I think you just need to put more miles on it, rebuilt engines expierence alot of friction in the cylinders between the piston rings and the freshly honed cylinder wall. Untill the rings bed in it's going to run hot. I installed an electric cooling fan that helped alot plus late night runs up and down the interstate.

Does anyone know how to get a hold of a genuine Nissan 160 degree thermostat? It seems that Nissan only carries the 170 and 180 degree ones these days. The only one I see on ebay is $55

Autozone carries a 160 degree thermostat for the L6. Is it a "gen-u-INE" Nissan? Nope, but it does the job quite well. I am running one in my car without issue. You can clearly see when the thermostat opens and the car runs 160 to 170 degrees when cruising.

Edited June 22, 201014 yr by ktm

i was having similar issues. purchased 160 thermostat and temp sender from rock auto - gauge was reading high and put thermostat on the oven and it didn't open till 180+. purchased sensor and thermostat from the z-store - everything working great.

You guys sucked me into caring about another years old thread. Do wish you would stop doing that!!

My 72 gives me the creeps once in a while when the thermometer works like that, guess i have just get used to it... maybe too much.

An engine that's consistently running 15-20 degrees hot USUALLY has a pressure leak. Put a pressure tester on it. A single loose hose clamp / drip can be all it takes.

Get a meat thermometer. Put it in the top of the radiator. Start the car and let it idle until it gets full up to temperature. Check the temperature of the actual radiator fluid.

You will feel better. Trust me.

Mine also has the same problem. Temperature rises to 3/4 without the thermostat intalled.

Just to let you guys know, the problem with mine ended up being the thermostat temp sensor. The aftermarket one was reading high; once I installed a genuine Nissan one it has been reading at about half or under half.

Found a fix for 240Z Temp Gauges that always read past half, even after 3 row High Efficiency radiator, Nissan 170º T-stat, new Nissan temp sender.

Ok the middle of the gauge is approx 185º, always checked with thermometer in radiator and compare what the gauge in the car is reading, in my case I had 2 240Z's at my shop the both showed inaccurate readings at 185º as the gauge was past the M in TEMP.

Also check a 280Z with thermometer in radiator to verify its accuracy and its gauge was right on the money.

Anyway I installed a variable resistor between the water temp sending unit and the yellow feed wire from the gauge and adjusted it accordingly. . . . .Problem Solved.

 

Here are some pics

And yes I know this is a 10+ year old thread, but maybe it will help somebody out that's frustrated with constant high temp readings.

Joe

Operation Z

 

 

What were the specs on your variable resistor?

8 hours ago, operation z said:

Found a fix for 240Z Temp Gauges that always read past half, even after 3 row High Efficiency radiator, Nissan 170º T-stat, new Nissan temp sender.

Ok the middle of the gauge is approx 185º, always checked with thermometer in radiator and compare what the gauge in the car is reading, in my case I had 2 240Z's at my shop the both showed inaccurate readings at 185º as the gauge was past the M in TEMP.

Also check a 280Z with thermometer in radiator to verify its accuracy and its gauge was right on the money.

Anyway I installed a variable resistor between the water temp sending unit and the yellow feed wire from the gauge and adjusted it accordingly. . . . .Problem Solved.

 

Here are some pics

And yes I know this is a 10+ year old thread, but maybe it will help somebody out that's frustrated with constant high temp readings.

Joe

Operation Z