Fast Fans

[sexyLS]

Hey guys,
Before I began, I searched for this answer and got useful information, but still didn’t get a clear answer.
A few months ago I had a coolant leak in the coolant outlet pipe. The car required coolant every two or three days. I had it replaced and all is well, but now I notice that my cooling fans stay on high once reaching operating temp. From what I understand, the cooling fans are to come on, when the coolant temp reaches a certain temp, and go off once cooled below that temp. My problem is that they stay on high once the temp is reached. They go off usually when I turn off the ignition. I read from other owners of similar problems, but some have never found a solution, others named the coolant temp sensor, some say the hydraulic fan, or a host of other parts. My question is what is the most common thing that would cause this and what should I check first?

 

[LS4me]

First off there is only ONE fan.

Next salient requirement; engine and year.

 

[JoshMcMadMac]

You may be running hotter than you think. The gauge does not directly reflect temperature. I have the same issue, and have found with a scanner that the coolant is actually closer to 240° even though the gauge is in the same place it always is. It might be as simple as properly bleeding the system:
http://www.lincolnvscadillac.com/tech/Lincoln-LS/CoolingSystemDraining/

 

[sexyLS]

Sorry the car is an 04LS V8

 

[joegr]

... others named the coolant temp sensor, some say the hydraulic fan, or a host of other parts. My question is what is the most common thing that would cause this and what should I check first?

I think that the coolant temperature sensor is unlikely to be your problem. I don't recall hearing of one failing. (I have heard of some wiring shorts to the head temperature sensor.)

Your one and only engine cooling fan is electric, not hydraulic. If your fan does not always go off when you turn the key off, your fan has a problem. If it ever comes on with the key on but the engine off, your PCM or the wiring from the PCM to the fan has a problem.

Odds are good that your engine actually is running too hot due to some cooling system fault. Just the be clear, exactly which parts did you replace?

 

[crosshair]

@ joegr..i sent you a pm...

 

[sexyLS]

I think that the coolant temperature sensor is unlikely to be your problem. I don't recall hearing of one failing. (I have heard of some wiring shorts to the head temperature sensor.)

Your one and only engine cooling fan is electric, not hydraulic. If your fan does not always go off when you turn the key off, your fan has a problem. If it ever comes on with the key on but the engine off, your PCM or the wiring from the PCM to the fan has a problem.

Odds are good that your engine actually is running too hot due to some cooling system fault. Just the be clear, exactly which parts did you replace?

I have replaced the coolant outlet pipe and I have put some water wetter in the degas bottle.

 

[joegr]

I have replaced the coolant outlet pipe and I have put some water wetter in the degas bottle.

There are three plastic parts at the front, and they get called different things.
Between the top of the engine, just over the water pump, is a short pipe that comes out at about a 45 degree angle and goes to the back of the pipe that crosses between the two cylinder banks. You have to remove or loosen the intake manifold to change this pipe (or cut off the rear bolts).
In front of this pipe is the biggest part of the three. It connects to the two cylinder banks, the 45 degree pipe, and the thermostat housing.
The front most is the thermostat housing. It has the thermostat and connects to the radiator hose and the heater hose.

Whichever two of the three that you did not replace, almost certainly need to be replaced and are probably the problem. There is also a 99% + chance that you need to replace the degas bottle.

 

[scjmc]

I can tell you from experience that joegr is correct. If the engine is running hotter than the set temp the fan will run at high. This begins while the temp gauge still reads at the midway point. You almost certainly have some air in your cooling system. These cars are very critical of any air in the cooling system. As joegr also stated once one of the plastic parts fail the others will fail at nearly the same time. Having had two of these cars I have had this happen twice myself.

 

[sexyLS]

I replaced the coolant outlet pipe as shown here. I had the degas bottle tested and it was fine. What else do I need to replace?

http://deneau.info/ls/s6x~us~en~file=s6x33010.htm~gen~ref.htm

 

[joegr]

I replaced the coolant outlet pipe as shown here. I had the degas bottle tested and it was fine. What else do I need to replace?

http://deneau.info/ls/s6x~us~en~file=s6x33010.htm~gen~ref.htm

Let me repeat.

1. Between the top of the engine, just over the water pump, is a short pipe that comes out at about a 45 degree angle and goes to the back of the pipe that crosses between the two cylinder banks. You have to remove or loosen the intake manifold to change this pipe (or cut off the rear bolts).

2. The front most is the thermostat housing. It has the thermostat and connects to the radiator hose and the heater hose.

Of course, all the related seals need to be replaced too.

I wouldn't trust any test of the degas bottle. The way they crack, they can get to where they only leak at exactly the right pressure and temperature. Also, sometimes they don't leak coolant out, but let air in. Did you test in under a slight vacuum to see if it would hold? What about the metal tube inside the bottle? If it gets loose at all, it lets air back into the engine. This too won't show up on any leak test.