With Lovert Mafukure
I HAVE replaced cylinder head gasket 3 times and the head was skimmed but car still overheats. Any help?
Overheating is quite a common problem, we have touched on it a few times and hopefully you will get to solve your problem this time. Many factors lead to the overheating of an engine. It can be the thermostat, radiator fan, the radiator, water pump, blown head gasket, warped cylinder-head, cracked cylinder-head, cracked block etc.
A thermostat is very small thing and in most cases causes the biggest problems. A thermostat is a very small device that regulates temperature. What it does is that when the engine reaches a certain temperature it opens up so coolant flows to the radiator for cooling. When the coolant is cool enough it closes. What happens when it malfunctions is that it gets stuck usually in the closed position causing the engine to overheat. Corrosion usually affects thermostats and radiators often. It’s not advisable to use water in your cooling system because it will corrode your cooling system and eventually it won’t be as efficient as it is supposed to be at its job of cooling.
Some mechanics believe thermostats are just more trouble than anything else and they simply remove them and let the engine run without them. That however, may cause some performance issues on cars like taking longer to warm up and also the engine running cooler than normal, so check to make sure that your thermostat works if your car has one. The best way to check is to remove it, throw it in a boiling pot of water and see if it opens up. It is supposed to open up at boiling point. If it doesn’t open then that is where is your problem lies, replace it.
A bad radiator can also cause nightmares similar to the ones you are having. Overtime the cooling system needs a flush and the radiator cleaned as well. Check to make sure that your radiator isn’t blocked by funny things like leaves debris of any sort on the cores because that can restrict airflow and retard the cooling action.
A bad fan on the other hand can be a problem as well. Your fan may be working but may not be coming on at the correct time. Since normally fans come on when the need arises (when engine gets hot) your temperature sensor may be malfunctioning and switching on the fans late or not at all. Check that the fans are working as they should, sometimes fans run but at a retarded speed. Having changed the head gasket more than twice is an indication of bigger problems than just a blown head gasket.
Water pumps do go bad as well and when they do go bad they will seize to do their job of pumping water to and from the engine. If you open the radiator cap when the car is running you should be able to see the water flowing in a certain direction, that will show you that the water pump is working, if the water is just still then maybe your water pump impellor is faulty. Remember you can only see the flow of coolant when the thermostat opens so wait until the engine reaches operating temperature to check for such. Radiators are always under pressure and the coolant can cause some serious burns be careful when removing the radiator cap.
Blown head gasket causes engine to overheat in most cases depending on the extent of the head gasket leak. Seeing that you have replaced the head gasket three times we will rule out the head gasket being a problem. Let’s assume your car had overheated when you changed the head gasket. Was the head skimmed flat or it still warped? Your mechanic should be able to tell. You can use a straight edge to check for flatness on the cylinder head surface. On the other hand, how many times has the cylinder-head been skimmed? If more than once then you need a thicker head gasket not the standard thickness.
In worst-case scenario, your head or the block may be cracked. There are engines that are well-known to have weak designs and eventually crack no matter how careful you are.
An example is the Toyota 2LT diesel engine. Most 2LT owners or mechanics know that those were designed to crack and fail eventually. So check for cracks, do compression tests and leak down tests to rule out any leaks and cracks. Just changing the head gasket will not help you, you need to fix the problem that’s causing head gasket failure first. All the best mate.
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