Dropping temp while accelerating

[Daaaaavve]

Hey guys I have an 07 VE SS V bought it at the end of 2017 and the previous owner had done some work to it such as cam, otr, dyno tune, 3” exhaust with extractors and so on. She’s pushing out 482hp at the wheels last time it was tuned which was when the work was done. I’ve been real lazy with it and haven’t done anything major since. It ran fine for a while but after about 6 months it started running ice cold unless I was idling for a while, I was told that was down to a stuck open thermostat which I didn’t pay much notice to since I only drove to work and back and never thrashed it. Recently it did a full 180 and overheated at a set of lights and I had to get it towed. Then I was told the thermostat got stuck closed which I found a bit odd but I’m by no means a mechanic so who am I to argue. It got up to its normal temp for a couple days but after a while I noticed it was real slow to get to temp and then when it did it would drop slightly when I accelerated. Today I thought I’d try it out a bit more so pulling onto the freeway left it in 3rd and accelerated a bit harder and I got up to about 3.5k rpm and the temp dropped right back to cold but as soon as I took my foot off the throttle she rose straight back to normal running temp within a second. Does anyone know why this happens and will it be a problem in future? Like will I overheat again if I get stuck in traffic or at a set of lights for a while?

 

[_R_J_K_]

Does anyone know why this happens and will it be a problem in future?

Are you really asking this question?

 

[Daaaaavve]

Are you really asking this question?

Well yeah? There’s no way it should be fluctuating this much?

 

[_R_J_K_]

Did you replace the thermostat?

 

[Daaaaavve]

Did you replace the thermostat?

Yeah after it overheated at the lights I replaced the thermostat and after that it ran normally for a couple days but then all this started

 

[07GTS]

did u bleed it properly as the LS are a PITA to get all the air out easily, and is it actually overheating as the ect temp sensor can play up causing the gauge and ecu to get a higher reading

 

[_R_J_K_]

Info which you should have led with. Did you get a hi-flow or lower temp thermostat?

Without knowing specifics, the engine revving more will push more water through the radiator faster, the car going faster will push more air through the radiator. So these will likely make things colder, but you are right in that things shouldn't fluctuate that quickly.

 

[Daaaaavve]

did u bleed it properly as the LS are a PITA to get all the air out easily, and is it actually overheating as the ect temp sensor can play up causing the gauge and ecu to get a higher reading

I believe so but that’s always a possibility I guess, it’s not overheating not even breaking past the normal mark it sits at, but I’m worried with that much fluctuation it could do if I get stuck idling somewhere for some time

 

[Daaaaavve]

Info which you should have led with. Did you get a hi-flow or lower temp thermostat?

Without knowing specifics, the engine revving more will push more water through the radiator faster, the car going faster will push more air through the radiator. So these will likely make things colder, but you are right in that things shouldn't fluctuate that quickly.

My bad I tried so hard to get the cars whole story and I forgot probably the most important part
It’s a hi flow thermostat, believe the brand was tridon if I remember right
I would be fine with a little movement but to drop right back to cold and then spring back up to normal worries me a bit.

 

[_R_J_K_]

There's not a whole lot of point to hi flow thermostats on the street, particularly the way you say you drive it. There's a number of Tridon hi flow thermostats that also say they open at a lower temp, do you have the part number? I'm guessing you also have a massive aftermarket radiator?

Basically the first step in trouble shooting would be to go back to a stock thermostat. It would also be worth your while replacing the radiator cap too.