Aside from topping up your coolant, there are a few other simple maintenance tasks that can be carried out with relative ease by the home mechanic. We’ll have a look at them below, and will address the various tools and components that you may need to do-it-yourself.
Note: NEVER carry out any work on your cooling system when the motor is hot. You may be seriously scalded since the fluid gets up to some pretty high temperatures.
Flushing your cooling system
Your cooling system is sealed by various valves and taps to ensure that under normal operating conditions the fluid doesn’t pour out. When you want to change the fluid though, you’ll need to open up these taps and allow this to occur. Emptying the contents of the radiator is simple enough since usually there will be little plastic bungs at the bottom of it, that can be unscrewed. To assist the fluid in draining out, you should open the cap on the radiator as well. You shouldn’t need any special tools to do this part, though always be sure to drain old coolant into a tray and dispose of it properly - ie. NOT into a gutter or your home plumbing!
Emptying the contents of the radiator is only the first step in the process since some of the old fluid will also remain inside the connective pipework, and the motor itself. Hence, you’ll need to run some water through the system using your garden hose, to push all of the old stuff back out. Once you have done this, close up the drain taps and refill the system according to either your car or the coolant manufacturer’s recommendations, then run the car to allow the water pump to circulate the new fluid and expel any air bubbles. (You may need to top up the radiator after this.)
Replacing worn hoses
As mentioned before, the hoses in your cooling system may perish and deteriorate over time. When this occurs, leaks may develop and small particles of material may end up getting circulated within the system and potentially cause blockages in the galleries within your motor. Replacing any worn hoses will first require that you drain the fluid out. Keep a drip-tray and rags handy because there will always be a few drops of fluid still lurking within the system! Once done, the next step is to remove the retaining clamps that hold your hoses on. There are a few different designs - some can be unscrewed using a screwdriver or socket, others will need to be squeezed with pliers and wriggled free. Since your hoses will have sat in place for some time, and been exposed to constant heating and cooling, they will usually put up a bit of resistance as you try to wrestle them off the inlets and outlets that they attach to.
Replacement hoses and clamps can be purchased for almost every make and model of car, and failing that, there are generic lengths of hose that can be cut down to suit any application. There are a few different types of hose, made from different materials and with different levels of flexibility and heat shielding. Be sure to have a chat with a staff member about the option that will suit you best.
Replacing your thermostat
As explained above, your thermostat is the valve that controls where the fluid flows as your engine heats up and once it’s up to temperature. Unfortunately, they can fail, or get blocked up and so can cause issues with how the motor runs. If the thermostat gets stuck open, then your car will have trouble getting up to temperature, and so will run badly when it is first started, and if it gets stuck closed, then the engine may overheat. Before you replace it, you can check how the thermostat has failed by running the motor and feeling the top hose that runs to your radiator. If it warms up fairly quickly, then it is likely that the thermostat is stuck open, if it stays fairly cold once the engine itself is warmed up, then it is stuck closed.
In order to replace the thermostat, you’ll likely need to drain some fluid from the system, but since they sit at the outlet from the motor, you shouldn’t need to empty all of the coolant. Most thermostats are held in place within a special housing, that will be attached to the head of your motor with a few bolts. Be sure to disconnect the negative terminal from your battery if the job requires that you unplug any wiring - Many thermostat housings have the wiring for the temperature gauge on or near them. You’ll need to remove the hose clamp and disconnect the hose from the thermostat housing, then undo the bolts and pull the housing away from the engine. If the housing is stubborn, you can tap it with a piece of wood or a rubber mallet. NEVER pry it off with a screwdriver as this might damage the surface where it mates to your engine, and so cause leaks later on. The housing will be sealed up with a gasket which will likely be damaged when you take the housing off, so it is always advisable to replace it with a new one, being sure to scrape away the remnants of the old one. (Use a rag to prevent any residue from falling into your fluid outlet) One final check you can do to see if you do need to replace the thermostat or if the problem lies elsewhere is to suspend it in a pot of water then heat it up. Most thermostats have their opening temperature stamped on them, so make sure the thermostat doesn’t touch the pot, and if you have a thermometer then check that the thermostat opens once it reaches the temperature indicated. If your thermostat doesn’t have the temperature stamped on it, heat the water up until it boils - if by then it hasn’t opened, then your thermostat is faulty.
Replacing your water-pump
Sometimes the actual pump that pushes the fluid around in your cooling system can wear out or seize up. If your car is overheating and you have eliminated the possibility of leaks or a faulty thermostat, be sure to check that the belt that drives your water pump is tight enough and that the pulley is turning as your motor runs. (You’ll usually hear a terrible squealing sound as you drive along if your belt is slipping.) If everything is in order there, you’ll want to remove the pump and check it. The first thing you’ll need to do is remove the belt from the pulley. Depending on the make and model of your car, the way that the belt is tensioned up will vary, so be sure to consult a workshop manual for guidance around how to remove it. (In fact, you’ll likely find a thorough guide on how to remove the water pump too, so you can pretty much stop reading this, and go and do it according to the manual!) Once your belt is removed, you’ll need to unbolt the pump housing and remove the pump - you can usually use a socket set for this, though in some instances, spanners will provide better access.
As with the thermostat housing, your pump will be sealed up with a gasket material. Be sure to replace this as outlined above. If your water pump is fouled up with goo, then it is a good idea to flush the whole cooling system. You will likely be able to clean the pump with some brake cleaner, and it may free it up so that it can carry on doing its job. If you do replace it, you can purchase a new water pump for your car fairly cheaply through your local store, or online. The assembly is simply carried out in the reverse order, though now may be a good time to replace the belt that you took off too.
When carrying out any of the work outlined above, be sure to use a drip tray or bucket to catch the fluid that spills out. Also make sure that you keep an adequate supply of rags or shop towels handy, since coolant can stain your garage or driveway. It is advisable to use gloves as well, since some coolants can irritate your skin. Make sure to replace worn clamps with new ones (or upgrade to screw type clamps, since the pinchy ones are downright annoying to manhandle) and also replace any gasket that you remove, and give it a better seal by using purpose-designed gasket sealant.
Fans and the temperature sensor
You can purchase aftermarket thermo-fans which can provide an added boost to your car’s cooling ability, when compared to a standard belt-driven or clutch fan, or to replace failed factory units. Be sure to follow the installation instructions thoroughly, and as with any electrical work - disconnect the negative lead on your battery before you begin. You can also purchase various sensors, switches and other electrical components to suit your car, or for custom setups both online and in-store - be sure to check that any sensor you do purchase is compatible with your car’s engine management, as each replacement will differ to suit the original manufacturer of your car’s specifications.
As you’ll no doubt be aware now, a good cooling system is imperative to the proper operation of your car. Be sure to use the best quality coolant that your budget allows, and check periodically to ensure that it is working as intended. Our summers can get pretty hot, so it’s always a good idea to give your motor every advantage it can get in dealing with that heat, as well as its own!
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