Car running hot.

ANSWER : There could be an issue with the cylinder head gaskets. Antifreeze can break down and become acidic if not replaced as normal maintenance. The head gasket material erodes and can cause engine compression to build up in the coolant system. This will prevent the flow of coolant which can create an overheating condition.

There is a test that can be done to check whether there is carbon monoxide in the coolant system; it involves special equipment.

I recommend having your overheating condition inspected, and perhaps have a block test performed.

ANSWER : Hi there. Most of the time, overheating issues are caused by a radiator leak, leak in the coolant lines, or a failed thermostat. The worse case scenario is that you’d have a blown head gasket.

However, if you’re seeing small drips on the ground, the leak could be coming from one of the hoses, which might also introduce air pockets into the coolant line. This could be what’s causing your overheating situation. However, it might be a good idea to have a local certified mechanic stop by your home to do a complete cooling system inspection. That could save you a lot of money instead of replacing parts that you are unsure are faulty.

ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

ANSWER : Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator. Lastly, you may have a failing cylinder head gasket allowing coolant to leak from the water passages into the cylinders resulting in the coolant being burnt in the combustion chamber with the fuel. If this is the case, you may also notice a bit of white smoke coming from your exhaust which is a product of the coolant being turned into a steam like vapor. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

ANSWER : I have only seen this situation once in my 30+ years and it turned out to be a broken crankshaft pulley. Belts are driven by the engine. The crankshaft pulley spins the belts, which in turn spin the air conditioner compressor, power steering and water pumps, and the alternator. The vehicle should be towed to your local repair shop and not driven. Without the water pump spinning to circulate the coolant, the engine will quickly overheat and result in more extensive damage.

ANSWER : Hi, thanks for writing in. It all depends where the smoke is coming from. If it is from the exhaust then your engine be running rich and starting to foul out the spark plugs. Have the computer tested to see if any codes are present that could indicate what is causing the smoke. If you see smoke from the engine compartment then you may be running the engine hot due to low airflow over the radiator. Have the cooling fan checked to make sure it is running. If it is running and the vehicle has the AC running and the blower is on or near high then you may be using more energy than the alternator can keep up with. This can cause the radiator fan to not turn as fast as it should and let the temperature to rise if idled for long periods. 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 : Your question makes me think of a case I ran into a few years ago. The owner had modified his car but when he installed his fans, one of them was wired backwards so the fan ran in reverse. The two fans were fighting each other which was just like having no fan at all, so the car heated up while it was sitting still then it cooled off when moving. Check the rotation of both the fans before you check anything else. If that’s OK, you may be able to track down the problem with a non-contact thermometer, follow the course of the coolant with the beam. The radiator should be about 30 degrees or more cooler at the exit than at the entrance. If you need help with this, contact Your Mechanic. They can send a technician to your home to check out your overheating problem and let you know what can be done for it.

ANSWER : There are a couple of approaches to take here – either start from the battery and work "towards" the fuel pump, fuse box, ignition switch, fuel pump relay, and wiring connections in between. Or, as you have done, start at the pump with 12v, and move backwards towards the battery. This will require a GM service manual, or wiring diagram at least, with connection locations as well.

I would recommend having a certified technician from YourMechanic diagnose this starting issue, get an accurate assessment of damage and cost estimate for repairs. YourMechanic.com can dispatch a mobile, professional mechanic to your location for this repair.