Thread: Cooling system strangeness

Yes, I had the same thing. Temp gauge stayed down, changed thermostat, all good for about three years then low temps again. I cleaned the connection on the temp sensor, all good again.

The engine harness where it runs around the front of the head shorting to ground will cause the temp gauge to drop also.

Check the fuel temperature input too with nanocom, it shoud be a bit lower than the coolant temp so if the FT is higher the problem is with your coolant temp sensor or circuit

Originally Posted by sierrafery

Check the fuel temperature input too with nanocom, it shoud be a bit lower than the coolant temp so if the FT is higher the problem is with your coolant temp sensor or circuit

Thanks mate. Fuel temp is around the same or a bit lower. The temp gauge does get up to normal when it’s working hard and sinks down again when the hard work is done. Nanocom reports temp as about 70 when the gauge rises and about 68 when the gauge goes back down. I’m leaning towards thermostat stuck open.

Yes, in this case seems very like open thermostat cos the gauge is normally acting like that... it goes to the middle at 70*C then up to the red at 120*C ...so quite useless as if you dont have an additional gauge to show you the real temp you can drive it at 115*C for long without knowing it which is not a good move.

Originally Posted by Markf

Thanks mate. Fuel temp is around the same or a bit lower. The temp gauge does get up to normal when it’s working hard and sinks down again when the hard work is done. Nanocom reports temp as about 70 when the gauge rises and about 68 when the gauge goes back down. I’m leaning towards thermostat stuck open.

For mine it is unlikely that the temp that low is caused by the thermostat, I would be looking at the coolant sensor on the block and having just changed one out which started giving lower readings intermittently and having the red light on and off with temp gauge up and down. The two new sensors I got by the way give different readings which may back up something I read a while ago as to sensors and using a OEM spec one for the TD5

Having an electric waterpump and NO Thermostat, the behavior you are describing does not mirror my findings of what the open system does. I did reset the pump Controller higher to get less EWP action on start up and get the temps up. Firstly the warm up is a lot longer which would be the first indicator if a thermostat was bung, but the temps at 100kph on a cruise are still around 80-85C and will rise to the low 90C's and unless your VF is locked on, would imagine that this will be the case.

Originally Posted by RRT

For mine it is unlikely that the temp that low is caused by the thermostat, I would be looking at the coolant sensor on the block and having just changed one out which started giving lower readings intermittently and having the red light on and off with temp gauge up and down. The two new sensors I got by the way give different readings which may back up something I read a while ago as to sensors and using a OEM spec one for the TD5

Having an electric waterpump and NO Thermostat, the behavior you are describing does not mirror my findings of what the open system does. I did reset the pump Controller higher to get less EWP action on start up and get the temps up. Firstly the warm up is a lot longer which would be the first indicator if a thermostat was bung, but the temps at 100kph on a cruise are still around 80-85C and will rise to the low 90C's and unless your VF is locked on, would imagine that this will be the case.

Warm up takes forever and on a flat cruise at 100kph it only gets up to about 65 or so with ambient being about 5 or 8. Going uphill in 3rd locked up it can get as high as 72 but as soon as the hill is crested it goes straight back down. The times that I've looked at the fuel temp it seems to vary between about 45 and 50 which indicates to me that the whole cooling system is cold. The thermostat's coming out later today. When I get it out (and the new one in) I'll put it in the fridge and see what's what.

Try to stop the viscous fan with a rolled up newspaper when the engine is cold...if you can't it's another issue which brings the temp down even more so you need a new one as well