Club-S12 Username: Dan0myte
Your thermostat may be one of the most overlooked maintenance items on the vehicle. For the majority of the population, simply pouring coolant into the radiator when it's low is all that ever gets done for the cooling system. They may not realize that it's recommended that every 36,000 kms (or 20,000 miles), a new thermostat should be put in.
The thermostat has a very simple job. It stops the flow of coolant when the engine is cold, then allows the flow of coolant when the engine gets warm. If there was no thermostat at all, the engine would take a really long time to warm up. Maybe not a bad thing for performance, but if the ECU detects the engine is cold, it will inject more gas in order to help it warm up. You want the engine to heat up as quickly as possible so the ECU goes into normal fuel injection mode. When thermostats die, they usually either get jammed open or jammed close. Jammed open isn't a big problem, it's basically like not having a thermostat at all. It will take a good half hour before your temperature needle goes to the middle of the range. If it gets jammed closed, then you're in trouble. The engine will heat up very quickly and may overheat if driven for a while. Either way, it's very critical that you have a good working thermostat in your car.
Materials Needed:
- 160, 180, or 192 degree Thermostat
- Thermostat housing gasket
- Flat blade scraping device
- Variety of screwdrivers
- Small amount of steel wool
- Ratchet with 12mm Socket & Extension
The first thing you have to do is determine what degree thermostat you want to install. They are usually offered in 160 degree F, 180 degree F and 192 degree F models. This number represents the temperature that the thermostat pops open and allows coolant flow. Now, you have to remember that an engine likes to be as cool as possible. The colder it is (within reason), the better it performs. But on the other hand, the warmer it is, the better gas mileage it will get. This is the balance you have to decide on with your car.
The stock thermostat from most manufacturers is the 180 degree model. That means, when you engine hits 180 degrees, coolant begins to flow and tries to cool down the engine. It is a nice mix between economy and performance. If you are more concerned with how quickly it warms up in the winter and your gas mileage, you can choose to install a 192 degree model instead. If you are more concerned with performance and engine longevity, and don't care about gas mileage, then you can choose to install the 160 degree model. It's up to you.
So assuming you have purchased your new thermostat and gasket, let's get started.
- First thing to do is drain your coolant. There is a petcock located at the bottom driver's side of the radiator. Place a bucket underneath it and then loosen it to drain all your coolant. Once the system is empty, remove your upper radiator hose. With the hose off, locate your thermostat housing. On the CA18ET engine, it's located here:
- Clear away any vacuum lines or wires that are in the way to give you clearest view of this piece. This housing is held on by three 12mm bolts. Take your rachet with extension and remove all three. Once they are out, you can simply pull the housing away from the engine. It may be stuck on fairly well, so pull hard. This is what you will see when the housing comes off:
- Grab the thermostat with two fingers and give it a good pull to remove it from the intake manifold. Remember that the spring side goes IN. That's key to making the thermostat work properly.
- Take a scraping device now and get rid of ALL the old gasket material. It might take a while because a lot of gaskets are just left in there for years and years, but do it the right way and get all of that out of there now! Once it's all out, take some steel wool and just run it around the rim of the hole to make sure the metal is nice and clean and ready for a new gasket.
- Now looking at your new thermostat, notice that it will have a "Jiggle Valve" located on it. If you shake the thermostat, you will be able to hear it rattle. If the thermostat you bought does not have this jiggle valve, go back to the place you bought it from and get the correct kind. This valve allows trapped air to pass by and leave your coolant system. Without this valve, you can get airlock and have the engine overheat.
- Take the new gasket and the new thermostat and put them into the intake manifold hole, making sure that the spring side of the thermostat is facing inside the engine and then rotate the thermostat so that the jiggle valve is at the top of the hole. It needs to be at the highest point in order to work. Then place the thermostat housing back over the thermostat and tighten the three 12mm bolts down.
- Replace your upper radiator hose (with a new one if you old one feels soft or has cracks) and refill your cooling system with some new Prestone and you're set!