possible faulty temp gauge?

Gday all,
i am wondering if the stock temp gauge in GQ's ( TB42) could be classified as being accurate & reliable? i have read a few posts about the oil gauges that have suggested ditching them for after market ones, so are the temp gauges the same? the reason i ask is that i have just had the head replaced ( after already doing the water pump,repair & flush radiator, new thermostat, hose's, all new gaskets through the auto ) & when i took it for a drive it was sitting between 1/2 & 3/4 on the gauge on flat roads & then when i struck a small hill it shot up to just below hot.
i took it back to the radiator guy who checked it over & he was stumped as the system had lost no coolant & hadn't even over flowed into the over flow tank. we left it idling in the sun on a 33deg day for 1/2 hour & it didn't move from between the 1/2 & 3/4 mark. so he has said i may need to get the gauge tested & re-calibrated ( didn't know you could), or maybe a new sender.
is this normal as this is my first nissan so i have no idea!!
all help would be appreciated
cheers

Mine used to do that mate - the gauges aren't overly spot on, but accurate enough that when it climbs like that it raises the alarm bells. Any "obstacles" in front of the radiator? Spotties, air con radiator, oil cooler, power steering cooler, etc? They all restrict air flow and when under load (like up a hill) and subsequently it heats up.

What sort of fan do you have (thermo or normal viscous hub)? Have you. Heckled them and the fan blades themselves?

You could try a cooler thermostat (I have one and it makes a big difference) but check the cooling system thoroughly first - fix any issue before masking it with a bandaid fix.

Good luck with it boss - no doubt others will have input here also.

I just had a play around with mine and found the fan on backwards it might be worth checking.
Also the silicon oil in the clutch fan can go bad causing the fan to be restrictive at high speed as well.
Funny thing was i never had a problem until i fitted the radiator shroud up.

I purchased a 100 ohm wire wound pot from http://www.wiltronics.com.au/index.php for under $10 and use it to test my gauges to the figures in the manual.
I found my temperature gauge was sticking half way, tested the replacement before being installed and now it all works good.
A handy tool for $10

Jeff C

hey voodoorick, I ended up replacing my temp gauge with aftermarket one for same reason - wasn't sure whether I could rely on it or not.
Apparently the temp on the old GQ's is a bit of a pain the butt. I have heard that for reasons unknown they can run really hot whether everything is in good nick or not. I had dramas with my td42 getting hot on hills, did the thermostat, fan silicon, flush etc. Finally put a new radiator in. It still runs on the warm side but is stable now at about 80 - 90 degrees.
Good luck mate

Viscous hub repair first. Oil is $40 and your own labour. Or $100 if someon else does it. Probably cheapest 1st option.
Mark

you can also buy cheapish temp guage that has the actual temp read out (not just hot or cold) and just plum it into the sender socket, run it to see what the thermostat is doing.

anybody heard of instead of a thermostadt a plate with certain size holes in it , i am just a newbie restoring a 89 maverick and the thermostadt was missing , after hearing of this bush mechanic trick thought i would try it mine runs at about 1/3 maybe a scratch more on the gauge dosent spit water into the overflow seems warm enough but in cold conditions like today noticed a lot of condensation coming from exhaust so maybe its too cold inside on cold days might need to stick a mat between radiator and grill to warm it up a bit and make another plate with a smaller hole , hey its only guess work .

Just buy a genuine thermostat.
They circulate coolant through the engine block only until it warms up then it closes off engine circulation and forces it through the radiator.

Hey mate,
I had similar problems with my 88 GQ petrol/gas 4.2 carby. I found the temp sensor was loose and giving false readings, I soldered up the sensor and now it works fine, just reads slightly higher than standard because of the extra resistance through the connection. I still had a cooling problem though with the coolant overflowing regularly on my trip to work (which is 50km's + btw). I had the radiator out and flushed it out and found it was 10%-20% blocked, I then had the whole system pressure flushed and a new thermostat housing and thermostat fitted. The system now runs fine and cycles at the correct temperatures. The only time I have problems now is extended periods at 100km/h plus, when the guage will creep up. If anyone has any reasonsfor this I would like to hear them but at the moment I assume its just the 35's and a few too many spotties at the front that probably dnt help either.

G'day all TJ here.. Hate to bring up an old thread but I would like pols opinion about the thermo gauge mine barley gets to half it's sits at about a quarter the hole time..? Engine warms up fine n idles fine after it warms up just the gauge doesn't move much..!

Quote:

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Originally Posted by 97_gq_lwb

Just buy a genuine thermostat.
They circulate coolant through the engine block only until it warms up then it closes off engine circulation and forces it through the radiator.

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Yep and check that it works, by putting it in a pot of near boiling water, it should open. I have had a brand new thermostat nearly cook a reco engine. (Although the thermostat was not a genuine)

When the car is running hot the viscous fan should kick in and the fan noise should be noticeable. Some you can add oil (diesel ones), some you can't )often petrol ones) if it is not working correctly. Guages I have always found to be reliable. Also a cheap core in your radiator can cause it to run hotter than normal.

The fan does kick it once its been sitting there so guessing the thermo works..?