Overheating Issue

[Sandflea]

My '06 went into limp mode pulling my FW up a steep pass (10,900') in Colorado about three weeks ago. There was no place to pull over, so I made the last 2 miles of a 7-8% grade at about 18 mph. When I was finally able to pull off the road, the engine temp gauge was about 3/4 of the way between 200 and 245. I let the truck idle for about 20 minutes, the temp returned to normal, and limp mode cycled off. I threw an engine coolant code, but that was it. When I got home, I checked the space between the radiator and the transmission cooler, and ended up cleaning out a thick collection of bugs. A couple of days later, the #2 injector failed (again), and was replaced. Don't know if the two issues are related. I was in Silverton again last weekend, without the FW, and I noticed that the engine temp gauge climbed quite a bit higher than than it usually does on the same stretch of road, when I'm not towing. Could I have fried the thermostat when the engine temp got high in limp mode? I'm at 145,000 miles, and am going to flush the radiator, but would like to know if I should replace the thermostat at the same time.

Thanks!

 

[Prairie Dog]

Although the stats are supposed to fail in the open position, I would replace it while flushing the radiator just as a maint. item.
They're operation can get lazy. Replace it with a genuine Cummins part because many of the aftermarket parts don't flow correctly under extreme conditions.
Also, pull the belt off the water pump and make sure there's no play or roughness to the pump. It may not be a bad idea to pull it out and make sure all the fins are still intact - sometimes the pump gets a little play and those fins/blades contact the housing causing them to snap off.

 

[Sandflea]

Much obliged! The water pump was replaced last year, but I'll look it over when I replace the thermostat.

 

[p-Bar]

How was your EGT ? also did you put brand new injector or rebuild in? Rebuilds are not recommended as they have a high failure rate.

 

[sag2]

Was the fan screaming? If not may be time for a new OEM fan.

 

[PWong]

the engine temp gauge climbed quite a bit higher than than it usually does on the same stretch of road, when I'm not towing
Suspects in order: low coolant level / insufficient air flow / defective thermostat / partially clogged radiator / cooling fan.

 

[lpennock]

I would suspect the cooling fan isn't engaging. With the computer controlled cluth it is had to check but your symptoms point to it not working.

 

[PWong]

Don't blame the cooling fan until you are sure the radiator is GOOD.
A good cooling fan would NOT help a clogged radiator with restricted coolant flow.
Most/major part of the cooling job is done by the radiator and the viscous fan.
The electric part of the fan would only come in after the radiator and the viscous fan are fully loaded and the temp still moving up.
The would be no need for electric part of the fan when on highway speed without towing unless the fan is freewheeling.

 

[ColemanR]

Mine did the same thing resently after replacing the fan turned out I had a blown fuse in the fan circuit.

 

[Bob4x4]

Don't blame the cooling fan until you are sure the radiator is GOOD.
A good cooling fan would NOT help a clogged radiator with restricted coolant flow.
Most/major part of the cooling job is done by the radiator and the viscous fan.
The electric part of the fan would only come in after the radiator and the viscous fan are fully loaded and the temp still moving up.
The would be no need for electric part of the fan when on highway speed without towing unless the fan is freewheeling.

+That makes no sense ????

 

[PWong]

+That makes no sense ????
It definite makes sensor to check the fan.
My point is don't go crazy after the fan until you confirmed the radiator is good.
Recently there were a couple of overheating threads, don't recall it's here or the other forum, the OPs chased around the cooling fan and it ended up found that they have clogged radiator.

 

[Bob4x4]

You are making it sound like there are 2 fans or 2 fan clutches

 

[PWong]

Let me try again.
There is ONE fan with ONE clutch. The clutch has TWO parts of operation, the viscous part and the electrical part.
The viscous part would keep the fan running at a speed less than the engine rpm and it's depending on the air temp.
The electrical part is controlled by the ECM when extra cooling effort is required. The fan would be locked in to the engine rpm.

 

[lpennock]

Viscous part is about 50% of engine speed and electrical part goes to about 90% of engine speed.

 

[PWong]

The fan would be locked in to the engine rpm.
Sorry the word "lock in" was NOT right.
Accoding to FSM, engine rpm/fan rpm = 500/490, 1000/950, 1500/1420, 2000/1850, 2500/2230, 3000/2440 when pin 1 of the fan connector is grounded by ECM.

 

[wcjp]

Friend and I with our own 06' Dodge's recently had weird cooling issue at the same time. I changed fluid and thermostat. Behavior returned to normal. I also bought an engine diagnostic bluetooth tool. On recent trip it was interesting to watch the computer version of events vs the analog gauge. The main reason I bought the Scantool was to monitor my erratic RPM gauge.

 

[Wingate]

Things to check..
Differential across cooler....compare inlet temp of coolant going into radiator vs temperature going out to engine. If differential is too low that would indicate the fan is not drawing enough air thru radiator. That could be due to blockage of airflow or from fan not functioning properly.
If differential is too high, that indicates excessive restriction on cooling side, susally associated with regulator.
Make sure cooling system is THOROUGHLY purged of ALL air from the highest point under the regulator.