Ford F-250: Why is My Truck Overheating?

Here are a few reasons why your Super Duty truck is overheating.

By Pizzaman711 - November 13, 2014

This article applies to the Ford F-250, F-350 Diesel (2005-2014).

An overheating truck is an early warning sign of permanent damage to come if not properly addressed and fixed. A simple $20 fix can turn into a $5,000+ fix in a matter of miles, so it's important to limit driving to an extreme minimum, even if it means calling the dreaded tow truck.

Materials Needed

  • New coolant
  • Socket set
  • Drain pan
  • Towels

Step 1 - Check coolant level

Low coolant is a major cause of overheating issues. Coolant condition can provide a good sign of how your engine is running as well.

  • If the fluid is low, it'll need to be topped off. Coolant should not be more than max, nor should it be less than min.
  • If the fluid is dark colored, flush and replace it. It's always important to keep clean fluid in your truck.
Figure 1. Check coolant level.

Pro Tip

Low coolant can be signs of other problems. If it's low you'll want to do a good inspection to check for any leaks. If you have white smoke coming from the tailpipe, it can be a sign of a blown head gasket. If you have the 6.0L motor it can also be a sign of a bad EGR cooler.

Step 2 - Check DTC codes

DTC codes can help lead you to the problem. Most diesel owners already have some form of a scanning tool to monitor temperatures, boost, etc.; for those who don't, it's recommended to purchase one. You can normally get a cheaper one that'll be able to read codes as well as monitor temperatures for under $200, which is a small investment to make sure your truck is running at its prime.

  • Plug your scanner into the OBD-II port; it's normally under the dash on the driver side.
  • Pull and record the codes you get from it.
Figure 2. Port located under the driver's side dashboard.

Pro Tip

If you do get a DTC code, you can use it to narrow down your search for the issue that's causing the overheating.

Step 3 - Check the radiator

A damaged radiator, even one that isn't leaking, can limit the flow of coolant through the system, not allowing the engine to cool itself properly. Any major damage will most likely require for it to be replaced.

  • Inspect for any big dents, gouges, bent/broken fins, etc. All of these can cause fluid to not be able to flow properly through the radiator.
Figure 3. A dented radiator.

Pro Tip

Another sign that the radiator isn't cooling properly is when both the upper and lower radiator hoses are around the same temperature when the engine is warm. Normally, the lower hose should be somewhat cooler than the upper hose.

Step 4 - Check the thermostat

It may be stuck closed. The thermostat itself is a simple and cheap swap, so even if you can't pinpoint it as the problem, it'll only set you back around $20 to try it. If the thermostat gets stuck closed, it won't allow coolant into the engine because it thinks the engine isn't warm enough. A cool upper and lower radiator hose can be a sign that the thermostat is stuck closed. You can also test it by removing it and using a thermometer and a boiling pot of water. On the thermostat it will normally have the opening temperature stamped onto it. Without letting the thermostat sit on the bottom, submerge it in water. When the water hits the opening temperature, check the thermostat to see if it opened. If it doesn't open, it'll need to be replaced.

  • Figure 4. Looking from the front of the truck.
  • Figure 5. Thermostat is located on the end of the upper radiator hose.

Step 5 - Check the fans

They might not be turning on. If fluid is moving through the system but isn't cooling, another cause can be the radiator fans. Due to the noise and the extra strain they add to the motor, these only turn on when temperatures get hot enough to warrant it. If the engine is overheating but the fans aren't running, they'll need to be serviced and possibly replaced.

Figure 6. Check the radiator fans.

Step 6 - Check the water pump

It may have seized. A failing water pump will make a grinding or whining sound when it's about to die and the sound will become exponentially louder when it dies. Another way to check it is with your car's air conditioner and heater; if they aren't working properly when the engine is warm, it's a sign that either the thermostat or water pump is bad. It's always best to replace the thermostat before the water pump because it's a much cheaper fix.

Figure 7. Check the water pump.

Step 7 - Check the head gasket

It might be blown or cracked. Unfortunately, this is one of the worst case scenarios as it will require an engine tear down to fix. However, if you have a leak but can't find it and you get white smoke from the tailpipe, it's most likely a cracked head gasket. You'll want to let a shop do the final diagnosis and fix on this if you aren't too mechanically inclined, as it can be a pretty involved job.

Figure 8. Blown head gasket.

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