Hello, I'm hoping for input on a problem I'm having with a 2004 LS 3.9. The problem is that the cooling fans turn on high and never shut off(until I turn the engine off). In the research I've done, there's only the CHT sensor. Is that correct? I ask because when I'm looking at my scanner I can read the CHT sensor reading and two other coolant temp readings. The fans will kick on when the coolant temp readings hit +110*C(about 235*F) but the CHT is reading 25*C(77*F). The thermostat was replaced last summer. The temps here in Chicago have been pretty frigid and the fan will still turn on high until I shut off the engine. The CHT readings will eventually match up with the other coolant tamp readings. They're usually 1-2 degrees from each other. I tried the 19 step procedure in burping the cooling system. Car idled for an hour before the fans turned on high and stayed there. Even after the radiator cooled off(I can reach the lower radiator hose and it was cold again). Once the engine is off the after-run pump turns on and the coolant bottled is gurgling. I read somewhere that that happens because of air in the system. Didn't sound right so I turn to you in hopes of better direction. I was wondering if these water pump impellers are known to come loose or break. Maybe not flowing enough once engine is hot? Any help is greatly appreciated, thanks!
Cooling Fan Problem
- Thread starter 427sierra
- Start date
tixer
Lincoln Evangelist
Welcome, Sierra!
Although I'm hardly an expert on the LS, don't forget that with most any car the A/C compressor will engage with the "defrost" setting, which will in turn engage the fan. You'll want to be sure that you do your testing with the climate control as "off" as you can get it.
1-2 degree differences for electronic temperature sensors seems to be the norm wherever I encounter them. I don't think I'd sweat that too much.
Although I'm hardly an expert on the LS, don't forget that with most any car the A/C compressor will engage with the "defrost" setting, which will in turn engage the fan. You'll want to be sure that you do your testing with the climate control as "off" as you can get it.
1-2 degree differences for electronic temperature sensors seems to be the norm wherever I encounter them. I don't think I'd sweat that too much.
Yeah, it doesn't matter if the climate control system is on or off. With the temps we've had around here, the fans should never reach high speed. I've worked on volkswagens a lot and they have plastic impellers on their water pumps that break loose completely or once coolant gets hot. Was wondering if that may be an issue with these. Car doesn't overheat but does reach 240*. Shouldn't they be right around 220*?
Thanks for your input!
Thanks for your input!