and or poor fitting (not seating correctly) radiator cap.

[MRLXSS]

Just bought a waterpump... Will fit it when it arrives. There is going to be the biggest 'I Told you so' if it does fix the problem... As i have been saying it from the start. She still didnt want to buy it... So i have paid for it and she can pay me back if it fixes the problem! If it doesn't... My loss haha.

[TerrA LX]

Hate to say it but I would think a bad pump would run hot constantly, not spike up and down.

[MRLXSS]

Watching the temp before (Digitally) it would run fine for a while, but then it was gradually building up to hot, then dropping back down, then up, then down again.

I might also try running it without the thermostat all together and see if that makes any difference.

[originalglenn]

Just bought a waterpump... Will fit it when it arrives. There is going to be the biggest 'I Told you so' if it does fix the problem... As i have been saying it from the start. She still didnt want to buy it... So i have paid for it and she can pay me back if it fixes the problem! If it doesn't... My loss haha.

oh oh sounds like famous last words " i told you and your dad it was the water pump"

are you planning on being celibate till her next birtday?

seriously though its not a fault in the gauge or sender is it?
and its probably worth getting a tk test from you local radiator shop to eliminate a cracked head/dodgy headgasket
it woulnt be the first time geting things fixed didnt work

[MRLXSS]

^^ Well, she is going to give the radiator mob who replaced the heater core a call first thing in the morning to get their opinion, they said it all tested fine. But who knows if they actually did the tests.

I'm not sure on the sender/gauge... I think i read somewhere else that the digital temperature readout, is read from a different point to the dash gauge. I did notice that the digital gauge was about 2-5 seconds ahead of what the dash gauge was reading.

[GTR469]

I had this problem on my VS and it turned out to be the sender for the gauge.

[mr5000]

geez didnt realise this was still goin is it on gas at all?

[TerrA LX]

Matt, i know you have a new cap but I have seen a hell of a lot these days that do not seat properly, if the cap can be rocked it is not tight enough to seal and pressure will not build, also if your condenser looks at all dirty it needs to be cleaned, the VR, VS, VT etc seemed to suffer easily from this, causing the temp to spike in traffic with the A/C on.
FYI I clean them with caustic based oven cleaner but don't leave it on too long as it eats alloy

[MRLXSS]

hmmm doesnt explain the water loss though , its one of those problems that you can always look back and say remember what a bugger that was, now pass me another beer

I know that once we fix the problem.. We are going to say 'why didnt we look at that in the first place!'

geez didnt realise this was still goin is it on gas at all?

I don't think its gas related... The gas convertor isnt freezing up when it's overheating (If it was low on coolant, it may do this?)

Matt, i know you have a new cap but I have seen a hell of a lot these days that do not seat properly, if the cap can be rocked it is not tight enough to seal and pressure will not build, also if your condenser looks at all dirty it needs to be cleaned, the VR, VS, VT etc seemed to suffer easily from this, causing the temp to spike in traffic with the A/C on.
FYI I clean them with caustic based oven cleaner but don't leave it on too long as it eats alloy

I'll double check the new cap again, the old one was very easy to remove and might have had the slightest wobble to it. The new one is firmer and the seals look bigger and a better design than the other cap (I read up about what each seal is designed for etc, and yeah, new cap looks like it would work better)

The condensor looks new and isn't dirt at all.. The temps are rising in all situations too, A/C off, on, Heater on, off etc

[TerrA LX]

If all else checks out fine then it is loosing pressure somewhere, it a rad shop pressure tested the system, not just for a minute, but several minutes then it must be the cap.

[MRLXSS]

^^ Yeah, that's exactly my thoughts too, hence getting the new cap... Would you believe i have no friends with a V6 Commodore i can borrow their working cap to test if our new one is faulty... They all drive V8's or F#@d's

[Statler]

Probably a silly question.... but did you fit a 'recovery' type cap?

[MRLXSS]

Also get them to test the system with the cap on by taking of the overflow hose and pressuring it through the overflow tip.This will tell you if the cap sealing or if the filler neck maybe damaged etc.


Does the heater now work effectivly??Its hot and doesnt cool of with maximum blower fan speed indercating lack of flow/corroded water pump impellor??

It works AWESOME when the car is all running fine, I noticed on last nights drive though, as soon as the gauge said it was overheating, the heater went cold and just blew cold air. Which triggered me to think, bad flow.

Probably a silly question.... but did you fit a 'recovery' type cap?

I just went to repco and asked for a radiator cap to suit a VT Commodore. It is a 135psi cap. not sure if recovery or non-recovery (Would have to double check, it's stamped on it yeah?)