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AH64ID
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The 3rd gen 6. 7's use a 190° thermostat that opens at 190± 3°, and goes full open at 207°, with a max allowed temp of 225°. The 4th gen bumped the thermostat to a 200° thermostat, and I can't find the specs on it, but if it's anything like any other Cummins thermostat it will crack at 200°± 3°, and be full open at about 217°, with a max allowed temp of 235°.
So what is the original truck pulling for temp?
I have also heard that a deleted truck that pulls hard may move the coolant to fast thru the radiator because the 6. 7 H20 pump is designed to flow thru the EGR cooler and when you pull the EGR cooler the H20 pump is too big. A 5. 9 H20 pump is not an uncommon swap, but I am not sure if it will fix his issue.
With the large temp swing from crack to full open a large temp swing is normal. On a 190° thermostat it's normal to be at about 180° at idle, cruise at 190°-194°, around town at 193°-195°, and towing at 193°-215°. The OEM gauge doesn't show much as much movement but watching it on a OBDII reader tells the whole story.
So what is the original truck pulling for temp?
I have also heard that a deleted truck that pulls hard may move the coolant to fast thru the radiator because the 6. 7 H20 pump is designed to flow thru the EGR cooler and when you pull the EGR cooler the H20 pump is too big. A 5. 9 H20 pump is not an uncommon swap, but I am not sure if it will fix his issue.
With the large temp swing from crack to full open a large temp swing is normal. On a 190° thermostat it's normal to be at about 180° at idle, cruise at 190°-194°, around town at 193°-195°, and towing at 193°-215°. The OEM gauge doesn't show much as much movement but watching it on a OBDII reader tells the whole story.
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