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dgerb 08-08-2005, 10:47 PM Sorry if this has been discussed before, but I've noticed that the fan on my 04 LLY is engaged when cold (just leaving garage). It's very noisy and stays on for about 3-5 minutes or so. Is this "normal" if so, can anyone explain why this is so...... killerbee 08-08-2005, 10:55 PM search for the term "morning sickness" It is considered "normal", in reality it is a design flaw. LyleP 08-08-2005, 10:55 PM Hi dgerb, Perfectly normal. You'll find a good discussion here --> http://dieselplace.com/forum/showthread.php?t=36345 ccdguy 08-08-2005, 11:14 PM Normal... I guess..... mine does it sometimes, and then other times it doesn't. I don't do anything different each time so who really knows why. Oh and I keep it in a garage thats heated and cooled so the temp is the same, and so that shouldn't be a factor. TxChristopher 08-08-2005, 11:50 PM It happens because the fan lockup is controlled by a bi-metallic spring that opens an orfice and allows viscous fluid to enter the "drive" compartment of the fan "clutch". The reason it runs in the morning is because it sat there after you killed it and the heat underhood rose once you killed the engine, enough so that the spring was moved open (just like a thermostat) and the fluid ran into the drive section. Once you get going in the morning the temp at the fan face is low because it cooled overnight and the orfice is closed and the fluid is pumped via centrifugal force back into its home and the fan goes away. . BullydogPowered 08-09-2005, 11:42 AM good explanation.... i wondered why it was like that. i hate it when it runs, sounds like the truck is going to blow up but goes away after a few stop lights | ||