Quote:
Originally Posted by carpoor
Two things... thermostat? What temperature is it? Could it be stuck open or closed? And, what condition are the hoses in? They might collapse when it gets hot.
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Grab a hold of the fan blades, engine off of course and try to spin the fan, should spin but should have resistance. Also try to move a blade front to back, look for worn out bearings in the clutch assembly. Open the hood when the engine is cold. Start it up and you should hear the fan 'roar' for a second or two. If it's engaging properly when the engine gets hot you should also be able to hear a change in the amount of noise from the fan. Let the engine idle and get hot, should hear when the clutch engages.
If it spins easily by hand or you don't hear it engage it needs to be replaced. Hayden 2747 HD clutch is the best choice.
What type of fan? Is it a stock 7 blade fan? Carpoor brought up a good point. The lower hose can collapse when hot if it doesn't have a spring inside to keep it in shape. If the the thermostat was stuck closed the engine temp should continue to climb from the time you start it until it's way overheated. That doesn't mean the thermostat couldn't be bad, not opening and closing as it should. Stuck open, that won't cause a problem, except the engine might never come up to temp. It's a myth that stuck open or no thermostat doesn't allow the coolant to stay in the engine long enough to cool it. It just doesn't work that way. The more cool water you can force through the engine the more it will cool. They make high volume water pumps for engines that have a cooling problem, more cool water, lower temps.