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Overheating - double checking steps


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I've experienced and overheating issue for the first time, and have read through the various posts on this topic - I just want to double check my understanding is correct before committing to further action. Any guidance will be welcome.


'54 plate 350z GT, always well serviced and I don't drive it hard. On a 20min urban journey the Mishimoto fans kicked in after just 5 mins (not running A/C) and the temp gauge rose to over the horizontal for the first time in my 3 years with the car. I put the heater fans on full blast in the cabin and they blew hot. I kept the car moving at low revs scooping in loads of cold air through the rad. The needle would rise further when in traffic but not into the red. I know the car and know this is not normal, especially given the outside air temp was in single figures.


Once stopped I checked the following:

1 - Top hose was very hot

2 - Bottom hose was cold at the rad end and warm next to the thermostat

3 - No coolant leaks

4 - Coolant reserve tank was about 1 inch above the top fill line


Once the car was cold I checked

1 - Coolant level was bang on top fill line (I check this and all fluids monthly anyway)

2 - Coolant had no sign of oil

3 - Oil had no sign of water (no cottage cheese)

4 - Rad top filler was full with coolant

5 - Fans do turn


I think my next steps therefore are.


1. Coolant bleed in case there is an air lock.

2. Thermostat replacement if the bleed has no affect.


Does that sound right or is there something else I should check before starting work?


Many thanks




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Assuming that the fans are working properly and the gauge is not giving you a false reading


If so, then definitely a blockage of sorts.


(1) Air in system: Bleed system.

(2) Flush out radiator, both ways.

(3) Remove and test thermostat.


Report back if these do not cure your over temperature issue.






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