Diagnostic Corner: How to Tell That It’s Time to Replace your Cooling Fan


Things are going great –


You’ve just left the ballgame, the home team won, and it’s time to head back to the house to enjoy some post-game grilling.  Though the traffic leaving the stadium is a bit frustrating, it isn’t too bad, as few things can dampen your spirits on this particular Sunday afternoon.


Until you notice the engine’s temperature gauge beginning to rise…


Is your thermostat shot?  Does your radiator have a leak?  Is the cooling fan assembly malfunctioning?  You’d better act quickly if you want to save your engine!


How Important is your Vehicle’s Cooling System?


Let’s get one thing straight….it means EVERYTHING.


Diagnostic Corner Cooling Fan


Overheating can spell DOOM for your engine.  In fact, when it comes to your vehicle, and the obvious hope that it lasts for quite some time, an overheating engine is the #1 cause for engine overhauls and replacements.  And, unless you have a relatively new vehicle, many will elect to “junk” a vehicle that has a bad engine.


But, not all is lost!  After all, in our scenario above, we have just noticed that the engine is overheating.  Chasing a cooling system problem can be difficult, but when you know how the system functions, and what warning signs lead to which components, you can quickly identify and resolve the issue at hand.


Diagnosing a Failing Cooling Fan Assembly


The cooling fan usually mounts directly to the radiator, providing the necessary air flow to cool the coolant, helping to keep your engine at a safe operating temperature.  Without this airflow, the system cannot function as it should.


Singling out the cooling fan as the culprit requires a few observations:


(1)    Does the engine temperature rise when stopped, but drop when in motion?


When moving, air flow isn’t a problem.  With air passing through the radiator, the coolant can cool.  However, when stopped, the temperature rises because the cooling fan isn’t supplying the necessary air flow.  Make sense?  This is a telltale sign that your cooling fan is hanging your engine out to dry.


(2)    Is There Coolant in the Radiator/Reservoir?


This sounds elementary, but in truth, it happens more often than one would think!  Rarely do vehicle owners check their coolant, and the result is often a low coolant level and the subsequent overheating issues.


NOTE:  DO NOT, under any circumstance, open the radiator cap to check the coolant when the car is hot.  I have made this mistake before, and I used every curse word under the sun to explain the error of my ways.


(3)    How Does the Cooling Fan LOOK?


Again, it seems like we’re talking about something that should be apparent, but there may be corrosion, broken blades, or simply a motor that is falling apart when you check out the cooling fan assembly.  Also, it’s a good idea to wiggle the wiring connections a bit.  Sometimes, a wiring harness can loosen over time, rendering the fan useless.


Check your wiring connections, and you may save yourself some money!


Repair Prognosis


Cooling fan repairs are actually quite easy for most vehicles.  Because the entire assembly mounts to the back of the radiator, there are usually just a few mounting bolts and a couple of wiring connections.  For some vehicles the area may be a bit cramped, but if you use a catch pan, you can easily drain the radiator, disconnect the upper radiator hose, and create plenty of room to work!


Once the new assembly is installed, connect the cooling fan motor wiring harnesses, and Voila! – You’re all set.


NOTE:  Be careful when mounting the cooling fan assembly.  You are bolting directly into the radiator, and over tightening can damage the radiator housing!  This leads to leaks, which leads to more overheating, which leads to more repairs!


…which leads to more frustration, which leads to…nevermind, you get the idea…



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