Howto change a head gasket on a 12v 3ltr M103

[Ian B Walker]

When we did Paul's (JpsKiller) 3ltr Head Gasket we decided to do a howto. Its rather long so please be patient. I won't be able to complete the thread in one go as there are 40+ pictures and descriptions to go though.

In the beginning take one 3 ltr engine and notice the oil sprouting from just below the cylinder head.



This task is better done when you have access to vehicle ramps as it makes getting under the car that much easier.

First, disconnect the battery and put car in ramps. Make sure that the car is stable and safe to get under.

Drain the radiator, this is how we do it. Bit of garden hose and a bucket. The hose fits over the outlet peg by the radiator drain plug.

[Ian B Walker]

Go under the car armed with a very long extension bar and a 13mm socket and disconnect the exhaust pipes from the manifold.




Next disconnect the top hoses from the thermostat and the bottom heater hose from the lower radiator. Keep the jubilee clips. Also disconnect the Gear Box oil cooler pipes. Use a 17 and 19mm open ended spanner.

[jaymanek]

not working?

[Ian B Walker]

Disconnect the vacuum pipe using a 17 and 19mm pair of spanners



Now you can remove the clips from the radiator and fan shroud and lift the shroud up and move it backwards.




Next lift the radiator upwards and place in an safe area, you don't want to damage it.

[Ian B Walker]

We now have to remove the fan belt and fan. To do this you will need a 19mm socket. As per the pictures, slacken this nut but do not remove fully.




Then slacken off the 13mm nut on the tensioner (sorry picture is 90 degrees to the right) Once done pull upwards on the belt and remove from the pulley's.

[Ian B Walker]

Now we must remove the fan. Use a 5mm allen key to remove the three bolts securing it to the viscous coupling.



Store the fan vertically and out of the way.
Next to remove is the distributor cap and ignition leads. Once again your trusty 5mm allan key does this. There are three bolts that hold it on. The third one is hidden under the cover and above the pipe, just behind the bend in the pipe shown in the picture.

[Ian B Walker]

Once you have the ignition set out of the way we need to remove the rotor arm. Use a 3mm allen key and slacken the three bolts that secure it to the cam shaft. It is held on in a key way, so when you take it off remember not to try to twist it all the way round.



Next on the agenda is the cross pipe to the thermostat. The bolt on the thermostat is 10mm and the allen key (as shown) the trusty old 5mm allen key.




Take the two bolts out of this bracket (13mm) and move the bracket to the side (Belt tensioner damper)

[Ian B Walker]

We now need to take out the screw holding the transmission dipstick in place. This is a regular 6mm allen key. Then remove the rocker cover. This is held in place by 10mm bolts (12 of them)



Back to the front of the engine and remove the rotor arn carrier centre bolt, this is a torex screw



then remove the orange cover, if it has not already fallen off. You will be left with this.

[Ian B Walker]

We have already removed the belt tensioner damper, remember the 13mm bolts you unfastened? Ok so now on the other side of the top cover take out the other 13mm bolts. Tap the aluminium cover with a hide mallet and it will move forward.

[Ian B Walker]

The Great God Haynes (spit, cough, scratch parts of the anatomy) says to remove the head complete with the inlet manifold. If you want a hernia then ok follow those instructions. My way is to remove the inlet manifold from the head whilst it is in situ. Trick, fiddly? yes but will save you heart aches when you try to figure out where vac lines go. Part one is to free off the wiring harness. (three Allen screws, 5mm) Unplug all the connections (electrical) and the two vac pipes at the front of the engine. Important, remember which pegs they go on as one is at an angle. The next step is to remove the cold start valve, 5mm allen screws. This has a blue plug on it and is positioned in the centre of the inlet manifold.



Undo all the inlet manifold bolts (13mm) Some are rather tricky to get at. Now go under the car and unfasten the two support strut bolts (13mm)





Pull the inlet manifold off the engine and rescue the gasket and 2 positioning rings (you may find these stuck in the cylinder head , which is handy)

[Ian B Walker]

to be continued

[Ian B Walker]

The next task is to remove the chain tensioner. First with a 12mm hex socket remove the outer plug.



Once removed take out the spring that will become obvious, then with a 17mm hex socket remove the inner retainer (I use a piece of 17mm hex bar and a 17mm socket as shown)



Next remove the Electrical and Vacuum lines from the cylinder head. Also undo the Jubilee clips from the interconnecting pipe if you have not already done this. Note mark the Vacuum line positions.

[Ian B Walker]

Now the tricky bit . There is a pin holding the right hand chain guide that HAS to be removed. The pin is threaded. I use a small sliding hammer for this. You could use a bolt and washers / small socket, to pull it out but experience has taught me to use (in this case) the right tool.



Remove the cam sprocket and take off, support the chain (to stop it falling into the sump) with a bungie cord (shown in next pic). Remove the three 13mm bolts that hold down the oil spray tube. Take it off and store it carefully after cleaning.



Remove the cam shaft / rocker caps. Half a turn at a time in a diagonal pattern, untill no tension is left on the bolts. Be careful of the shims that sit between the arm and the valve stem, keep them in order as the caps. Lay them on a piece of cardboard and number them off for clarity. Now we have a bare cam waiting to be carefully lifted out and placed on the cardboard.

[Ian B Walker]

Everything from the head layed out



Using a large breaker bar and a 12mm spline socket, starting in the centre of the cylinder head, crack off the cylinder head bolts half a turn. Once cracked off remove the bolts and bin them. Always use new head bolts when refitting.



Mr Muscles at work

[Ian B Walker]

Forgot to mention, there is a thrust washer at the front of the cam, remove it and place is on the cardboard carefully, don't lose it.



Everything from the head layed out



Using a large breaker bar and a 12mm spline socket, starting in the centre of the cylinder head, crack off the cylinder head bolts half a turn. Once cracked off remove the bolts and bin them. Always use new head bolts when refitting.



Mr Muscles at work