Why replace gaskets in engine

Part Finder. Select Language. Signs of a Blown Head Gasket. Message Regarding Your Privacy. I accept Submit Submit. What does a head gasket do? Bad head gasket symptoms Because the cylinder head gasket seals coolant passages, a blown head gasket will allow coolant to enter the cylinders. How can I prevent a blown head gasket? Back Back to Gaskets Related Stories. Step 2: Check the head and block for flatness. A machined straight edge across the surface and feeler gauge will reveal all.

The service manual will provide specifications. Blocks or heads out of specification must be sent out to the machine shop and be repaired. The machine shop will also be able to check for cracks. Step 3: Prepare the surface. Never use anything that will remove metal. Be careful not to scratch the deck of the block or mounting surface of the head. While it may seem like a good idea to use a scrubber pad connected to a power tool, the surface irregularities created can cause sealing problems down the road.

Step 4: Chase the head bolt or stud holes with a tap or thread chaser to remove any crud and prepare the threads. Use compressed air to blow out any stragglers. Correct head bolt torque is of the utmost importance.

Any interference can throw off the torque readings. Step 5: Prefit the head gasket in the correct orientation. Never use sealant unless specifically required by the manufacturer. Head gaskets that require sealant will usually come so equipped. The service manual will outline sealant locations and requirements. Step 6: Correct bolt tightening sequence and torque is key to proper head gasket sealing. Slacken the alternator or dynamo adjuster and pivot bolts, push the unit inwards and ease off the drive belt.

Remove the belt completely. Remove the radiator See How to remove a car radiator if necessary, to make room for removing the crankshaft pulley. If the car has a manual gearbox , select first or reverse gear and put the handbrake full on. Otherwise, disconnect the battery and remove the starter motor. Insert a tyre lever or large screwdriver into the starter aperture so that it jams in the teeth of the ring gear on the flywheel.

Unscrew the pulley bolt anticlockwise with a socket and bar. Start it turning with a sharp blow on the bar. On engines that rotate anti clockwise viewed from the front the pulley bolt unscrews clockwise. The pulley is kept from turning on the crankshaft by a key fitting into grooves on the crankshaft and pulley. Thoroughly clean the area around the oil seal and check how it is fitted. If you cannot see the outer end of the seal, remove the timing-belt cover or chain cover not the belt or chain and possibly the water pump See Replacing a water pump to reveal it.

On an engine with a belt-driven overhead camshaft , remove the belt and its drive sprocket. Clean all dirt and oil from the housing, and set the new seal in place with its open spring side towards the engine. Put a wooden block or a piece of large tube against the seal and gently tap it squarely into the housing until it is fully home.

Refit the timing cover, if removed. Thoroughly clean the sleeve at the back of the pulley, and look for any roughness on it where it touches the seal.

If necessary, smooth it with fine wet-and-dry abrasive paper. Smear clean engine oil on the pulley sleeve and seal, then refit the pulley with the key and keyway aligned. Tighten the bolt to the correct torque consult a service manual or a dealer if in doubt. Remove the distributor cap. Before removing the distributor See Removing and refitting the distributor , mark the position of the rotor arm so that you can refit it just as it was.

To do this, turn the engine with a socket on the crankshaft pulley bolt until the rotor arm is pointing to the plug contact of the timing cylinder usually No. Mark the position of the rotor arm by lightly scratching a line on the distributor body. Disconnect the LT lead from the distributor body.

Loosen the securing-clamp bolt at the base of the distributor, then carefully withdraw the distributor. If the drive gear has slanting teeth, they may cause the rotor arm to turn. If it does, mark its new position to aid refitting. There may be a rubber '0' ring oil seal round the base of the distributor, or a paper gasket under the plate of the securing clamp.

Remove either seal, clean away all dirt and oil, and fit the new one. Refit the distributor, ensuring that the rotor arm is exactly in line with the first mark. If not, withdraw the distributor and try again. The Video Course teaches you everything about modern cars.

Lift off the cloth, making sure no debris falls into the valve gear. Fit the new gasket to the cover or head — whichever the old gasket was fixed to. Refit all pipes and wires, and the air cleaner. Start the engine and check for oil leaks. Make sure the fuel-pipe connections are clean. Unplug them and reconnect to the pump. Once the engine is securely held, lower and remove the jack. Loosen all the sump nuts or bolts with a socket, long extension bar and ratchet handle. On some engines you have to remove the clutch-housing cover to reach the rear nuts.

Remove most of the fixings, then support the sump with one hand while you take out the last few. Carefully lower the sump from the crankcase. Lay out the pieces of the new gasket on clean newspaper, and note how the joints fit.

The mating surfaces of the head or block must be perfectly clean, flat and smooth. Lift out the rags without dropping dirt into the engine, bores or passages. Repeat with the ruler laid diagonally between the other two comers. Wipe the head and block absolutely clean with a cloth moistened with petrol. On most cars you need to remove several parts to get at the seal.

The pulley may slide off easily; if not, use a universal puller, which you may be able to hire. Remove the key and keep it safe until ready to refit the pulley. Lever the seal out with a screwdriver, working carefully to avoid scoring the seal housing. Refit all the components in the reverse order of dismantling. If it does, mark its new position to aid refitting Some distributors can be removed without separating the gears, and so the arm does not turn.