coolant temperture

mrM

Club Member
at idle my z31 water temp gauge goes up to nearly 3/4 before the radiator fan comes on,i would of thought it should be coming on earlier than that like half way or very slightly over?,the engine doesnt boil but gets very hot,ive changed the coolant,thermostat,rad hoses and rad as part of the restoration im doing on the car,also the binnicle clocks including temp gauge were changed,but its always gone to nearly 3/4 before the fan comes on even before replacing those parts,im just wondering at what point other peoples z31 fan comes on? thanks
 

Jimbo

1978 260z in yellow
Club Member
have you tried taking the sensor out and cleaning behind it?
quite often the sensor gets a buildup of crud behind it so it takes ages for the hot coolant to reach the temp sender and make it switch the fans on.
other than that can you try another sensor
 

mrM

Club Member
i put a brand new rad on so know the sensor in the rad is clean,but maybe its not working 100%,i ll give changing it a go and see what happens ;)
 

Mr.F

Inactive
Z31 has two sensors in the radiator for stage 1 (1400rpm) and stage 2 (2000rpm) fan operation (and second fan on A/C equipped cars). Perhaps only sensor 2 is working?

Sensor 1 switches at 90 degrees C and sensor 2 at 100 degrees C.
 

mrM

Club Member
i havent got the second stage 100 degree switch fitted just the 90 degree one because z31 radiators are no longer made and unavailable/impossible to find new in the uk,im using a usa one which only has one switch hole.....,i have put a second fan in the shroud,my car doesnt have ac but it looks like the wiring connections for it are already there to wire it up as it plugged straight in to a connection there by the single fan connection......would this second fan normally only work on the second stage?......think i ll try and make a adaptor to fit both switches and replace the suspect 90 while im at it
 

mrM

Club Member
i marked the one that was in the 90 hole before taking it out of the old rad and fitting it in the new one also the 90 one has the plug in connection attached to it nearest to it,while the 100 is further away so it should be correct,hopefully i ll be able to change it out at weekend and solve the problem then try and find a 100 switch that goes in the smaller drain plug hole if its possible once i know what thread it is
 

mrM

Club Member
well ive tried 4 90 switches i had around and its still the same at present,the switches ive tried are 90 for sure,i checked the wiring diagram colours,ive also had a funny problem with the interior fan heater in that sometimes it stops working then starts back up again,and also at different times ive warmed it to normal temperture it blows hot,luke warm or hot.......all on the hot setting with the interior fan on full.....everything is new on the cooling system including a low temp thermostat......i cant remember for sure but its something like a 68 degree or 65 degree.....at the time i thought it would run a bit cooler with this...standard one according to the book is 76.5 degrees...thoughts?
 

mrM

Club Member
edit..........and also at different times ive warmed it to normal temperture it blows hot,luke warm or COLD!.......all on the hot setting with the interior fan on full
 
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