[LS1] 03 WK Caprice overheating issues! At my wits end

[Giggity]

Hi guys n gals!

Three (yes effin three) years ago now, my radiator dumped all of its coolant and I coasted home about 400m, the temperature gauge never went over half, the car didnt overheat, all was ok, I replaced the radiator and the thermostat and was on my merry way, after this incident however Ive noticed that the temperature gauge will rise up to about 5mm over half (114c), sit there for about 20-30 seconds and then drop back down to a third (98-102C), now this will mainly do it on slower traffic and at traffic lights, I also thought I might add, that if its getting hot and I stop the car, leave it for a few minutes (lets say at a servo to fill up) then get back in and drive it, the first initial acceleration will cause the temperature gauge to leap up and drop back down fairly quickly.
Another thing is the longer I drive it, the higher the resting temperature becomes, so instead of it heating up to over half and then back to a third, itll be resting at half and heat up to 3/4.

The parts I have now replaced are
Radiator x 2 (now has a high performance alloy)
Thermostat x3
Waterpump
Overflow bottle cap
Coolant temperature sensor
Thermo fan relays
Aftermarket trans cooler
Has been TK Tested
Isnt losing a drop of coolant

The first picture is its resting temperature, the second is the hot zone

 

[Giggity]

Bump

 

[07GTS]

what is the vehicle data saying for temp is it actually getting hot or is the gauge not reading right..? temp senders by nature wont change with extreme movements unless there is air in the system causing steam pockets, the sensor being in the spot it is can get air pockets there so it needs to be bled properly, other then that u could try a mechanical temp gauge on the engine and see if it acts the same then it will at least give u an idea of where to look

 

[IBLOWN]

Have you done a compression test? Blown between cylinders can have that symptom.

 

[Giggity]

The temperature is what I said before, it says it on the dash and confirmed by heat gun, havent done a compression test yet, but the radiators I have put in there, Ive just realised, are only 26mm thick, tiny little things, factory is around 50mm by memory, so im going to put a oversized radiator in and see what happens.

 

[ALCMCQ]

Came out to the carpark Tuesday to see dripping from the radiator (cars only done 86,000klms!). New one installed that day - no temp gauge issues just drips - is this a common issue with Commodore radiators?

 

[Sandman]

Sounds like one of the fins was damaged putting the radiator in. I'd be going back to where it was installed.

 

[ALCMCQ]

It was the original that was leaking in the carpark (I mananged to get a new one fitted that day and it's been fine). I suppose the original lasted 11 years which is ok....still ~$550 lighter in the wallet..

 

[Giggity]

ALCMCQ thank you SO much for hijacking my post! really, keep it going!

As to the fins, they are fine, all been checked out, Im swapping the radiator for a really good one and seeing what happens