Over heating
- Thread starter Moinoz
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There could be a few reasons for this, thankfully not all will cost you a lot of $$ to check.
1) Viscous hub (fan clutch) is faulty. Simple test: get the engine to normal temp, then pull over but don't turn off the engine. Pop the bonnet and while you're watching the fan, have someone turn the engine off. The fan should stop with the motor - it shouldn't spin on after the engine has stopped. If it has, the viscous hub either needs more oil or needs replacement.
2) Fan is faulty. Cracked blades can cause the fan to become less effective. Unfortunately it can also cause the blades to flex enough to come into contact with the radiator which will destroy it. Turn the fan over (cold engine is suggested, more so you don't burn yourself!) and inspect the blade roots.
3) Blocked radiator. Due to the way the filler is mounted, this isn't very easy to spot. It might be obvious under thermal imaging if you've got access to such a device (pest inspectors have these too, to check for termite activity, so if you have a friend in that business ...).
4) Faulty thermostat (unable to fully open). The thermostat is usually closed when the coolant is under temp and as the temp rises the thermostat opens allowing the coolant to flow. It might not be flowing enough to cope with highway driving. It needs to come out to be tested/checked.
5) Unfortunate placement of accessories. I've done this myself. I had two IPF square driving lights (like in my avatar picture) and added a light bar to the underside of the top of the bullbar. This restricted airflow enough so that if I was travelling at highway speeds the coolant temps would rise rapidly, and this was really noticeable going up hills.
Hope that helps.
There could be a few reasons for this, thankfully not all will cost you a lot of $$ to check.
1) Viscous hub (fan clutch) is faulty. Simple test: get the engine to normal temp, then pull over but don't turn off the engine. Pop the bonnet and while you're watching the fan, have someone turn the engine off. The fan should stop with the motor - it shouldn't spin on after the engine has stopped. If it has, the viscous hub either needs more oil or needs replacement.
2) Fan is faulty. Cracked blades can cause the fan to become less effective. Unfortunately it can also cause the blades to flex enough to come into contact with the radiator which will destroy it. Turn the fan over (cold engine is suggested, more so you don't burn yourself!) and inspect the blade roots.
3) Blocked radiator. Due to the way the filler is mounted, this isn't very easy to spot. It might be obvious under thermal imaging if you've got access to such a device (pest inspectors have these too, to check for termite activity, so if you have a friend in that business ...).
4) Faulty thermostat (unable to fully open). The thermostat is usually closed when the coolant is under temp and as the temp rises the thermostat opens allowing the coolant to flow. It might not be flowing enough to cope with highway driving. It needs to come out to be tested/checked.
5) Unfortunate placement of accessories. I've done this myself. I had two IPF square driving lights (like in my avatar picture) and added a light bar to the underside of the top of the bullbar. This restricted airflow enough so that if I was travelling at highway speeds the coolant temps would rise rapidly, and this was really noticeable going up hills.
Hope that helps.
Rhys123
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Interestingly I am in exactly the same situation.
Things I know
Its not the thermostat
Its not the radiator
Its not the fan
I don't believe it is the head in any way (well hopefully).
Has anyone had issues with the water pumps on these?
Cheers Steve
Things I know
Its not the thermostat
Its not the radiator
Its not the fan
I don't believe it is the head in any way (well hopefully).
Has anyone had issues with the water pumps on these?
Cheers Steve
Water pump life will depend on the coolant used, I've always used a minimum 33% coolant mix (see note below) in mine and never had a problem, but I'm supported by a water supply that never registers on a water-hardness test (really, we've tested it several times and it never shows, I guess that's an advantage of living a dozen or so km from the dam!).
There have been only a few reports (that I recall) of failing water pumps on this forum. It would be worth checking that the fan belt isn't slipping on the pulley, but also that there's no air trapped in the system - air will reduce the cooling system's effectiveness. If yours is an auto, you'll also have the transmission cooler inside the bottom of the radiator, which (if the tranny is hot - and I don't mean it looks good in leather and heels) will add to the radiator heat. You could probably diagnose the entire system with a thermal imager (and I'll be looking to do the same myself soon, just for curiosity's sake). This will indicate cold spots in the cores, pointing to blockages, as well as giving an indication of flow rates (blockages, pump, thermostat operation).
Note: ethylene glycol (the main ingredient in radiator coolant) isn't as good a conductor of heat as water is. However, it modifies the freezing and boiling temperature of water, so it's necessary to have - especially since our diesels like to sit in the low-to-mid 90s in celcius and happily pop over 100C when climbing hills. Nissan recommend a 50/50 mix which is fine, but a 33% mix (33% ethylene glycol, 67% water) allows for slightly better thermal transfer. It's not a world-shaker, my choice to do it is purely because the local mechanic who does my servicing uses that mix for all the trucks, utes, tractors and cars that they service in the area, they've done a superb job for me in the past and so I trust their call on it.
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