1. Look for signs of damage. Check the turbos for any signs of damage, such as cracks, leaks, or loose parts. If you see any damage, it's possible that the turbo is bad and needs to be replaced.
2. Listen for unusual noises. When the turbos are working properly, they should make a slight whistling sound. If you hear any other noises, such as a grinding noise, it's possible that the turbo is bad.
3. Check the boost pressure. The boost pressure is the amount of pressure that the turbos are producing. If the boost pressure is too low, it's possible that the turbo is bad. You can check the boost pressure using a boost gauge.
4. Check the exhaust gas temperature. The exhaust gas temperature is the temperature of the gases that are coming out of the engine. If the exhaust gas temperature is too high, it's possible that the turbo is bad. You can check the exhaust gas temperature using an exhaust gas temperature gauge.
5. Have the car inspected by a mechanic. If you're not sure whether or not your turbos are bad, you can have the car inspected by a mechanic. A mechanic will be able to diagnose the problem and let you know if the turbos need to be replaced.
Here are some additional tips for checking for bad turbos on a 300ZX:
* Make sure that the engine is running properly before you check the turbos.
* Be careful when working around the turbos, as they can be very hot.
* Wear gloves and eye protection when working on the car.
