oifla
Junior Member
Hello all,
Troubleshooting my 2004 with the 5.9L HO Cummins motor, 6 speed and 2wd. Only 190K miles.
Truck runs great, makes power as it always has, oil and coolant are good and healthy.
Issue I'm having is slightly higher than normal temps while driving on the highway. I'm running a fairly recent water pump, newish hoses, new radiator cap, and the cooling system doesn't use any coolant. Truck has a 190 thermostat.
Climbing hills around town and at highway speed especially the coolant temp climbs to 200-202 which is weird because the temp would always hold steady at just shy of the 200 mark on the dash but now it moves around a little over the 200 mark (verified by my obd2 scanner).
After highway driving, truck brings temp down at idle speed without issue and it idles at 190.
I've done a paper test on the radiator (meaning will it hold the paper up against the condenser/radiator) and at idle the fan rotates but doesn't hold the paper up. With the A/C on at idle, it holds the paper and the fan gets louder (so it must be somewhat getting more locked) but the temps go up. At higher engine speed like 2,000 RPM (while sitting in driveway) the clutch fan doesn't seem to be locking up and the temp starts climbing to 200-202. Only other symptom is that the upper hose seems to be pressurized (or more than I remember it being anyway).
I'd guess the issue is the fan clutch is letting go (seems to be original) but also I hesitate on throwing parts at it when (a) the highway speed temp shouldn't be affected by the fan clutch (b) it does seem to be somewhat working when the A/C comes on.
Thoughts?
O.
Troubleshooting my 2004 with the 5.9L HO Cummins motor, 6 speed and 2wd. Only 190K miles.
Truck runs great, makes power as it always has, oil and coolant are good and healthy.
Issue I'm having is slightly higher than normal temps while driving on the highway. I'm running a fairly recent water pump, newish hoses, new radiator cap, and the cooling system doesn't use any coolant. Truck has a 190 thermostat.
Climbing hills around town and at highway speed especially the coolant temp climbs to 200-202 which is weird because the temp would always hold steady at just shy of the 200 mark on the dash but now it moves around a little over the 200 mark (verified by my obd2 scanner).
After highway driving, truck brings temp down at idle speed without issue and it idles at 190.
I've done a paper test on the radiator (meaning will it hold the paper up against the condenser/radiator) and at idle the fan rotates but doesn't hold the paper up. With the A/C on at idle, it holds the paper and the fan gets louder (so it must be somewhat getting more locked) but the temps go up. At higher engine speed like 2,000 RPM (while sitting in driveway) the clutch fan doesn't seem to be locking up and the temp starts climbing to 200-202. Only other symptom is that the upper hose seems to be pressurized (or more than I remember it being anyway).
I'd guess the issue is the fan clutch is letting go (seems to be original) but also I hesitate on throwing parts at it when (a) the highway speed temp shouldn't be affected by the fan clutch (b) it does seem to be somewhat working when the A/C comes on.
Thoughts?
O.
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