My car overheated while on the highway. I added coolant and let the engine rest and cool down. Now the car will not start. How can

ANSWER : Hi there:

Unfortunately, there is no exact reason we can offer to you as to why the vehicle won’t start now after your overheating issue; without first inspecting the vehicle. However, if the vehicle overheated on the highway there is a high possibility that major engine damage has occurred, which is possibly why the vehicle won’t start now. This damage could include head gaskets being blown, which can cause coolant to enter the internal portions of the engine and lead to additional damage. The best thing for you to do is have your vehicle towed back home, then contact YourMechanic.com to have one of our professional mechanics complete a car is overheating inspection.

ANSWER : Hi there. For the coolant light to go out, you would need to have the coolant between the low line and the full line for the light to go out. If the coolant is low and keeps on being low, then look for any signs of coolant leaks. You may have to use a coolant pressure tester to pressurize the reservoir to allow the leak to be found.

If you need further assistance with the coolant being low and the warning light being on, then seek out a professional, such as one from Your Mechanic, to help you.

ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : It’s curious that you don’t seem to have a code in the ECM. Usually if you have a malfunction that prevents the car from starting, there will be a code resulting. That being said, it sounds like you may have an issue with a crank position sensor or an ignition control module. Both of these have a history of failing when they are hot and coming back to life again when they are cold. A bad crank sensor will almost certainly result in a code, but an ignition module might not. It’s hard to say what the issue is about the door lock, but it is probably not related.

Both of those pieces are pretty expensive, so I don’t recommend just replacing them to see if it works. Your best course of action would be to have a mechanic check it out so you don’t replace anything you don’t need. YourMechanic can send a technician to your home to diagnose the starting problem firsthand and recommend an accurate fix.

ANSWER : Hello, thanks for writing in. I recommend checking for spark. The overheat may have damaged an ignition coil or possibly a camshaft sensor or a crankshaft sensor. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

ANSWER : Depends on if you drove the vehicle with straight water or nothing in the cooling system. If there was nothing in the cooling system, then the head gasket may have burned causing the coolant to slightly leak into a cylinder making the smoke. If the smoke is white and smells sweet, then coolant is being burned. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your engine after being overheated.

ANSWER : The first thing I would do is have the turbo/intake system ’smoke’ tested or visually inspected for any leaks. Without a smoke machine, you could spray your engine and turbo system with brake cleaner and listen for idle changes to help determine if there is a leak. The brake cleaner method is not as effective as using a smoke machine.

Next, checking your fuel pressure is in order to see if you lose fuel pressure as it sits or if the fuel pump in the tank is weak. If the fuel pump in the tank is weak or losing pressure, it would cause the engine to crank as you mentioned. Performing a fuel pressure test is not easy and requires a special tool. If you want to have this looked at a technician from YourMechanic can come to your car’s location to diagnose your stalling issue.

ANSWER : Hi there. Check the battery cables and make sure that they are tight and clean. Then check the battery voltage and see if it has a voltage of 12.6 or 12.4. If the battery is less than that, then the battery needs charged. If the battery has 12.4 volts or higher, then place a load tester on the battery and see if the battery can hold a charge when a load is applied. If the battery drops under 9.6 volts, then the battery is no good and needs replaced. If the battery drops to 11.5 volts, then there is a dry cell and possible a burned cell and the battery needs replaced. If you need further assistance with testing your car battery, then seek out a professional, such as one from Your Mechanic, to help you.