Replacing the Inlet Manifold Gasket

For sometime the car had been suffering from a very slow coolant leak but all attempts to locate it's source had proved negative. There was no sign of mayo (emulsified oil and water) in the coolant or engine oil, and no indication of head-gasket failure, but I just simply could not find where the coolant was going. A few weeks ago, the engine started to misfire when starting up, but would, after a few minutes, then to run smoothly. Changing the plugs, leads, distrubutor cap and rotor did not cure the problem. Finally, using a mirror, I discovered a few drops of coolant under the inlet manifold.

Removing the manifold is not a particularly difficult job, but it is awkward when done with the engine in situ in the car. Four of the nuts holding the manifold to the engine block are tucked away under the mainfold, and the only way you can see them is by using a mirror!

To drain the coolant, it is best to get the rear of the car up axle stands, so you can release one of the hoses from the underfloor pipes and drain the coolant into a bowl. ( If you keep things clean then there is no reason why you cannot re-use the coolant). Then, unless you are eight foot tall, you need to drop the car again, since you are about to do a lot of reaching over the boot and down into the rear of the engine.

You will also need a torque wrench and socket set with an extension bar of about 235mm (9 1/4 ") long.

Release the hood clamps above the windscreen, unzip the rear windscreen, unclip the 5 clamps, and fold the rear of the hood foward, being careful not to crease the plastic window and secure it out of the way with a length of string.

Remove the parcel shelf trim and the sound deadner pad.

Remove the 11 bolts securing the engine cover and remove the cover.

Inside the boot, release the 4 retaining clips along the front edge of the Engine Compartment Access Panel, and remove the Panel

	Remove the bolt and spacer securing the engine oil level dipstick/filler tube, release the clip that secures the tube to the pipe, and remove the tube.
	Remove the 2 bolts that secure the expansion tank to the body, removing the tank from it's lower fixing, and set aside.
	Release the brake servo vacum pipe from the mainfold chamber.
	Release the ECU vacum hose from the manifold chamber.
	Release clip and hose of the EVAP cannister to inlet manifold chamber. A pair of long-nosed pliers are best for these types of clips.
	Release the throttle cable from the inlet mainfold chamber clip.
	Release the throttle cable from the abutment bracket.
	Release the inner cable from the throttle cam, by loosening the cable from around the cam and sliding the end cylinder out of the slot towards you.
	Release the fuel return hose from the fuel pressure regulator.
	Position a drainage tray to collect any coolant spillage, loosen the clip and disconnect the coolant hose from the inlet manifold.
	Disconnect the stepper motor multiplug.
	Release the 2 clips and 2 breather hoses from the camshaft cover.
	Some hoses are difficult to release, but once the clip is out of the way, it is possible to use the curved section of a pair of pliers to gentle grip the hose and rotate it gently until the 'seal' is broken. Do not over grip it or will be buying new hoses.
	Disconnect the injector harness multiplug. This and several other plus are held secure by small spring 'U' shaped clips which have to be pulled out by pliers before you can disconnect the plug. Not that there are several connectors like this, but not all the clips are the same size. If you push the clip back into place once the plug is disconnected, you will bnot mix them up later.
	Disconnect the throttle potentiometer multiplug.
	Disconnect the air intake temperature sensor multiplug. It's tucked away under the side of the mainfold.
	Disconnect the battery as a safety precaution - sparks and petrol do not mix well!. Postion an absorbant cloth to collect any fuel spillage, and loosen the fuel filter outlet union to relieve the fuel pressure. To prevent damage to the fuel system pipes and components, use two spanners when loosening or tightening the unions, one holding the larger nut from turning, whilst turning the smaller one.
	This is the awkward bit. You may need to use a mirror as shown in the next photograph. Undo the 2 bolts holding the fuel rail to the mainfold, and move the pipe out of the way.
	Remove the 3 nuts on the top edge of the manifold, and the 4 nuts underneath the manifold. The lower 4 nuts are directly below and in line with the four visible 'tubes' of the manifold. The only way you can see these is by using a suitable mirror, which in the photo is outlined in blue.
	Release the mainfold from the cylinder head studs and rotate it towards you to see the gasket.

Now gently prise out the gasket, but avoid using anything sharp that might scratch the seating or mainfold face. Then clean the seating.


Refitting

	While the mainfold is off, it is a good time to test and maybe clean the jiggle valve. This is simply a small ball that under normal conditions seals the pipe, but if air is present in the engine block, it no longer acts a seal and allows the air to escape up through the expansion tank. If mayo has been present, it can lead to the valve sticking and no longer allowing the escape of air.
	Ensure that the faces of the manifold and the engine block are clean and smooth. You should not have to use anything more that a petrol soaked cloth and a bit of elbow grease to clean the surfaces. Do not use anything that is likely to scratch the surfaces and prevent the new gasket from sealing.

Fit the new gasket.

Reposition the mainfold onto the engine block studs and push it home.

Refit the 7 nuts but do not tighten any until all are in place.

Then tighten in the sequence shown to 17 Nm.

Refit all other items in the reverse order.

Now refil with coolant and bleed the system thoroughly. For further details on refilling and bleeding the system, go to Coolant Refill and Bleed.