A guide on how to replace an inlet manifold yourself
Estimated time: approx 3 hours Difficulty: Hard
Begin by disconnecting the battery. Disconnect the negative terminal first so that you don’t get any sparks and damage any of the electrical parts. This will allow you to work with any electrical parts with maximum safety.
It’s a good idea to label the different connections and hoses as you go along and write down which part was removed and in which order. This will be a great help when it comes to putting it all back together.
The exact processes followed may differ slightly from vehicle to vehicle, but this should give you a good idea. Depending on your vehicle there may be an engine cover which you need to release in order to get access to the manifold and other parts. Unscrew this cover.
Now disconnect all pipes, wires and connections, labelling where you took each of the different connections from. These connections will either need clipped out, unscrewed or unbolted.
Next you want to disconnect the air filter. Remove the screws on the cover to reveal the filter, and remove this part. Remove any hoses connected from the engine to the filter.
You will need to remove the alternator by unbolting the housing, disconnecting any electrical connections and removing the belt by pulling on the tensioner to release the belt. This will now allow you to remove the actual alternator.
Now you want to remove the throttle body by disconnecting the electrical connections and any hoses, and removing the throttle cable and housing. Unbolt the throttle body and complete remove from the vehicle.
You might want to drain some of the coolant from the reservoir to avoid any coolant getting into any parts.
Remove the connection of the radiator hose and any other electrical connections connected to the manifold, remembering to label the connections.
Disconnect the two fuel lines from the fuel rail. You will need a specialist tool to disconnect them, which you can get from most automobile stores. Watch when disconnecting these lines as there may be a little pressure and you don’t want the fuel to spray in your eyes. Wear goggles when doing this.
Disconnect the bolts holding the fuel line in place. Pull the fuel line up which will also remove the fuel injectors with it. If any injectors get stuck in place, pull them out individually by wiggling them out.
Now unbolt the coil packs, removing the bolt from each one and remove from the vehicle. Remove the coolant sensor and thermostat, which when removed will allow you to remove the intake manifold.
There will be several bolts holding the manifold to the cylinder head. Remove these bolts and then completely remove the old manifold. You will now need to clean this area up but remember to block the intake cylinders up so no dirt or debris gets down into the engine. Also remember to remove the old manifold gasket and give this surface a good clean, ready for the new part to be installed.
Fitting the new inlet manifold
Check your new inlet manifold which may have the gaskets fitted to the bottom. If not you will need to put the new gasket in place before fitting the manifold. Remove the blocks from the intake cylinders and place your new part into place. Bolt this to the cylinder head, placing each bolt in by hand and then tightening them securely to the cylinder head. Your new manifold will come with instructions on the sequence to tighten these bolts and how tight they must be. Follow these instructions carefully.
Replace the coil packs, bolting them securely and place the fuel line and injectors back into place. Bolt the fuel line back to the manifold, ensuring each injector is securely in place.
Fit the thermostat and coolant sensor back on and all connections that you had removed. Now you can fit the throttle body back in place. Bolt this to the manifold and connect any connections and hoses that you have previously removed. Reconnect the throttle cable and housing.
Put the radiator hose back on, securing it in place and any other connections that need put back on. Now re-connect the fuel lines by clicking them back in place.
Fit the alternator and bracket back in place, re-connecting any connections and then replace the air filter hose. Everything should now be re-connected, so now top up the coolant reservoir and re-connect the battery.
Start the engine to check that it’s working as it should. This completes the installation of the intake manifold.