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4965 messages, Last post on Dec 04, 2009 at 9:52 PM

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#4788 of 4965 Cooling fans run for no reason. by cricketcan Apr 15, 2009 (4:19 am)
2000/Buick/Century/3.1lt engine/Automatic trans/145,000 miles My cooling fans come on for no reason. The engine is cold and the the fans will come on and run the battery down. I've check the resistance on the cooling sensor. It was about 40 degrees outside and the ohms of res. was about 2500, about 140 degree's after running the engine for 10 to 15 minutes, it was 600 to 650 ohms. That is about right (Right)!!!! I pulled the plug to both fans and I have have 12.5 volts on the light blue wire on that harness. Is that part of the AC system. I can't find ant wire on the high side of the drier that is that color. Replies to this message: kiawah (Apr 15, 2009 4:43 am) cricketcan (Apr 15, 2009 5:42 am) obyone (Apr 17, 2009 12:10 pm)
#4789 of 4965 Re: Cooling fans run for no reason. [cricketcan] by kiawah Apr 15, 2009 (4:43 am)
Replying to: cricketcan (Apr 15, 2009 4:19 am) I can't speak to the specifics of your vehicle, I don't have the electrical schematics. The cooling circuitry for most vehicles has three parts, the control circuitry that determines when to turn on, a set of relays or even an integrated circuit, and the fan motors themselves. Your fan motors are turning, so they obviously have power and the motors aren't 'frozen' so those appear okay from your description. The relays are to there, because of the high current draw of the fan motors. Their contacts(points) are capable of handling the higher current draw and arching that can occur when you turn motors on and off. Usually when a relay is bad, it either never turns the fan on, or the fans are always on and never turn off. It is not abnormal for a relay to go bad. I'm not exactly sure of your symptom, because you say they "come on for no reason". If 'come on for no reason' means that they are off, and then they turn on, then your relay is probably okay. If 'come on for no reason' means that the fans are always running (or always running when the ignition is in ON position), then I would suspect the relays. If your fans are sometimes off and sometimes on, then I suspect that the relays might be okay. They are switching back and forth between on and off. You don't know for sure until you meter them out. But the typical relay failure is either 'never turns on', or 'never turns off'. For the control circuitry, in older vehicles it used to be that the thermostat controlled the relay. Then they wired in circuitry that when the A/C was turned on, it also turned on the relays to the fans no matter what the temperature. In newer cars the control circuitry is typically the engine computer, monitoring vehicle speed, a/c load, electrical voltage, engine rpm, engine temperature, ambient air temperatures, etc. If your relays aren't your problem, then you will need to get a set of electrical schematics for your vehicle which detail out what are the 'inputs' to the computer that are being monitored to turn on the relay and fans. You could have one of the 'inputs' bad (always calling for the relay/fans to be on), or your computer itself could be bad (misinterpretting the inputs, and turning the relay/fans on when not needed). Good luck. Replies to this message: cricketcan (Apr 15, 2009 5:42 am) obyone (Apr 17, 2009 12:10 pm)
#4790 of 4965 Re: Cooling fans run for no reason. [kiawah] by cricketcan Apr 15, 2009 (5:42 am)
Replying to: kiawah (Apr 15, 2009 4:43 am) The part about the PMC could be true. One night I went out and the fans where running for no apparent reason. I couldn't get them to shut off and it was late so I unplugged them. Later the next day I went out to check them out and plugged the fans back to the harness and they didn't start runnning again. Strange!! Started the car and took it around the back of the house to the garage to diagnois and shut the car off. they were running again. Engine still cold. Only ran 3 min. tops. With the ign key in the off position Thought of the defrosters and shut everything down inside the car, fans still running with key in off position. Hoping cost of fix was not PMC. Thanks Replies to this message: obyone (Apr 17, 2009 12:10 pm)
#4791 of 4965 Re: Cooling fans run for no reason. [cricketcan] by obyone Apr 17, 2009 (12:10 pm)
Replying to: cricketcan (Apr 15, 2009 5:42 am) GM has a service bulletin addressing this issue. It first appeared on the then newly designed Regal back in 1997. You would think that four years after its introduction they would've worked the redesign into the newer models. Then again the more I think about it GM had an intermediate steering shaft issue with their GMT 800 trucks that took 8 years to resolve. If you haven't found the solution by now, post here and I'll try and look up the final resolution.
#4792 of 4965 Pinging by cptlocksley Apr 19, 2009 (6:50 am)
I have a 92 ford ranger with the 4.0l that makes a pinging noise under load. What are the possible problems? I have heard that is normal for that engine but I would like to fix it anyway. Replies to this message: Mr_Shiftright (Apr 19, 2009 7:27 am) cptlocksley (Apr 19, 2009 7:58 am) kiawah (Apr 19, 2009 8:26 am) Mr_Shiftright (Apr 19, 2009 8:56 am) bolivar (Apr 19, 2009 10:52 pm)
#4793 of 4965 Re: Pinging [cptlocksley] by Mr_Shiftright HOST Apr 19, 2009 (7:27 am)
Replying to: cptlocksley (Apr 19, 2009 6:50 am) Pinging under load is not good. What you are hearing is, literally, the internal parts of your engine rattling around, and, possibly, the walls of your cylinder actually flexing. You can burn a hole right through a piston from pinging. HOWEVER, there is "pinging" and there is PINGING. A very slight, short burst of this noise under heavy load in a high gear might be pretty normal, but if you are climbing a hill and the ping just keeps on going (in other words, not a short, temporary burst) you are headed for disaster. Cause? Various. Most common: 1. Fuel octane too low 2. Timing too advanced 3. Heavy carbonization of cylinder head or tops of pistons 4. Defective distributor/advance mechanism (depends on the car). Replies to this message: cptlocksley (Apr 19, 2009 7:58 am) kiawah (Apr 19, 2009 8:26 am) Mr_Shiftright (Apr 19, 2009 8:56 am)
#4794 of 4965 Re: Pinging [Mr_Shiftright] by cptlocksley Apr 19, 2009 (7:58 am)
Replying to: Mr_Shiftright (Apr 19, 2009 7:27 am) I was told i would have to pull the heads and clean up the top half of the engine. Knowing the some of the past history of the truck, it has not had the best service intervals. Just thought that I would ask before spending the time to tear it down and rebuild it. Thanks for the reply. Replies to this message: kiawah (Apr 19, 2009 8:26 am) Mr_Shiftright (Apr 19, 2009 8:56 am)
#4795 of 4965 Re: Pinging [cptlocksley] by kiawah Apr 19, 2009 (8:26 am)
Replying to: cptlocksley (Apr 19, 2009 7:58 am) Try to isolate the cause a little, for instance.....check the timing and timing advance, and put in a tankful of higher octane....before you start tearing the engine down.
#4796 of 4965 Re: Pinging [cptlocksley] by Mr_Shiftright HOST Apr 19, 2009 (8:56 am)
Replying to: cptlocksley (Apr 19, 2009 7:58 am) That's a pretty drastic solution---you should definitely check the timing mechanisms and also throw in some premium gas and see how that helps.
#4797 of 4965 Re: Pinging [cptlocksley] by bolivar Apr 19, 2009 (10:52 pm)
Replying to: cptlocksley (Apr 19, 2009 6:50 am) The 3 Liter motors almost all ping. Not much to do about it but use higher octane fuel. When a 4 Liter pings, it means the bolts holding the intake down have loosen up. This allow air to be pulled into the intake, leans out the mixture, and this causes ping. Start in the center and criss-cross tightening up the intake manifold bolts. I think they are about 9mm or so. A 1/4 inch drive with flex connector and extensions of various lengths will also be needed. I don't know the torque needed. Just snug them up, you are going to find several that are loose. This happened on my 94. I bet it's your problem. Otherwise, 4 Liter Rangers do not ping.