To DXJ
HI,
The fan should be "loose" ie driven slowly by the engine when cold. And it should be "tight" ie spun hard & fast by the engine when hot.
The idea is to suck maximum air as the temp rises.
Just a thought, if you say temp goes up when idling, maybe your water pump impeller is corroded or bad. Maybe just not enough water flow when idling. Very unusual that the fan isn't drawing enough air to cool an idling motor, not many engines overheat when idling but run okay when driving due to blocked or too small radiator.
I would be checking a few simple things first before laying out the cash.
I don't have a 4L engine but remember reading on US lists about reverse rotation water pumps on certain models of 4L. Wrong one fitted to wrong motor I think did as you describe. Has the pump ever been replaced?
Maybe the serpentine belt is wrapped the wrong way?
Lastly, I have had that sort of problem when there is a pocket of air trapped in the engine. Only when water pump has some speed up does it force the water fast enough to get by the big bubble of trapped air. At idle the bubble accumulates at the top of the engine and effectively stops water circulation. Maybe just "crack loose" some of the hoses when pressurised, just behind the thermostat etc to bleed out any air.
These days most cars have air bleed lines ( eg XJ diesel has two ) or screws ( eg Commodore V6 ) to bleed out air.
Remember, after filling the radiator most people forget to bleed air out of the heater.
This happens every time coolant is touched on my Holden as no one ever bleeds the water lines to the LPG converter. Dealer gave me blank looks when I complained of 1.5L coolant needed to be added after they serviced it.
Good Luck
|
