1hz getting hot under load

[terrano]

So we just moved from Ashburton down to Tarras central Otago. I drove the cruiser down with a trailer on behind, just a small one loaded with tools ect from garage so not too heavy.
It seemed to get hot when i was labouring up hills, even on the long straits through Twizel the gauge would be a bit up and down. Yet over the Lindis pass i thought #### it gave it shit to get up the hills and the gauge hardly moved
Checked all the levels when i arrived hasnt used a drop of oil or water, over flow was still on the full mark so hasnt been spitting water out. At one point the gauge went all the way to the top red than dropped back down to half way instantly.
Its happened to me once before going up the ski field road, yet ive done plenty of other trips and it seems fine.

Any ideas what it could be? Viscous fan seems to be working, water pump does seem a bit loose so i will be doing this, will get the radiator checked and cleaned.

[kbushnz]

At one point the gauge went all the way to the top red than dropped back down to half way instantly.

Possibly a stuck thermostat ....

If you labour it, she will get hot.. Need to let it rev freely....

[slide]

red than dropped back down to half way instantly.
.

Or faulty guage?

[mudlva]

Imho i think that you need to do a maneul check. Ie. When its reading supper hot pull over and check the radiator and motor. Preferably with a infared temperature reading tool.
That way if the thermostat is faulty then you will see a temp dif between the motor and rad. Or see of theres an over heating issue at all. If not then its a new sencer output or gauge

[ski]

I have had a few problems with my 1hz,Is the viscous fan screaming and pumping the air, some seem ok but until you stick a new one in then you are just guessing?, my gauge would go up and down on the hills would move in 25% segments. what's in front radiator, is it partially blocked so air is not being drawn ??. I used a thermo gun too. Mine was fine on the flat but point up to the hills and all changed. I would look at air flow??. Cheers

[terrano]

I will have to see if i can get a thermal gun thing, when it did it too me the first time i pulled over and checked under the bonnet and nothing seemed excessively hot from just touching things. I think it may be just trial and error until i fix it Water pump and radiator flush and check i will definitely be doing so will get that done first.

[Mehrts]

If in doubt, get yourself an aftermarket water temp gauge to prove/disprove the reading on the factory temp gauge for some peace of mind.

Plus you can see exactly what temperature things are sitting at, instead of mid way along an unknown bar.