Cooling fan help!!

66coupe

66coupe

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I have a 02 LS sport with the v8. I'm having a problem with my cooling fan, It seems to come on and stay on all the time, Also the fan is really loud! Any ideas on what could be wrong? The car has 95k on it if it matters? Thanks in advance!
 
Much of what ive seen says to try replacing the thermostat.
 
66coupe said:
I have a 02 LS sport with the v8. I'm having a problem with my cooling fan, It seems to come on and stay on all the time, Also the fan is really loud! Any ideas on what could be wrong? The car has 95k on it if it matters? Thanks in advance!
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Usually, this is a sign that the cooling system isn't working very well, and usually that is because there is air in the system. You're lucky having a gen I in this case. It is probably only the degas tank that needs to be replaced. After that, bleed the air out using the procedure in the tech articles section.
 
Need to see if the engine is actually overheating. If so, then the computer is correctly engaging the fan.
If not, then the hydraulic circuit for the fan is borked. Likely the solenoid on the pump in that case.

The fan is loud cuz it's a good one. :)
 
well acording to the gauge it's not over heating. I just tore into it tonight and going to replace the heater control valve, all the hoses, the t-stat, and the degas tank. Also changing the belt and all the pulleys. Hope fully that takes care of the problem.

I'm also debating about changing the solenoid if I can find the info on it tonight.
 
ah-ha, right, different threads.
Yeah, might be the solenoid.

Use an OBDII reader to get the real temp. Computer commands full speed at ~230 deg or a/c on, but it'll ramp up to that starting at about 210 deg. You can also unplug the solenoid and measure resistance from brown wire to ground. 7.5k = cold. <=1k = hot (full speed). It's tough to get an accurate measurement, though. I tried using a IR thermometer to get similar readings but had mixed luck. The best spot to sense is the heads under the intake - tough to get a good reading. Anything else you can probe will be 10 to 40 deg cooler.

Sometimes just doing a fluid exchange can help. Pretty easy on the fan circuit - just pull the return hose, direct to a pan, plug the return on the bottle. Fire up the car, keep pouring in Mercon ATF (not Mercon V, just the regular stuff) until what comes out is red. I used two quarts or so. Happens real fast, so have some help running the car.
If you open the circuit during your work, you might need to use a vacuum pump to get it to work again.
 
Who has experience changing that hydraulic cooling fan pump? I'm in the middle of trying and can not get the 20mm wrench on it good enough to break loose the high pressure line. And what size is that tiny hold down screw on that line?
 
It leaks. That's why I'm replacing it. Fan works fine as long as I top off the reservoir daily.
 
It's just Really Really Hard and you may have to Break Stuff to do it. I had to cut the hose and still had to grind off a bolt head.
The bracket bolt should be a 7 or 8 mm.
 
joegr said:
Usually, this is a sign that the cooling system isn't working very well, and usually that is because there is air in the system. You're lucky having a gen I in this case. It is probably only the degas tank that needs to be replaced. After that, bleed the air out using the procedure in the tech articles section.
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Joegr (or whoever can help),

I'm having the same problem as the original poster. I recently had my coolant temp. sensor replaced and since I got it back from the shop, the fan is always on high speed, although the speed seems to be dependant on the RPM's of the vehicle. Any thoughts as to what the problem could be.

If it helps, the fan was RPM dependant before the sensor was replaced, although the fan only cut on when th A/C was on. I've recently (2-3 months ago) changed most of the cooling system parts (thermostat, Upper and Lower Rad. hose, engine fill tower and cap, Degas bottle(around 1 year ago) and degas bottle cap).

I searched and some have suggested that it could be the fan pump actuator. Is this true? Any help is appreciated. Thanks.
 
lbooth77 said:
I recently had my coolant temp. sensor replaced and since I got it back from the shop, the fan is always on high speed, although the speed seems to be dependant on the RPM's of the vehicle.
....
I searched and some have suggested that it could be the fan pump actuator. Is this true? Any help is appreciated. Thanks.
Click to expand...

Why was the CHT replaced?

The actuator normally fails such that the fan *never* speeds up, likely due to getting clogged.

The speed control for the hydraulic fan is pretty simple:
1) computer determines how fast it wants the fan (a/c on/off? CHT? speed? etc)
2) computer adjusts the PWM signal to the actuator
3) actuator modulates hydraulic line pressure

So if the pump and fan are working correctly (and having a fast spinning fan means they are), then it's either computer/sensors, cabling, or the actuator.

From looking at my old thread - http://www.lincolnvscadillac.com/showthread.php?t=70387 - I think the actuator is normally open (full fan speed) and the PCM pulses it closed to regulate pressure.
So, either the actuator's solenoid coil has gone kaput, or it's not getting the signal.

First thing's first - is the actuator plugged in, and does it look like the cable isn't cut?
 
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