This happens when accelerate. What is the problem?
There’s probably air trapped in the cooling system.
The air rises into the heater core becuase that’s the highest point of the cooling system. So when you accelerate, you hear the coolant rushing into the heater core and pushing the air out causing the gurgling sound. The reason the noise occurs is because when you accelerate, the engine turns faster thus causing the water pump to turn faster.
Here’s how to remove air from a cooling system. Get the engine up to operating temperature. With the engine idling, loosen the upper radiator hose clamp. Take a small flat bladed screwdriver and insert between the upper radiator hose and the radiator hose neck. Allow the engine to continue to idle until all the air is purged from the cooling system and nothing but coolant comes out. Remove the screwdriver and retighten the hose clamp.
Be very careful with Testers solution…A hot system will be under considerable pressure…The hose could blow off when you loosen the clamp.
Your system has coolant reservoir tank that is also pressurized when the system is hot…When it’s COLD, remove the cap and add some 50-50 coolant mix up to the “full” mark. The system is designed so any air will be trapped in this coolant tank…
When my 94 started doing this, there was a tiny leak in the heater core. I hope you have better luck than that. The assembly line for this car starts with a heater core on the belt. As it goes down the line, they build the rest of the car around it.