Dakota Forumz banner

21 - 26 of 26 Posts

·
Registered
Joined
·
566 Posts
Steve, relay for the radiator fan is in the top left corner in the diagram at post #16 in this thread. Power for the fan comes from the 50 amp fuse 15 in the Power Distribution Center (same diagram). There is no fuse for the radiator fan in the junction block at the left end of the dash. According to the FSM, the radiator fan should run any time the a/c is selected, or if coolant temperature exceeds 217° or 230° (FSM shows two different values in different places). Wire carrying power to the fan is light green.
 

·
Registered
Joined
·
22 Posts
Just a couple of thoughts Steve. You should try to artificially power and ground the fan to see it it works before jumping to buy a new one.
And a FYI on my own Dakota I tried an experiment about 2 years ago now. I removed the mechanical fan completely and ran my truck. To my surprise it didn't overheat! The electric fan was able to handle any cooling situation that I encountered. As I say I have been running the truck this way for over two years now with no issue. This was good for about a 1 mpg increase on the average. YMMV
 

·
Registered
Joined
·
96 Posts
Discussion Starter #23
Thanks, turning the cover over I found the ledger and relay location. A new relay is cheap and they hardly ever fail. I will check the fan motor before changing it. I now wonder if the electric fan has ever worked since we have had the truck one year. The mechanical fan is always spinning and this heating issue began with the long drive though lines with mid to high 90s temps. Turning off the AC and switching to full temp heat and fan does bring engine temp down but no help for the driver.
I also like the idea of improved MPG and know the mechanical fan draws power. Of course where would I be now with a failed electric fan? One thing I have noticed since this began is I'm not sure what temp 1/8 inch above the left hash mark indicates. The reason I ask is for the last year 13,000 miles more less that is where the gauge stopped regardless of speed, load, AC or outside temp. Since flushing the system twice it takes longer to reach normal ( for us ) temp and sometimes with low outside temp will run lower than what I have come to know as normal. I have the new thermostat and water outlet for when I remove and clean the intake. Plan is a compression test and leak down to decide if heads will support another 25,000 miles. Steve
 

·
Registered
Joined
·
566 Posts
The FSM states that the lower mark on the temp gage is about 130°, and the upper mark is about 250°. The needle movement is evenly graduated between the marks, so half way on the gauge is about 190°. Our systems use a 20psi radiator cap, where the boiling point of 50/50 coolant mix is about 275°, so even at the high mark on the gauge, the system should still not be boiling. But you wouldn't want to go much higher. According to the FSM, the "check gauges" light will be illuminated at 251°.

My gauge rarely goes above a third of the way up, even on hottest days (about 175°). But I have a manual transmission (no load on the cooling system to cool the transmission), and I don't pull any loads.
 

·
Registered
Joined
·
1,233 Posts
One thing I have noticed since this began is I'm not sure what temp 1/8 inch above the left hash mark indicates.
Pick up an ELM327 Bluetooth/OBDII adapter, and install Torque Free on your Android phone (or there's similar products for iDevice owners).

See what the ECU THINKS the temp is.

RwP
 

·
Registered
Joined
·
96 Posts
Discussion Starter #26
The truck continues to throw codes. Random misfire most recently. I have noticed with the cooler temps the engine temp is closer to the first hash mark. Also my high speed running issues have stopped and the idle has returned to normal. The last code was P0300 on the last very hot day. Steve
 
21 - 26 of 26 Posts
Top