Hi there,
My son and I own 4 Isuzu bighorns between 92 and 96 in age.
They all run great except one of them...and we can't figure out what's wrong with it.
It ran fine and didn't overheat until a couple of months ago.
It starts first time every time and runs very smoothly...but it starts overheating after about 15 mins of driving at the open road speed limit of 100kmph.
it doesn't heat up when idling, stopped at traffic lights or roadworks or going through our local mountain pass at 80kmph.
The temperature gauge sits bang in the middle between hot and cold until we sit at 100 on the open road.
it doesn't misfire or run roughly...we've run out of ideas on how to fix it.
We have put in a new cam belt, water pump, radiator and changed the viscous fan and checked all the hoses to no avail.
Not sure where to go to next. Surely if it was a head gasket blown we'd see oil in the water etc..but we don't and it doesn't leak any oil or water.
Can anyone please help us?
Cheers
Alexa and Jacob