Not really the right place but someone might of come across problem before....

2.7 Nissan engine in my Hackney taxi. When "normal" town driving the temp reads about a quarter but when doing around 50 on a run the temp slowly rises and keeps going up!!.

Have tried new rad, temp switch, flushed out system, thermostat and its still same. Waterpump maybe?

Any ideas?

Cheers!!