How to troubleshoot cooling system issues on a 1970 Dodge Challenger R/T?

Content verified by Michael G.
July 18, 2025
Discover step-by-step tips to troubleshoot and fix cooling system issues on your classic 1970 Dodge Challenger R/T. Keep your engine running smoothly with our easy-to-follow guide.

Experiencing cooling system issues with your 1970 Dodge Challenger R/T can manifest in several ways, such as an overheating engine, coolant leaks, or an inoperative heater. Identifying and resolving these issues promptly can prevent severe engine damage and ensure your classic car runs smoothly. To help you through this, here is how to solve this issue:

Step 1: Check Coolant Level and Radiator Cap

Start by making sure the engine is completely cool. Locate the radiator cap at the front of the engine bay; it's typically a round, metallic cap situated on top of the radiator. Twist it counterclockwise to remove it carefully. Check the coolant level; it should be near the top of the radiator or up to the "Full" line in the coolant overflow tank. Top it off with a 50/50 mix of coolant and distilled water if it's low. Inspect the radiator cap for any signs of rust or wear; replace it if necessary.

Step 2: Inspect Hoses and Clamps

Next, take a look at the radiator and heater hoses. These are rubber hoses running from the radiator to the engine and from the engine to the heater core. Check for any visible cracks, bulges, or leaks. Pay special attention to the areas where the hoses attach to the engine and radiator using metal clamps. If you notice any damage, replace the hoses and ensure the clamps are tight and secure.

Step 3: Examine the Radiator

Inspect the front surface of the radiator for any obstructions such as leaves, dirt, or debris. These can block airflow and cause overheating. Use a soft brush or compressed air to clean any blockage. Also, look for any visible signs of leaks, especially around the seams and the cooling fins. If there's any significant damage, it may be necessary to either repair or replace the radiator.

Step 4: Check the Water Pump

The water pump is typically located at the front of the engine and can be identified by a pulley connected to a belt. Look for any signs of leakage around the pump; this can appear as coolant residue or moisture. Additionally, check the belt for proper tension and condition. If the water pump shows signs of leakage or if the belt is worn or loose, these components may need to be replaced.

Step 5: Examine the Thermostat

The thermostat housing is connected to the top radiator hose where it meets the engine, usually near the intake manifold. It looks like a dome-shaped cover held down by a couple of bolts. If you suspect the thermostat is stuck closed, causing the engine to overheat, remove the housing and inspect the thermostat. If it appears stuck or faulty, replace it with a new one that matches the specifications for your Dodge Challenger R/T.

Step 6: Test the Cooling Fan

Verify the operation of the cooling fan, which can either be mechanical or electric. For mechanical fans, make sure the fan clutch (located at the center of the fan) is operating correctly and not slipping. For electric fans, ensure the fan turns on when the engine reaches operating temperature. If the fan does not turn on, check the fan motor, relay, and associated wiring for defects.

Step 7: Conduct a System Flush

If the coolant appears dirty or rusty, it might be time for a cooling system flush. Drain the old coolant by locating the radiator drain plug at the bottom of the radiator and turning it counterclockwise. Once drained, close the plug and fill the system with a radiator flush solution and distilled water. Run the engine to operating temperature, then turn it off and let it cool before draining again. Refill with the appropriate mix of coolant and distilled water.

By following these steps, you should be able to diagnose and rectify most cooling system issues on a 1970 Dodge Challenger R/T, ensuring it remains in good running condition.

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