thermostat question from a newbie.
02-25-2013, 09:21 PM
#16
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Location: Airdrie, Alberta
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I'm glad I'm not the only one that has observed this. I could understand and accept it if it only did it when I was towing or carrying a load, but driving along at 45 mph and seeing the gauge drop from a little over 190 to 140 freaks me out. I have bought a Cummins t-stat for the truck and will install it soon. When I replaced the oem stat with one from NAPA, is when I started to see the temp swinging. Prior to that, the truck always ran cold, and I thought the stat was stuck open. Thanks for all the replies.
As for the oil pressure issue, the question is where are you monitoring your oil pressure from? If it is off the oil filter head, that is the first place to get oil. The oil pressure sensor is off of the cam oil gallery, which is the last place to get oil. So the delay could be quite possible. If you're measuring it from the same place as the factory sensor, then you'd be seeing the lag of the electronics.
02-26-2013, 01:02 PM
#17
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Some folks are totally content with a 50+ degree temp fluctuation because "the manufacturer said..." while others see it as a problem and seek ways to fix it.
It didn't fluctuate up and down in time with the coolant gauge at all.
Indicated to me that the engine temperature was very consistent.
03-09-2013, 05:48 PM
#18
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The only way the oil will change temperature is through heat saturation. Same with the coolant obviously, but the coolant is routed around all the hottest parts of the head and in large quantities, so heat saturation happens very quickly. Not so with the oil - it's used to cool the pistons yes, but in relatively small quantities compared to what's in the crank case so heat saturation happens slowly in the oil, not to mention oil requires more heat energy to change it's temperature than coolant. So under normal operation, coolant temp can fluctuate up and down while oil temperature will stay relatively the same.
03-15-2013, 06:12 PM
#19
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I have observed the same fluctuation in the coolant temp for many years on both my 96s. Usually in unloaded form. Pulling or hauling tends to be more uniform in the coolant temp readings. Both are factory original thermostats still.
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