I had my LPG ecu retuned yesterday, the car runs better now, better changeover, loads a midrange torque, etc.....

But the Gas ECU reported the coolant temps @ 97 deg C, and the cooling fan wont cycle.
The gas man said I needed a new radiator, and he's done a few recently, but normally you'd see a post or two on here about it.

It does seem to run hot, The gauge sits about half way, the AC fan pulls the gauge down a Bees Dick, but hardly noticable. And very occasionally, (trying to keep up with Fooz) when holding low gears and pressing it up a hill, the needle will climb, I've never let it climb too high, and backed off at 2-3 marks above middle on the Gauge....
But the needle never goes above 1/2 regular running, but the heatsoak is tremendous, hot fenders, bonnet, strut brace, everything under the hood.

Is 97 too hot?
Is there a problem I should attend to?

TW-3.5 130,000km.

Start with a Thermostat

When the temp goes over halfway up the hill did you have the A/C running and also does the fan run when the A/C is running? When car is up to temp, both fans should run intermittantly. 97° isn't too hot, I could be wrong but I think the thermostat is 'meant' to maintain the coolant temp at 92-93°c.
Do a visual inspection of the condition of the front of the radiator for buildup of bugs/debris on it and see if the core itself isn't damaged/blocked restricting airflow.
But if you say the cooling fan isn't 'cycling' then it could be that. As above, Never hurts to replace thermostat either.

Start with a Thermostat

Thanks Mal, I popped the new and the old in a pot, The new was fine, the old barely moved 3mm @ Boiling....

Hopefully all good and fixed then lol

When moving at speed makes little difference if fans are working as the airflow will be far greater than the air from the fans

Nett result, I beleive its actually flowing now, (better than before) but, one fan kicks in and stays on @ idle, temp increases to almost 2 bars above normal(5 mins), then the other (AC Fan) kicks in and brings the temp down to 1/2. I watched this cycle 3 times.
When I'm driving the temp sits a little below 1/2, where I'd expect it.

Not really happy with this, any more thoughts....

should really sit at 1/2....

If the Thermostat was knackered for a while, could that affect waterpump/radiator blockages?

mate i had a simular issue - turns out it was the fan, low speed motor on the passanger side. make sure that both low and high speed are working plus the thermo.

you are correct it should sit in the middle and never really move!

coolent temp sensor would cause a check engine light although its only $40 for a new and pretty easy to change

How long since a coolant flush was done?
May not hurt to do a flush.
If that's not it, might also be a good idea to get an auto electrician to do a check on the fans.
Also as you mentioned the gas man said your radiator needs replacing, he may be right. But before throwing money at it maybe get a quote from a radiator specialist & get a pressure test done.

Yeah, couple of things to check, but I hate wasting money on problem finding, thats why I live here -

The gas guy also said the thermostat was fine -

I've never noticed the speeds change on the fans though.

I have replaced the sensor with a Tridon unit 2 weeks ago, about $12.00 from Stupor-cheap....
I flushed the radiator then, looks very good on the inside....

Marty, dads kj used to do a similar thing. It would creep up, especially when climing hills. And even on a 20degree day. Flushed the radiator, replaced thermostat, replaced both fans still didnt fix the problem.

Ended up buying a brand new radiator off ebay for $120 wacked that in and now its perfect. Fans very rarely come on.

We did test the thermostat, and it moved similar amounta to use.

Worth a test anyway :)

My Coolant Sensor cost $27 from Super Cheap Auto, but That doesn't have anything to do with controlling engine temp - it's an input to the ECU to indicate whether the engine requires a rich mixture for cold starting as far as I can tell. There's a separate 'Sender' for controlling the fans.

Mate the fan on the left has 2 speeds, disconnect the coolent temp sensor and both will turn on and they should be both on really high! Same should happen if you turn on the air con.

My low speed was not working as only one was on when i turned a/c. Doesn't cost anything to check either

Strangley enough, after a week with the new thermostat, it works perfectly now, needles always below half, one fan cuts in after being stationery for a while, then cuts out again....cycles beautifully...
Thanks for all the input..