Ford E-350 Econoline (1980-1994) Engine Coolant Thermostat Guide
Keep your van's engine temperature in check by understanding thermostat failure and choosing the right replacement part.
- A failing thermostat can cause overheating (stuck closed) or poor performance and fuel economy (stuck open).
- For the 7.3L IDI diesel engine, using a high-quality 195°F Motorcraft or Navistar thermostat is critical for proper operation.
- While affordable, many cheap aftermarket thermostats have a poor reputation for reliability; spending a little more on a reputable brand like Stant or OEM can prevent having to do the job twice.
- Replacement is straightforward on gas engines but significantly more involved on the 7.3L IDI diesel.
Is Your E-350's Thermostat Failing?
A thermostat is a simple part, but when it fails, it can cause noticeable problems. Most failures happen in one of two ways: stuck open or stuck closed. Recognizing the signs early can save you from bigger headaches, like engine damage from overheating or poor performance from an engine that never warms up.
Common Symptoms of a Bad Thermostat
🎬 Watch: How to spot symptoms and test your thermostat- Engine Overheating: If the thermostat is stuck closed, coolant can't get to the radiator to cool down. Your temperature gauge will climb into the red, and you might see steam from under the hood. This is the most serious failure and requires immediate attention to prevent engine damage.
- Engine Running Too Cold: If the thermostat is stuck open, coolant flows to the radiator all the time. The engine will take a very long time to warm up, or may never reach its normal operating temperature, especially in colder weather. This leads to poor fuel economy, increased engine wear, and a heater that doesn't blow hot air.
- Erratic Temperature Gauge: A faulty thermostat can cause the temperature needle on your dash to swing back and forth unpredictably, moving from cool to hot and back again.
- Poor Heater Performance: If your cabin heater blows lukewarm air or takes forever to get warm, it's often because the engine isn't reaching the proper temperature due to a thermostat stuck open.
- Coolant Leaks: A thermostat that is failing or has been installed incorrectly can cause coolant to leak from the thermostat housing area.
Choosing the Right Aftermarket Thermostat
For a vehicle from this era, aftermarket parts are the most common choice. However, quality varies significantly. While an OEM Motorcraft thermostat is often recommended by long-time Ford truck owners, they can be harder to find and more expensive. When shopping for an aftermarket part, consider the following brand reputations based on owner experiences.
Aftermarket Brand Quality Tiers
| Tier | Brands | Notes |
|---|---|---|
| Premium / Performance | Mishimoto, Edelbrock, Mr Gasket | These brands often offer higher-flow designs or more robust construction. Mishimoto is sometimes seen as a quality alternative to OEM. Edelbrock and Mr. Gasket are well-known performance brands that may offer lower temperature options for modified engines. |
| Standard / OEM-Equivalent | Stant, Gates | Stant is often considered a reliable mid-tier option by many mechanics and DIYers. Gates has a more mixed reputation; some users have good experiences, while others report premature failures or inconsistent temperatures. |
| Economy | Motorad, Store Brands | Many forum users strongly advise against using the cheapest thermostats, citing high failure rates right out of the box and poor temperature regulation. Some sources claim that Motorad manufactures thermostats for other brands, leading to widespread quality control issues. While the low price is tempting, the risk of overheating or having to do the job twice may not be worth the savings. |
Pro Tip for 7.3L IDI Diesel Owners: It is critical to use the correct 195°F thermostat. The OEM Motorcraft (Part No. E5TZ-8575-C) or the equivalent Navistar part is highly recommended by specialists for these engines to ensure proper performance and longevity.
How Much Does a New Thermostat Cost?
Replacing the thermostat on a 1980-1994 E-350 is one of the more affordable repairs you can make. The part itself is inexpensive, but labor costs can vary depending on your engine.
Estimated Cost Comparison
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Part | $7 - $70 |
| New OEM (Motorcraft) Part | $25 - $80 |
| Shop Labor | $100 - $250 |
| Total Professional Replacement | $110 - $320 |
Frequently Asked Questions
What temperature thermostat should I use?
For most stock gasoline and diesel engines in the 1980-1994 E-350, a 195°F thermostat is the standard and recommended temperature. This allows the engine to operate at its most efficient temperature. Using a lower temperature thermostat (e.g., 160°F or 180°F) is generally only recommended for highly modified engines or specific racing applications and can cause the engine to run too rich in normal use.
Can I just remove the thermostat and run without one?
This is not recommended. Running without a thermostat will cause the engine to warm up very slowly and likely never reach its proper operating temperature. This leads to poor fuel mileage, increased engine wear, and can fool the engine management system on fuel-injected models into running rich constantly.
How difficult is it to replace the thermostat myself?
For most gasoline engines (like the 5.8L V8), the job is relatively easy for a DIYer. The thermostat is typically located where the upper radiator hose connects to the engine. 🎬 See this step-by-step replacement guide for Ford V8 engines However, for the 7.3L IDI diesel engine, the job is more complex and involves removing the alternator and other brackets to gain access, making it more difficult.
🎬 Watch this detailed walkthrough for 7.3L IDI diesel thermostat replacementWhy is my van still overheating after replacing the thermostat?
If you've replaced the thermostat and the engine still overheats, there could be other issues. Common culprits include air trapped in the cooling system that needs to be 'burped', a clogged radiator, a failing water pump, a bad fan clutch, or even a defective new thermostat (especially with budget brands). Also, ensure the thermostat was not installed backward.
Helpful Videos
Technical Specifications
OEM Part Numbers: E5TZ-8575-C
Standard Temperature Rating: 195°F (90.5°C). Location varies by engine: On gas engines, it's typically in a housing where the upper radiator hose meets the engine block. On 7.3L IDI diesel engines, it is located on top of the water pump, beneath the alternator and fuel filter housing.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Ford E-350 Econoline: