Temperature guage fluctuating

[BigBlurter Lurker Find all posts View Profile Close BigBlurter]

Hi guys, I'm new to the forum so I hope I'm In the right place here, and new to owning a prado as of Sarurday😊.I have a 2006 1kz-Te and have heard of the cracked issue with these engines and hoping that I haven't bought a lemon!
I have noticed however when driving the temp guage sits just above 1/3 and when driving up a slight incline it can creep up to half way and then back on the descent. I've searched for the threads in this topic and found 1 but I want to make sure if this is normal or should I be getting it tested? What's others peoples 1kz temp guages doing? Is this normal or should it just be sitting at half way with damper Toyota thingy?

[samcanno Lurker Find all posts View Profile Close samcanno]

Hi guys, I'm new to the forum so I hope I'm In the right place here, and new to owning a prado as of Sarurday😊.I have a 2006 1kz-Te and have heard of the cracked issue with these engines and hoping that I haven't bought a lemon!
I have noticed however when driving the temp guage sits just above 1/3 and when driving up a slight incline it can creep up to half way and then back on the descent. I've searched for the threads in this topic and found 1 but I want to make sure if this is normal or should I be getting it tested? What's others peoples 1kz temp guages doing? Is this normal or should it just be sitting at half way with damper Toyota thingy?

Hi BB,
I'm in the same position except I have a 2001 90 series diesel , so I will be keen to hear the responses. I also recently purchased and noticed when going up a big hill that the temp goes up (slighty guessing maybe 5%) and then back to it's normal range when cruising down or on a straight.
The truck looks like its been cared for (log books, services etc) but it does have 293,000kms and I do have a boat that I will be towing so I am worried whether there is something more serious.
Speaking to a couple mechanically minded friends and they have suggested draining and replacing the coolant and observing any differences. Other things that could cause it water pump, thermostat?
Is it save to leave?

Thanks

[BigBlurter Lurker Find all posts View Profile Close BigBlurter]

Yep hoping myself it's nothing major either, I've heard the cracked head is common fault with the 1kz-Te and I'm hoping it's not that as that's not a cheap fix for a common fault!

[Foxo Junior Member Find all posts View Profile Close Foxo]

G'day,
My 2003 1KZ-TE has just reached 300 000ks and the temp gauge mainly stays at the base of the little thermometer icon, occasionally it will move halfway up the icon on a long climb, I've just towed an 18ft van to Cairns and back. I replaced the radiator at 230 000k and the water pump at 279000, as far as I know the 120 series IKZ doesn't normally suffer from head cracking provided you keep the cooling system in good shape.

Cheers,
Foxo.

[seenthelight Junior Member Find all posts View Profile Close seenthelight]

My 2003 1KZ-TE has just reached 330 000ks and has done this from day 1...When towing, traveling at 100+,on hot days and cold days
the gauge sits halfway...When driving at 80/90kph hot or cold the temp gauge drops about 3mm..
Hope this helps
Cheers
Geoff

[BigBlurter Lurker Find all posts View Profile Close BigBlurter]

Thanks fellas, good to hear that some are doing the same thing as mine �� Few.

[Rainman Advanced Member Find all posts View Profile Close Rainman]

My temperature gauge sits a fraction below half way all the time, the only time it ever moved above that (under load) was due to the radiator being blocked. Had it cleaned out filled with the long life coolant, hasnt moved since.

[Razorback81 Advanced Member Find all posts View Profile Close Razorback81]

I have a friend that has a 120 kz that has a cracked head
He couldn't afford to have it fixed
So he added a product called Liquid Intelligence while he's been saving up for the replacement head
That was 18mths ago
No change in temp no loss of coolant

[JimmyC Advanced Member Find all posts View Profile Close JimmyC]

sounds like the thermostat might be kaput

[Guest Close Guest]

Best to invest in an ELM327 OBD2 device and Android Torque Pro app to know exactly what the temps are. Best $20 spent.

[t303 Senior Member Find all posts View Profile Close t303]

I have a friend that has a 120 kz that has a cracked head
He couldn't afford to have it fixed
So he added a product called Liquid Intelligence while he's been saving up for the replacement head
That was 18mths ago
No change in temp no loss of coolant

If you must use "head/gasket in a can" there is a Rislone Head Gasket Fix that is becoming a favourite product of used car dealers. It is about $80 a bottle, but it seems to be doing a pretty good job. A lot of them are throwing a bottle in everything "just to be sure" (ie get it through warranty) and my mate in the trade says it doesn't seem to block up cooling systems too badly.

[BigBlurter Lurker Find all posts View Profile Close BigBlurter]

So has anyone else experienced their temp gauge rise a couple of mm's to half way when under load or up inclines in their 1kz's? Keen to hear if others are doing the same!

[t303 Senior Member Find all posts View Profile Close t303]

That is normal behaviour. The only problem is that the movement of the gauge is not proportional to the increase in coolant temp. The span of two to three needle widths at half way is an actual temp range (measured in the top rad hose) of about 55 to 95C. I have seen a peak at 106C (and I never hold the temp above 100C, IMHO not ideal for an alloy headed diesel) and the needle was not even over 3/4 on the gauge. Note where the temp sender is on the engine, it is measuring in the block somewhere near the thermostat, ie cooled water. I am measuring what is coming OUT of the head, so I know the temp of the head, not the radiator output! Personally, if it ever got into the red I would consider the chance of head damage a distinct possibility. I reckon if you have over 10-12yrs/200+km I would change the rad on spec (I did at 120K when I did the cyl head and it resulted in a drop of about 10C in the coolant temps). Some may disagree, but I am conservative by nature; reliability is my overriding priority.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Mine didn't move around town sat just under 1/2. Get it out on the freeway where it had to work and it would rise a mill or two but never went over 1/2. Turned out the head was cracked. Prior to it cracking the gauge never moved a mill. You will you will no if the heads stuffed as you will get back pressure in the overflow bottle causing it to fill up and over flow onto the ground. That's how mine was anyway and from what I read back then seemed to be common.. Cheers

[Mule Member Find all posts View Profile Close Mule]

It came as a revelation to me a few years back that car manufacturers (not just Toyota) programme their temperature gauges to pop up to just a fraction below the mid point on the gauge once the engine is warm and stay there (without any fluctuation) so long as the engine remains within set temperature parameters that represent most normal operating temperatures. I was told this but had dismissed it until I connected what is the equivalent of a scan gauge to the vehicle I had at the time and found while the instrument cluster temperature gauge was rock solid fixed on the one spot the actual temperature in the engine was fluctuating quite widely as you would expect dependent on engine load. So flat out up a steep hill the engine temp would hit around 100 c while coasting down hill the temp could be down as low as 70 or so yet the instrument cluster temp gauge did not budge one mm. I found it a little disappointing but I have been told that it was to stop neurotic owners showing up to service departments complaining that the engine was running at a different temperature to normal when in reality all was well.