Problems with the Thermostat?

[misdirection101]

Recently the temp gauge on my car starts to go above normal (75%-or higher). Everytime I pull over to check it out, the engine and coolant temp always feels normal. I jump back into the car and the guage is back down to normal. This has started to happen more and more frequently. Also just the other day, the gauge shot up all the way and gave me a check powertrain warning and I haven't driven it since then. I have done abit of research myself and from what I can tell, it's more than likely the thermostat, but I'm not sure what the checkpower train warning has come from. Possibly related to faulty thermo?

[impulsesv6]

replaced my thermo recently...
overflow bottle was constantly full and was constantly topping up the engine with coolant, but guage stayed on the 3rd line max... even with the charger

[Benboy]

Could be one of many causes. Take your car to a Cooling Specialist and have them pressure test your system. Only reliable way to identify if you have an overheating problem.

[misdirection101]

Got my thermostat replaced and still having the same problem, worse though I think, gauge goes up and down constantly

[impulsive]

check the cap for damage.. had to replace mine after it sent the car soaring hot

[Not_An_Abba_Fan]

Could be a faulty temp sensor. Would explain why the check powertrain light came on.

[IBLOWN]

Also check the thermo and A/C fan. If the thermo fan cuts in too late or is not swithcing to high speed it will do that.

If the A/C fan doesnt work (or not full speed) it will also do that when the A/C is on.

[slickrick]

Make sure that the thermostat was a genuine Holden item. Have fitted aftermarket ones and have had no end of trouble

[2005vzute]

seriously mate, replace your radiator cap, they're like 12 bux genuine or something, thats what i paid anyway...from working at holden it was extremely common to have te radiator caps buggered in them, deadset, they should just classify them as a wear and tear item like tyres koz they're that common...the cap is responsible for holding the pressure and allowing coolant to go into the overflow at the right time...if the cap isn't opening koz its buggered you could be putting alot of pressure in the cooling system and keeping very hot coolant in the system.

if this doesn't fix it and it does it again, have the car turned off, press mode and set at the same time, turn the car on...scroll through the menu using the mode button untill it gets to the coolant one..just check if how hot it is and come back with a reply and see if everyone else thinks it's too hot for the engine..i think it's normal to get up to about 105 on a normal drive...oh, and don't get scared when everything lights up and is set to half way.

cheers mate

[misdirection101]

yeah got it pressure tested couple weeks ago, turns out the cap needed replacing, but still having gauge problems. had my local holden dealers have a good look at it as well. they were stumped. the mechanic took it for a spin with the computer plugged into it, and he saw exactly what I was talking about. the coolant temp would stay at normal 100-105, but then would get really hot 124-126. they said either the temp sensor is faulty, or the thermostat that I got replaced is dodgy. so i'm getting the temp sensor replaced and hopefully that solves it... but i will keep you posted

[Davidcoolaye]

I had the same issue with my VX V6 a couple of weeks ago, only my temp gauge would go right up to hot mark and start beeping when i was stopped at lights or going through drive through. At first i thought it was the water pump getting old at 220,000kms but i wasn't sure so i asked the boys at my work, they said replace the thermostat see how it goes some said replace the radiator cap. I had replaced the rad cap 1month ago so i just threw a new thermostat in because they are like 9 bucks tops for genuine so why not. Still had the same problem so i asked my friend at holden if i could borrow a brand new temp sensor for the ecotec to see if that was my issue. Put it in only took about 10 minutes and done, problem solved never had a problem since. Hope that is the same problem for you because they are cheap and easy to put in. Good luck mate!

[misdirection101]

i took it for a quick spin today and fluid still travels through the upper radiator hose, so the thermostat must still be working, but yeah hopefully when i get the temperature sensor replaces, should be dandy

[FnomnaVZ]

On the alloytec, the thermostat is on the inlet side instead of the usual outlet side - so the fluid coming out of the top hose can still be hot without the thermostat opening I guess.

misdirection101, out of interest how oftern has the coolant been changed?

[misdirection101]

been topped up quite abit lately, but i'm not sure when exactly the coolant was changed

[misdirection101]

i would assume it's not a coolant problem if the gauge continuously goes up and down

[aquatribal]

hey everyone.
i have just experienced the same issues with my cooling system on the 175 allotec vz. one night in traffic the temp gauge and thermos went nuts a few times (in slow traffic),pulled over and the engine was quite cool ????? i got back on freewaY and everything went back to normal, temperature etc.(there was no loss of permformance may i add) when i got home,there was no coolant..and white goo on the oil cap, way more than just condensation.took the car to the mech the next day and 2480 dollars later ALL the gaskets in the cooling system, changed.heads removed and sent away for crack test, maching etc. they came back good thankfully,total engine flush and water pump was gone as well. 5 leaks during preesure test.it was like a fountain (i changed thermostat while i was having work done, to costly if it fails as well later on). even though i looked after my car well, and had it serviced when needed,check oil and water every week, i wasnt flushing the system enough, and probs not using the most suitable coolant for the alloytec . the coolant turns slighty acidic after 12 or so mths and eats everything slowly. the wrong coolant is , from what i hear and read, the cause of most premeture cooling system failures......

spose its a little like a human, not enough good liquid in it and it will slowly die....

good luck

[aquatribal]

the problem also, may i add, with the gaskets is that they are shim gaskets. this means there is multiple layers (3) i think, and the layers seperate when/if the coolant is contaminated, allowing water to leach into places it shouldnt be.....doesnt seem like a good gasket to choose but im sure some has logic to its use...like CLEAN YOUR COOLANT OUT MORE OFTEN, i hate logic...its always right...:P

[collos69]

same problem with me just after i installed an ss induction kit on it.

is there any temp sensors around the CAI? and where abouts are the temp sensors on the vz v6?

or is there any sensitive areas where if knocked coupld cause something like this?

appreciate any reply.

[misdirection101]

turns out all my over heating problems stems from busted heads.... i don't think the guy who had it before me took very good care of it . recently started pumping out alot of white smoke when the engine was running and has gotten worse over time. the engine ends up burning a lot of the coolant, which is why i always end up topping it up constantly. i'm getting a low km, second hand motor installed hopefully soon. mech reckons its gonna cost around about $4400 to get done.

[2005vzute]

daaaaaayyyyuuuuuuummmmmmmmmmmmm

[impulsesv6]

turns out all my over heating problems stems from busted heads.... i don't think the guy who had it before me took very good care of it . recently started pumping out alot of white smoke when the engine was running and has gotten worse over time. the engine ends up burning a lot of the coolant, which is why i always end up topping it up constantly. i'm getting a low km, second hand motor installed hopefully soon. mech reckons its gonna cost around about $4400 to get done.

wow... a brand new crate motor is 4300...

[RiCeY]

Coolant temp raising and dropping like that can be attributed to an air lock in your cooling system, common on alloytechs after a coolant flush/thermostat replacement.

I wouldnt be surprised if the heads were fine prior to the overheating and them being warped are a result of it, not the cause.

[NickVZThunder]

i had the same overheating problem on my VZ Thunder V6, reccently changed the waterpump and thermos, after re-assembling the wiring harness and manifolds and bleeding the system turned the ignition on started although the engine is running really rough and "checks power trans" is coming up on the dash. really stumped.

[sus steven]

Mine did the same thing it was just the coolant cap broken replaced it and no problem's

[vzchaser]

My car is a VZ ex-police station wagon and I have had cooling problems. In two of the cases the temperature guage shot up and after stopping for a while came pretty much straight down again. First time it was a cracked plastic radiator cap. The second time it was a blown water pump. Third, my mechanic hadn't bled the cooling system after changing the radiator, causing a localised pocket of steam in the system(and also hadn't topped up the auto trans oil). Like others, each time I suspected the thermostat. But here's something. It takes time for the water temperature in any system to be heated or cooled. If you get sudden gauge fluctuations eg peaking out then back to normal within a few minutes, water (and the hot metal of the engine)won't normally change temperature that quickly. You have a loss of pressure causing the problem not a thermostat problem. That is, you have a leak in you cooling system causing a loss of pressure (and coolant)which will spike your gauge... and you may not see much coolant leaking onto the ground, but your gauge will swing wildly. If not fixed you'll cook your engine...so certainly stop and top up your coolant. But in my case the cause of the problem wasn't the thermostat it was loss of pressure due to a leak causing the guage to peak and then return to normal relatively quickly.