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Temperature Fluctuating

shonrand

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Hello All,

I bought an '03 Lumina S (middle-east spec, you know; normally aspirated 3800 V6), and the previous owner had the coolant system flushed and the thermostat replaced. The car's been running fine, but I noticed the temperature gauge fluctuating quite drastically today. There are no leaks visible or any steam, etc.

I'm thinking this is a sign that the coolant system might have air in it--do you agree? If so, my browsing through this forum (I used ye olde "search forum" button--wonderful creation, that) would indicate that I should just open the air vent valve atop the coolant outlet to release any air, right?

When the radiator cap is off and the car is running, the water is circulating so I know it's not the water pump acting up. Since the thermostat was just replaced, I assume that's not the problem. Are there any other possible culprits for the temp doing this? Bad radiator cap, maybe?

Thanks!
Shon
 

Brett_jjj

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The temp gauge should flunctuate a bit when stopped with the engine idling, it should get hotter up to a point where the cooling fans cut in and cool the system down again.. The temp gauge should sit around the same spot though when driving along. If its flunctuating a lot whilst driving along, then theres probably air in the system which needs bleeding out. To do this, first face the front of the car uphill, then get a plastic bottle and wrap the top of it where the cap thread is with electrical tape until you can seal the top of the bottle in the radiator cap opening. Cut the bottom off the bottle and push the top of the bottle into the radiator so the tape seals againt the opening, then fill the bottle with the mixed coolant and water, and start the engine and turn on the interior heater to full hot. This should bleed any trapped air out of the system as it idles, and because the coolant level in the cut off bottle is the highest point in the system, this then pushes most of the trapped air out of the system. Keep a good eye on the radiator overflow/expansion bottle for the next few days as it will probably take up some more coolant from the overflow/expansion bottle as more air escapes from the cooling system. Radiator caps are cheap to buy so its probably a good idea to replace it whilst your at it.
 

Pollushon

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I've found most Commodores to have very active temperature gauges. I like it, many folk don't, in fact some car manufacturers curb the gauge on purpose. Depends on what you were doing and the ambient temperature as Brett alluded to. A bit more info might help as to whether it's anything to worry about.

Did it go higher than halfway (or a few needle widths higher)?
Were you in stop start traffic?
Did you hear the thermo fan cut in when the temp rose?
Did it then drop back down?
What was the weather like over there when it happened? (I'm assuming warm to hot :))
 

mpower

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sounds like it needs to be bled to me.

my old VT V6 never fluctuated.
 

Big-Al

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try bleeding it but other than that, if it isn't boiling and it is a hot day it sounds like it is running just fine.

Another thing you could try is a coolant with less glycol in it as I doubt you will have issues with the coolant freezing. try 33% instead of 50% as distilled water is a better at shedding heat than glycol is.
 

mpower

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also check the hoses are in good condition and I wouldn't believe the previous owner either, thermostats are cheap.
 

markbaja

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I suggest bleeding the system, but as for the gauge moving, I've never seen the one in my vy move, only when getting up to temp obviously though.

I thought my gauge was stuffed, but even in engineering mode, the temp only goes to 93, maybe the occasional 94 in summer, but generally always sits on 92. This is a genuine Holden thermostat, so no idea why others fluctuate so much.

Sent from my GT-I9100 using Tapatalk 2
 

mpower

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I'm with you markbaja I've had a V6 (3.8) and 2 LS1's and the temp gauges all behave the same - very consistently.
 

shonrand

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I've found most Commodores to have very active temperature gauges. I like it, many folk don't, in fact some car manufacturers curb the gauge on purpose. Depends on what you were doing and the ambient temperature as Brett alluded to. A bit more info might help as to whether it's anything to worry about.

Did it go higher than halfway (or a few needle widths higher)?
Were you in stop start traffic?
Did you hear the thermo fan cut in when the temp rose?
Did it then drop back down?
What was the weather like over there when it happened? (I'm assuming warm to hot :))

It's never exactly cold here, but as it goes, it's not really hot yet: 90F/32C or something like that. This happened both while I was sitting still in a parking lot (for about 1 minute, not a long time) and while I was moving along at a regular speed of about 60-80kph. I didn't hear the fan kick in at any point more than any other point. It got close to red, then dropped back considerably below the middle, then moved up above the half way point, then dropped, etc. If it were only moving a little, hovering around the middle, I wouldn't be worried. This is wild variation. I'll try to get the air out today, since that seems the most likely culprit, and let you all know what happens.
 

Pollushon

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It's never exactly cold here, but as it goes, it's not really hot yet: 90F/32C or something like that. This happened both while I was sitting still in a parking lot (for about 1 minute, not a long time) and while I was moving along at a regular speed of about 60-80kph. I didn't hear the fan kick in at any point more than any other point. It got close to red, then dropped back considerably below the middle, then moved up above the half way point, then dropped, etc. If it were only moving a little, hovering around the middle, I wouldn't be worried. This is wild variation. I'll try to get the air out today, since that seems the most likely culprit, and let you all know what happens.

Yea okay, well that's a problem, shouldn't happen moving at that speed or get near the red. Admittedly I'm only experienced in the VN-VX but in my experience when the car isn't moving much and the temp is near the 30's (C) it's not unusual for the gauge to do the up down in time with the thermo fan to the halfway point and back to a quarter. Consistent driving though usually sees it barely budge from that 1/4 - 1/3 mark.

Anything Eco has a very high pressure system (25PSI/135KPA), hence the normality of the fluctuation I've described. Sounds like Holden went the inhibitor route on some/later models based on mpower and mark's comments and potentially it depends on your dash cluster setup, some gauges are quite small.
 
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