When speaking of a diesel engine, the Cummins engine is a powerhouse that demands the best care and attention. In particular, the 2012 Cummins 6.7L engine is the engine of choice for heavy-duty trucks and industrial applications because of its superior performance and rugged design. Although it has slightly decreased in reliability compared to the 5.9 Cummins, it meets the increasingly stringent emissions standards and thus becomes a popular choice among diesel engines. However, even the most rugged machines require regular maintenance and replacement of key components to keep them in tip-top shape, including the thermostat. Ever had a vehicle that just refuses to warm up in the cold? Maybe the cabin heat feels weak, and the temperature gauge takes ages to rise. Today, we’ll look in-depth at the 2012 Cummins thermostat replacement, learn what it does, identify when they’ve gone bad, and provide detailed replacement steps.
What is a Diesel Engine Thermostat?
The thermostat in a diesel engine is a temperature-sensitive valve that controls the flow of coolant. It opens and closes in response to changes in engine temperature, regulating the coolant flow to keep the engine within its optimal operating temperature range. When the engine is cold, the thermostat keeps the coolant circulating within the engine block to warm it up quickly. As the engine warms up, the thermostat opens, allowing coolant to circulate through the radiator to prevent overheating.
What do Thermostats do in Diesel Engine Under Low Temperatures?
During the cold winter months, diesel engines become more difficult to start. The thickening fuel and sluggish battery performance can make for some tough starts. Not to mention, the lurking threat of diesel fuel turning into a gelatinous mess that clogs filters and fuel lines. And let’s not forget the poor battery, its capacity sapped by the cold, leaving the starting system to shoulder the extra load. Thermostats are born to cope with the aforementioned problems. Thermostats are highly in demand during winter times, as they serve to warm up the engine quickly and keep the engine at optimum operating temperatures. Plus, they help take the heat off batteries allowing them to perform at their best. Thermostats aren’t just a part of the engine—they’re the lifeline that keeps diesel engines humming through the snow and ice.
Wonder how to choose the right lubricant for winter? Check here: How do seasons impact engine lubricant choice?
How to Tell a Bad Diesel Engine Thermostat?
A bad diesel engine thermostat can lead to a range of problems and seriously cut down your working efficiency during winter times. Here are some signs that your thermostat may need replacing.
- Overheating: The sign “OVERHEATING” light on is an obvious reminder of thermostats not opening properly. Sometimes the light was not on, but if you feel your engine running hotter than usual, be careful. It could indicate an abnormal thermostat too.
- Slow warm-up: If you find that your engine takes longer than usual to reach operating temperature, be careful with the thermostat being stuck closed.
- Erratic temperatures: Erratic temperatures refer to the coolant temperature kept rising even after the engine fan kicked in, and we had to stop twice over the summer to let it cool when it hit 230°F. If you happen to encounter the situation, it time to replace your Cummins thermostat.
- Leaking coolant: Visible leaks around the thermostat housing can indicate a worn or damaged thermostat.
2012 Cummins Thermostat Replacement Step-by-step Guide
Now that you know the signs, let’s get down to replacing that thermostat. Here’s how you do it:
Tools and Supplies at Your Disposal:
- A fresh thermostat
- Coolant for a top-up, if needed
- A trusty drain pan
- Sockets and wrenches in 8mm, 7/16-inch, and 12mm sizes
- Ratchet and extensions for those hard-to-reach spots
- A screwdriver for the finer adjustments
Step-by-Step Guide:
- Prepare the Vehicle:
- Make sure the engine is cool before starting.
- Open the radiator cap to release any pressure in the cooling system.
- Drain Some Coolant:
- Place a drain pan under the radiator.
- Locate the drain plug at the bottom of the radiator and drain about a gallon of coolant to reduce spillage when removing the thermostat housing.
- Remove the Plastic Engine Shroud:
- Use an 8mm socket to remove the bolts on the plastic shroud covering the engine’s EGR pipe.
- Temporarily remove the oil dipstick to lift off the shroud and set it aside.
- Remove the EGR Crossover Tube:
- Loosen the clamps on both ends of the EGR pipe using a 7/16-inch socket.
- Disconnect any electrical connections and remove the pipe.
- Some trucks may have an additional 8mm bolt securing the EGR tube to a bracket; remove this if necessary.
- Access the Thermostat Housing:
- Remove any remaining shielding or brackets covering the thermostat housing.
- Disconnect any sensors or hoses that obstruct access to the thermostat.
- Remove the Thermostat Housing:
- Use a 12mm wrench to loosen the bolts on the thermostat housing.
- Carefully lift the housing off, expecting a small amount of coolant to spill.
- Remove the Old Thermostat:
- Gently lift the old thermostat out of its housing.
- Inspect the thermostat and housing for damage, especially the seal around the thermostat. If the seal is worn or missing, it may have caused leaks or improper cooling.
- Install the New Thermostat:
- Insert the new thermostat into the housing, ensuring it’s properly seated.
- Reattach the thermostat housing and securely tighten the bolts.
- Reassemble the EGR Tube and Shielding:
- Reinstall the EGR tube, ensuring all clamps and bolts are securely fastened.
- Reconnect any electrical connections removed earlier.
- Refill Coolant and Check for Leaks:
- Refill the coolant if necessary.
- Start the engine and check for leaks around the thermostat housing.
- Monitor engine temperature to ensure the thermostat is functioning correctly.
Conclusion
The 2012 Cummin thermostat replacement may come not as hard as you may think. Catching the signs early can help you avoid costly downtime and keep your engine in its best shape. With our step-by-step guide, you’ll have your Cummins engine running at the right temperature, keeping it reliable no matter the weather. FridayParts is here to support you with quality engine solutions, so you can keep your Cummins powerhouse running smoothly all winter long.
