Brand new genuine nissan thermostat is set to 76.5deg C. It is quite a well made piece of kit as far as thermostats go and reasonably priced (just over $30). Also purchased a new gasket which nissan have changed to a metal composite rather than the old paper gaskets.
The thermostat removed from my vehicle was an adjustable item..!
As you can see, thats the thermostat sitting at room temperature. Someone has adjusted it to stay slightly open all the time (bad.. and why mine never seemed to get hot)
Anyway you can see easily on the adjustable thermostat how to keep it open further. Up the top of the assembly you can just see how there's a nut head and some thread which attaches to an adjustable stopper for the wax-pellet driven rod in the centre of the thermostat body. You screw that stopper up a bit to make it open later. this example has obviously been wound down a bit to push the thermostat open all the time.
Here are some clearer pics of what to do if you don't have an adjustable thermostat.
This is a genuine nissan, brand spanker thermo if you go and buy one for a 93 GQ 4.2L diesel manual.
Here's the friendly little blighter you need to shorten in order to make the thermostat open later. Be weary, on the genuine nissan item this appears to be a rather sturdy little rod of stainless steel.
So there you have it.
My GQ now runs with the temp gauge pretty much spot on half way on the factory gauge. It runs MUCH quieter, smoother and has more power in normal driving duties. Oil pressure has remained pretty much the same, if not a tad higher (factory gauge and sender which is a bit flakey).
Its around 28deg C in brisbane today and I didnt see the temp gauge move at all where it normally does (100km/hr in 4th gear, fanging up a steep hill, fanging in the traffic light grand prix etc). The viscous fan didn't turn on anywhere near as much as it used to - infact i didn't hear it engage once. We did stress test it by idling up at a standstill with aircon on in the driveway to see how hot it got, and just as the gauge started moving up above the half way mark the fan would kick in and remain on until the gauge dropped to about 1/3. Turning the heater on, the gauge simply just dropped down to 1/3 - oh and it actually works really well now.. just what i want in summer lol
)Sorry for the long post. I'm quite happy with the results of this small modification. I'll keep you all informed as to how it copes. I'm sure there'll be no problems - most of my cooling system has been replaced in the last year (rubbers and pump) so its in pretty good nick. I am still using the original BRASS radiator protected by an aircon radiator thing, flymesh, original 93 spec grille with no nissan badge and a bullbar.
Big cheers to "its a ford not a nissan" for this excerise. I hope it helps others.
