1HZ thermostat reading (1 Viewer)

[ardnez]

my thermostat reading stays below the half line after warming up and reaches half or higher when going up steep inclines but I’ve observed another HZJ73 and it stays at the half line after warming up, does my thermostat need replacing or which one is reading correctly?

 

[Gun Runner 5]

Never been a big fan of Toyota’s water temp. gauges. I always felt more comfortable installing a good after-market gauge.

 

[Willis]

1/3 is the sweet spot for 1HZ and most old 70s. This is about 175F which is probably what your thermostat is at, that other truck may have had a hotter thermostat.

It will get to 1/2 when going uphill, try not to go past that. 1HZ lug up hills and heat up fast.
1/2 on the gauge is about 190F

 

[ardnez]

1/3 is the sweet spot for 1HZ and most old 70s. This is about 175F which is probably what your thermostat is at, that other truck may have had a hotter thermostat.

It will get to 1/2 when going uphill, try not to go past that. 1HZ lug up hills and heat up fast.
1/2 on the gauge is about 190F

Valuable info and I was hoping for that answer, saves me time haha, but was willing to replace thermostat, fairly inexpensive.

In my previous post i mentioned how 1HZ was extremely slow up steep inclines and thats really the only time i manage to go up the half mark, think i should be ok in cases as such?

 

[roscoFJ73]

Thats not the "thermostat" reading. The thermostat is a device in the lower coolant inlet that opens or closes to let coolant flow.
You are looking at the temperature gauge.
Its ok to let it go to half or even if higher if you keep it out of the red. In good order, they can handle 120c for long periods.
Steep inclines need a lower gear and rpms around 2500-3000. It maybe slow but it will not overheat.

 

[coldtaco]

My factory gauge at half showed about 212F on the aux water temp gauge. I can’t imagine how hot red line would be. This was with the 2H turbo

 

[JDM Journeys]

I think an EGT guage is the best insurance you can add to a diesel, once you've gotten your cooling system up to par.

It acts like a distance early warning, in my experience. If EGTs are high and you ignore them, then the heat begins to build and suddenly your coolant temp is rising. Having a pyrometer allows you to back out of the throttle, or drop a gear on a hill in order to bring the temps down, and the engine is saved a "thermal event".

More important when boosted, but even for an NA I think EGT is important.