Wildly fluctuating temperature after service on SV6

[daveminchang]

Hi, i got sick of paying $400 a service from the holden dealership for an oil change so I took my car to an RAA approved service place to do the oil, fuel and air filters.

that was about 2 weeks ago.

temperature before service was solid on two bars on the guage, but i notice over the last week that the temp is fluctuating quite rapidly between 3 bars (never gets cooler than that) and half way up. yesterday driving back from Victor harbour it was doing it a bit more noticely but was keeping cool because of air flow at 110.

when i stopped at lights it was fine for 1 min and then as i got up to 60 it went right up to 1 bar below the red zone within about 15 seconds and then dropped back down to between points 3 and 4 on the temp guage.

it wouldn't have been something stupid the service people have done would it?

checked coolant when got home and it's all there, no leaks from hoses that i can see. is it likely to be thermostat or temperature guage sender is faulty? seems to go up to fast to be real temperature. it's not just the guage on the dash as the thermo fan runs the whole time to cool it down so the car things it's hot.

ideas?

 

[ashbox]

maybe your rad cap is faulty, cos i know they pressure test to make sure there is no leaks in your cooling system.

it could be possible that the thermostat is stuck slightly closed.

which holden dealer did you use before going to an raa shop.

$400 is quite steep for a normal service, esp when i've only ever paid $250 for all mine and i'm also in adelaide

 

[impulsive]

yeah, go pull your radiator cap off, i blew one once, car went REALLY hot REALLY quickly, then dropped down and then really hot. Pull it off and have a look at it, when i pulled mine off the spring had compeltely broken and seperatedc from the cap. they are sold at repco and supercheap for about $30, pick yhourself up a spare too..

 

[jaz_777]

hey mate, my bet would be on the thermostat starting to **** itself, seems ti be happening more and more now, there a pain in the ass to change but, my mate had the same problem on his sv6, after much work replacing the thermostat the problem was fixed, would reccomend doing it before it completely shits itself and your stuck on the side of the road with a cooked engine

 

[the_trademarc]

yeah, go pull your radiator cap off, i blew one once, car went REALLY hot REALLY quickly, then dropped down and then really hot. Pull it off and have a look at it, when i pulled mine off the spring had compeltely broken and seperatedc from the cap. they are sold at repco and supercheap for about $30, pick yhourself up a spare too..

Holden sell em for $20 via Spare Parts

Definitely looks like the signs of a busted radiator cap. Should replace before you do the water pump too.
Would need to top up the radiator after too, and even coolant if its quite diluted

 

[ashbox]

just also beware, your water pump may go not long after you replace the cap, a few people are starting to report this happening.

mine went a month after the cap was replaced.

 

[daveminchang]

thanks...

thanks for the pointers people. i'll take a look at the radiator cap and see if i can figure out how to change the thermostat. i think i'll leave a dead water pump for a mechanic, hopefully it doesn't come to that.

thanks heaps for the feedback.

 

[ashbox]

the thermostat sits at the back of the motor just above the trans so that may also be a job for the mech.

 

[daveminchang]

ok thanks again. I took a look under the radiator cap this morn with a cool engine and it's got a black substance accumulated around the rubber so i hope that's not oil in the water. it's only done 90,000ks so surely i'm not going to have gasket or whatever problems already?

the spring seemed to spring alright. i'll just take it to the mechanics.

 

[the_trademarc]

ok thanks again. I took a look under the radiator cap this morn with a cool engine and it's got a black substance accumulated around the rubber so i hope that's not oil in the water. it's only done 90,000ks so surely i'm not going to have gasket or whatever problems already?

the spring seemed to spring alright. i'll just take it to the mechanics.

Mine had only done 45 when my radiator cap went, and then at 85. If you don't catch it soon, you could do a gasket and water pump pretty easily, because you're effectively running the car without anything to cool it down.