Engine/Transmission (1998.5 - 2002) Temp Running Hotter than normal

[KR4HS]

The temp problem started 3 days ago. Anytime running highway speeds the temperature rises as high as 210 - 220 depending on how hard you are running. If you keep the EGT below 600 and cruise at 55 - 60 you can keep the temperature just above 190. I just replaced the thermostat with a Cummins 180 deg P/N 3967195 it didn't seem to help. I still hear the fan noise after it warms up, I have plenty of heat, so assumed the pump was pushing coolant through the bypass. I also felt the lower radiator hose and it is cool to the touch. (gets warmer near the block) The EGT at cruise is running slightly higher than normal for the same steady speed and it takes a lot longer to cool to below 300 deg at shutdown so I assume this is not a guage or temp-sensor problem.

Thanks in advance - George

 

[BillGotthelf]

Well I know its not to cold in Titusville so how is your fan belt? Last guy with your complaint did not have a fan belt. Other areas to cause what you describe-debris in front of radiator(love bugs maybe), radiator fluid very low, coolant pump problems or even a collapsed radiator hose. Good luck.

 

[KR4HS]

You are right about it not being too cold here in Titusville!

As for the belt, it is new and intact, no leaks, full coolant system and no obstructions in the radiator.



It is looking more like the pump. I just got back from picking up the wife and she was complaining about the heater being too hot, so I turned it off and the temp went way up to the top of the operating range. With the heater on I can keep it just above normal. I haven't ever had problems with over-temp even while pulling my fifth wheel in the mountains.

Thanks for the help,

George Smith

 

[RobbyRam]

I had the same symptoms as you and this was my problem:



The 'blow-by' bottle was full and blowing oil all over my radiator and the area between the a/c radiator and the H2O radiator. I pressure washed both radiators at the car wash and emptied the bottle and the overheat problem went away. Worth a try?

Bob in Sacto

 

[KR4HS]

Update - Water pump has now been replaced - No Joy!

Ran it at 75 mph down one exit of 95 and returned and the temp climed to the top of the Operating Range. Back home I opened the hood and the Radiator cap was cool to the touch as was the coolant inside (when I shoved my finger into the cold coolant), no pressure as you would expect. No evidence of coolant loss externally or in the oil. Instrument Diagnostic was normal There is evidence of a slight amount of coolant flow, looking into the radiator after the thermostat opens but not much. As I said before I am getting heat in the cab soon after running so it is evidently pushing fluid through the by-pass side of the thermostat. I will change the hoses and anti-freeze this week-end and see if I can find any obstruction at the lower end of the block at the hose.

 

[klaybus]

Water Temp

Check the radiator to see if it's PLUGGED. Your describing exactly what my apprentice was going through with his Four-Runnner. Truck kept over-heating unless he ran his heater & drove nice.

New radiator solved problem. Worth looking into. As mentioned above, clean the front & have flow tested.



Good luck.



Clay

 

[KR4HS]

Well- after two thermostats (Original and Cummins) the problem is fixed. The second one made ran cooler but when I ran it at highway speeds of 70 or above it would rise to the top of the Operating Range, especially with the heater off. I picked up another from Dodge which was a different design than the other two and it is running normal again. It comes up to temperature and stays just below the 190 degree mark no matter how you drive it, with or without the heater on. I would not have believed that I would have gotten a bad one from Cummins but I guess it does happen. I boiled the replacement and it appeared to open slightly but the original did't move at all when it was boiled.

Thanks to all for your suggestions.



George