Engine Coolant Thermostat Guide for the 1973-1980 Dodge CB300
Keep your classic Dodge van's engine running at the right temperature by choosing the correct thermostat.
- A failing thermostat can cause your CB300 to overheat (stuck closed) or run too cool (stuck open). Overheating is a critical issue for these heavy vans.
- Your 1973-1980 van does not have a computer to trigger a check engine light for this issue; you must rely on the temperature gauge and other physical symptoms.
- Consider a 'Fail-Safe' thermostat from a brand like Motorad, which is designed to fail in the open position to prevent engine damage from overheating.
- Replacement is a manageable DIY job, but access to the thermostat housing can be tight and may require moving other engine accessories.
Signs of a Failing Thermostat in Your CB300
A bad thermostat can cause problems that are easy to spot. Because these vans work hard, paying attention to the temperature gauge is important. A failing thermostat can get stuck open or closed, each causing different issues.
If the thermostat is stuck closed:
- Engine Overheating: This is the most serious symptom. The temperature gauge on your dashboard will climb into the red zone because coolant cannot get to the radiator to cool down. For a heavy CB300, this can happen quickly, especially when hauling a load or going uphill.
- Coolant Leaks: Extreme pressure from overheating can cause coolant to leak from the thermostat housing or other weak points in the cooling system. You might see puddles of green or orange fluid under your van.
- Strange Noises: You might hear rumbling or gurgling sounds from the engine area, which can be the sound of coolant boiling.
If the thermostat is stuck open:
- Engine Runs Too Cool: The temperature gauge may never reach the normal operating range, or it might drop while you're driving, especially downhill.
- Poor Heater Performance: If your engine doesn't get hot enough, the heater won't blow warm air into the cabin. This is most noticeable in cold weather.
- Reduced Fuel Economy: An engine that runs too cool is not efficient and will use more fuel.
A Note on Check Engine Lights
Modern cars will trigger a Check Engine Light with codes like P0128 for a thermostat issue. Your 1973-1980 Dodge CB300 does not have this computer system, so you must rely on watching the temperature gauge and looking for the physical symptoms listed above.
🎬 Watch: A visual guide to signs of a failing thermostatChoosing the Right Aftermarket Thermostat
Since original Mopar parts for this van can be hard to find, the aftermarket is your best source. The brands available offer different levels of quality and performance.
Standard Replacement Thermostats
These are great for daily driving and normal use. They are designed to meet original factory specifications.
- Gates: A well-known brand with a long history. However, some users in forums report that recent quality can be inconsistent and that some Gates thermostats may be made by other companies like Motorad.
- Motorad: This brand offers a wide range of thermostats and has mixed reviews. They are known for their "Fail-Safe" design, which is built to lock in the open position if it fails. This prevents a catastrophic overheating situation, making it a smart choice for peace of mind.
- Calorstat: Often considered an OEM-quality supplier, making it a reliable choice for a standard replacement.
Performance & Heavy-Duty Thermostats
If you use your CB300 for heavy hauling, live in a very hot climate, or have a modified engine, a high-flow thermostat can provide better cooling control.
- Mr. Gasket: Mentioned in Mopar forums as a good high-flow option that allows more coolant to pass through when open.
- Edelbrock & Mishimoto: These are performance brands trusted by enthusiasts. They often use higher-quality materials and construction designed for demanding conditions.
What Temperature Rating Do I Need?
Thermostats for these Dodge engines typically come in 180°F or 195°F ratings. A 195°F thermostat is usually the standard factory temperature for better emissions and efficiency. A 180°F thermostat will open sooner, which some owners prefer in hot climates or for performance applications to keep the engine running slightly cooler. For most stock applications, a 195°F thermostat is the correct choice.
🎬 See how to test your thermostat using the boiling water methodAftermarket Thermostat Cost for 1973-1980 Dodge CB300
| Part Type | Price Range |
|---|---|
| Standard Aftermarket Thermostat | $7 - $25 |
| Performance / High-Flow Aftermarket Thermostat | $25 - $57 |
| Thermostat Gasket (if not included) | $2 - $5 |
(Prices are estimates and do not include shipping or taxes.)
Frequently Asked Questions (FAQ)
How difficult is it to replace the thermostat on a CB300?
The difficulty is about a 2 or 3 out of 5. The thermostat itself is simple to replace, held in by a housing with two bolts. However, on these vans, access can be tight. You may need to move accessories like the alternator or A/C compressor bracket out of the way to reach the housing, which adds time to the job.
🎬 Watch this step-by-step thermostat replacement walkthrough for Dodge vansIs an original Mopar thermostat better than aftermarket?
Many mechanics prefer using original equipment (OEM) parts. However, for a vehicle of this age, a true Mopar part may be unavailable or could be a re-packaged part from an aftermarket brand anyway. A high-quality aftermarket part from a reputable brand like Stant, Mishimoto, or a Motorad Fail-Safe is an excellent and reliable choice.
What is a "fail-safe" thermostat?
A fail-safe thermostat, like some models from Motorad, is designed with a special locking mechanism. If the thermostat fails, it is engineered to lock itself in the open position. This allows coolant to continue flowing to the radiator, preventing the engine from overheating and letting you drive the vehicle to a safe location for repair.
Do I need to replace the gasket too?
Yes. Always use a new gasket when replacing the thermostat to ensure a proper seal and prevent coolant leaks. You should also clean both mating surfaces on the engine and the thermostat housing thoroughly before installing the new gasket and thermostat.
Helpful Videos
Technical Specifications
Common temperature ratings are 180°F and 195°F. The thermostat is typically a mechanical wax-pellet type valve. The correct choice depends on the original engine specification and operating climate.
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.
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Signs of a Failing Thermostat in Your CB300
- A Note on Check Engine Lights
- Choosing the Right Aftermarket Thermostat
- Standard Replacement Thermostats
- Performance & Heavy-Duty Thermostats
- What Temperature Rating Do I Need?
- Aftermarket Thermostat Cost for 1973-1980 Dodge CB300
- Frequently Asked Questions (FAQ)
- 🎟️ Get 5% Off