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Author Topic: HOW2: V6 Head Gasket Change - DO NOT REPLY  (Read 16841 times)

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JamesV6CDX

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HOW2: V6 Head Gasket Change - DO NOT REPLY
« on: 24 August 2007, 05:11:34 »

Vauxhall Omega V6 Cylinder Head Gasket change / Top end rebuild - © JamesV6CDX

PICTURES / DIAGRAMS PENDING.

Introduction

I will start by saying that Head Gasket failure is extremely rare on the V6 models due to the robust design of the engine. The symptoms often associated with head gasket failure on most engines, can be generated on the Omega’s by a range of other causes.

For example, over pressurising of the cooling system can be caused by blockages, or faulty Heater Bypass Valves, and oil in the coolant can be caused by failed Oil coolers.

I would recommend posting in the general help section with a comprehensive description of your cars symptoms, before condemning the head gasket(s).

This guide is aimed at DIY mechanics, who are competent with most aspects of working on their Omega. It is not a step by step guide detailing every little thing you will need to do, as I’ve assumed that if you’re taking on this task, you will at least have some experience of working on the V6 lump, or are competent with engines in general. It is to give you an IDEA only of what is involved in doing this DIY, and assumes some things you will have to work out as you go. This guide is based on a pre-facelift 2.5 or 3.0 V6 drive by cable engine. With very slight variations, the procedure is very similar for later 2.6 and 3.2 engines, just taking into account the Drive by wire and coil per plug additions.

If you are frightened at the thought of changing V6 head gaskets, It is really not an awful, or “specialist” job. If you are reasonably confident mechanically, then you will be able to take it on, and have a lot of fun in doing so. The key is to be very methodical in the way that you work, take your time, and label every single connector and vacuum pipe that you are not sure about, to avoid confusion or problems upon refitting. Never cut corners, and always make sure components are squeaky clean and dry before refitting.

Do not attempt to undertake this job for the first time, if you are up against the clock. If this is your first HG change on an Omega V6, I would recommend allowing 3+ days to complete the job in your own.

Tools required

Believe it or not, you will not need any particularly specialist tools to carry out this operation. A good automotive toolkit will be required, such as the Halfords 150pc set. You will need Female Torx sockets from E10 through to E14/E16, and Male Torx Tx50 for the camshaft pulleys, & Tx55 for the head bolts themselves.

You will also need a torque wrench with a range of 8 Newton meters upwards, and an angle measuring gauge.

Working environment / conditions

Very little working underneath the car is required for this job; however some is necessary (such as exhaust removal). Therefore it is important that the car is parked on level, firm ground. Obviously when working under the car especially, please observe all relevant safety precautions, never ever work solely supported by a jack.

It is beneficial if weather is bad to work inside, but you must have room to walk and work comfortably all around the vehicle, and have sufficient lighting.
This job can be undertaken completely by one person (I’ve done it on the drive) – however an additional pair of hands is extremely beneficial for certain tasks, especially removing and refitting the heads, which can be a little heavy with the exhausts manifolds fitted to them.



Removing the heads - The Guide

1)Pop the covering caps from both off the wiper arms, undo the 13mm retaining nuts, and remove the wiper arms. Remove the small screw on the drivers side, and remove the scuttle to allow better access to the rear of the engine.

2)Remove the battery terminals (usually 10mm). Remove the 13mm bolt holding the battery into the tray, and remove the battery.

3)Remove the two vacuum pipes from the vaccum tank on the bottom of the bagpipes, and also remove where one of these pipes splits off onto the front multiram.

4)Remove the Air temp sensor connection from near the air filter, also remove the Maf sensor plug, and the front multiram electrical plug. Undo the jubilee clips holding the bagpipes onto the throttle bodies and the air filter. Remove the bagpipes from the car. Remove the airbox from the car.

5)Remove the EGR valve electrical connection, and the RH knock sensor connection. Remove the connection from the rear of the Idle control valve on the passenger side of the plenum, and remove the valve from the car. Remove the rear multiram actuator connector, at the rear passenger side of the plenum. Also remove the vaccum pipe to the rear multiram. Remove the 4 breather pipes from the rear of the plenum. Remove the 2 bolts on the passenger side of the plenum, holding the cable tray to plenum.

6)Undo the 24mm nut holding the EGR “wiggly” pipe to the EGR valve on the drivers side of the plenum. Unplug the throttle position sensor on the front of the plenum.

7)Where fitted, remove the throttle cable and cruise control cable from the plenum.

« Last Edit: 27 August 2009, 08:43:10 by jimbob »
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JamesV6CDX

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Re: HOW2: V6 Head Gasket Change - DO NOT REPLY
« Reply #1 on: 24 August 2007, 05:12:39 »

8)Remove the 4 plenum bolt caps (if fitted). Using an E12 torx socket, remove the for plenum bolts. Carefully lift the plenum off and place clear of the vehicle, ensuring that you collect the 6 plenum O rings.

9)Place suitable rags / kitchen roll into the 6 inlet ports now exposed, (the “trumpets”) to prevent any foreign objects falling into the valves.

10)At the back of the inlet assembly, you will see a large electrical connector, connected to the injectors. Unplug this connector.

11)On the drivers side of the inlet, there will be two fuel unions – one feed, one return. Remove both of these using 17 and 19mm open ended spanners as appropriate. Tie them out of the way, facing upwards. Cover the ends of them to prevent the ingress of dirt etc (I find an old rubber glove works well).

12)Remove the six bolts holding the inlet assembly down, using an E12 torx socket on the end of a relatively long extension bar. Carefully remove the inlet assembly and injectors as one unit, and place clear of the car. Take extreme care not to damage the mating surfaces, or the injectors themselves.

13)You will now have exposed the remaining black plastic part of the inlet. This is held in with several bolts, which will need to be removed using an E12 Torx socket. Remove the black inlet, and position clear of the car. You have now completely exposed the “valley” or the “V” of the engine.

14)Remove the top passenger side coolant hose from the front coolant transfer pipe. This is usually held on with a sprung clip. Specific pliers are available for removing these, but I find a hefty pair of mole grips or plumbing grips works just as well. Once the coolant hose is removed, you must then remove the E10 retaining bolt for the coolant transfer pipe. This is usually best done with a slightly offset Torx spanner. Once this bolt is removed, pull the front coolant transfer pipe out of the thermostat housing. If it is stubborn, use a big pair of plumbing grips on the coolant transfer pipe, and twist it to and fro. It should become free. Whatever you do don’t use a hammer, or a levering device, as it is ali and can easily break.

15) Undo the two E10 bolts holding the thermostat housing onto the block. When refitting, this is an ideal opportunity to test/renew/reseal the thermostat.

16)Unplug the coolant temperature sensor and temperature gauge sender wire from the coolant bridge in the rear of the V. Undo the two 22mm unions holding the coolant bridge to the two cylinder heads. When undoing these bolts apply the pressure to the ratchet smoothly and evenly/progressively – NOT suddenly. These bolts can snap if removed in a heavy handed way. Once these bolts are removed, retrieve, and discard, the 4 x sealing washers. These will require renewal upon refitting.

17)Remove the secondary air injection and one way valve where fitted. This will be connected to the manifold pipes by means of small rubber pipe, remove the spring clips to remove these. There will be a 10mm and a 13mm retaining nut, one pipe on the top, and it will become free.

18)Slacken (but do not remove) the six bolts holding on the crank pulley, the three bolts holding on the water pump pulley, and the three bolts holding on the PAS pump pulley.


19)Familiarise yourself with the routing of the Auxiliary drive belt. Then remove the Auxiliary drive belt by turning the 15mm aux belt tensioner nut in a clockwise direction. This will release the tension from the belt, allowing it to be removed from its pulleys. Place the belt clear of the car.

20)Undo the two bolts holding the Aux belt tensioner assembly to the drivers side cylinder head. These will either be 15mm or T14, depending on age of car. Access should be easy now that the air box is removed.

21)Fully remove the water pump pulley, crankshaft pulley, and PAS pulley bolts. Remove the three respective pulleys, and place clear of the car.

22)Remove the front cable tray, using a suitable Allen key attachment on a short extension bar.

23)You are now in a position to remove the timing belt cover. Remove the 4 (sometimes 5 on later cars) bolts holding the outer cambelt cover on. Remove the cambelt cover from the engine.

24)Undo the three bolts holding on the water pump using an E12 socket, as this will hopefully be replaced as part of the rebuild!

25)Study the small toothed crank pulley at the bottom. You will see a “cut out” on the pulley. Using an E20 Torx socket, turn the engine clockwise only, until this cut-out is in the 4 o clock position. The engine is now at 60 degrees before top dead centre (TDC). This means that none of the pistons will be close to the tops of the valves, making valve/piston contact impossible, and hence reducing the risk of damage during disassembly.

26)Remove the cable tray that runs across the top of the passenger side cam-cover. Access in this area is a little tight, so this will enable you to position this part of the loom out of the way for better access.

27)Remove all of the plug (HT) leads from the spark plugs, and remove the other ends of the leads from the DIS pack on the rear of the LH cylinder head. Remove the leads from the car. Remove the DIS electrical connector.

28)Using an E10 socket remove both cam covers, to expose the camshafts. There will be ten bolts each side. When removing, be careful to retrieve all of the small O rings.
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Re: HOW2: V6 Head Gasket Change - DO NOT REPLY
« Reply #2 on: 24 August 2007, 05:13:57 »

29)Without moving the crank from 60deg BTDC, remove the cambelt kit, and remove the cambelt tensioner/top idler plate from the RH cylinder head.

30)Using a 24mm open ended spanner on the front of each camshaft, hold each of the cams firmly in place, whilst loosening their retaining bolts. Mark on the pulleys, which one is attached to which cam. Now fully remove the bolts, and place the cam sprockets clear of the vehicle.

31)Now remove the rear cambelt cover, by undoing the retaining bolts.

32)Now we remove the camshafts. Please note, it is VITALLY IMPORTANT, to record which cam bearing shell is in which position on the head. Due to the way they are manufactured, they must be refitted in their original positions. From memory, they are usually marked from L1 to L10 on the drivers side, and R1 to R10 on the passenger side.

33)Once you are confident you have recorded the correct position of each shell, work one camshaft at a time. Evenly and equally slacken all of the bolts, so the camshaft rises from it’s lifters equally. Remove all of the caps, and remove the camshafts from the heads. Please also note which camshaft is in which position (RH exhaust, RH inlet, LH inlet, LH exhaust). Due to the oil, don’t use stickers, tags with a bit of string is better).

34)Working from underneath the vehicle, unclip both oxygen sensor plugs, (to avoid strain) and remove each down pipe from its respective exhaust manifold. There will be 2 15mm nuts on each. I find a deep reach 15mm (spark plug) socket works well, on a long ½ drive extension bar. You will also need to remove the 13mm bolt securing the cats to the gearbox bracket, to allow you to remove the exhausts downwards. Position the exhausts down away from the manifolds.

35)Working at the back of the engine (from above) remove the 2 torx bolts holding the rear coolant transfer pipe onto the rear of the engine, and remove any other supporting bolts/brackets. Manoeuvre this transfer pipe out of the engine bay. It is necessary to remove this, so that the driver’s side exhaust manifold clears when the head is removed.

36)It is desirable that the followers are re-fitted in the order they were removed. Therefore, mark up 24 bags for the followers. Using a little suction device, or very carefully with a pair of long nosed pliers, remove the followers from the heads.

37)Slacken and remove all of the head bolts using a T55 socket, working from the inside out, one bank at a time.

38)You are now in a position to lift the heads off. With the aid of a helper, very carefully lift each cylinder head, with the manifold still attached. Remove and discard the used head gaskets from the block. If unharmed, retain the head gasket locating dowels for re-fitting, there should be two per bank.

Cylinder Head cleaning / checking

This process will need to be carried out on both cylinder heads:

1)First stage, is to remove the manifold (and dis pack in case of left hand side) from the head. Soak the nuts in plus gas prior to doing this. If any studs snap, it will be necessary to re-thread the holes.

2)Check that there is no warpage of the cylinder head.  Place a perfect straight edge across ALL angles you can think of across the head mating surface, and see if you can inset a feeler gauge, or see any discrepancies. If in ANY doubt, get it checked out by a machine shop. Skimming the V6 heads is best avoided if at all possible, a) because it will alter compression ratio, and b) because of the design of the V6, if there is a discrepancy in the amount skimmed off each head, the inlet may not be completely airtight, and cause problems.

3)Very thoroughly clean the mating surfaces of the head, both to the block, and exhaust manifold.

4)Flatten and clean the mating surface of the exhaust manifold using wet and dry paper.

5)Refit the exhaust manifolds. Always use a new genuine gasket, and preferably use new studs for refitting. Torque the studs evenly. If one stud is loose/broken, you WILL get an exhaust blow!

6)While the hydraulic followers are removed, take the opportunity to service them, using the excellent guide in this maintenance section by Marks DTM Calib.

7)Should you wish to progress and rebuild the head / fit new stem seals, see my guide to arrive shortly.

Guide to cylinder head refitting.


1) You may wish, while it is easily accessible, to re-seal the oil cooler plate. This will be covered shortly in another of my guides I am working on.

2) Thoroughly clean the cylinder block mating surfaces and remove any debris/fluid from the bores. Refit the head gasket locating dowels into the block, and position the head gaskets onto the block.

3) Lower the right hand head into place FIRST, and loosely fit all of the head bolts.

4) Refit the rear coolant transfer pipe to the block, using a new o-ring, and a small dab of sealant if you desire. (Helps keep O ring in place!)

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Re: HOW2: V6 Head Gasket Change - DO NOT REPLY
« Reply #3 on: 24 August 2007, 05:14:59 »

5) Fit the dis pack to the LH cylinder head, and lower the head onto the block. It is now necessary to tighten the head bolts to the manufacturers recommended torque and angle settings (found in the V6 torque values information, in Maintenance Guides). The head bolts must be tightened from the inside out – diagram to follow.

6) Now place your freshly serviced followers into their correct positions, and you are ready to re-fit the camshafts.

8)Rest the relevant camshafts in their correct positions in the heads, and fit their retaining shells into the correct positions (the ones you noted down during strip down!). Tighten them evenly and progressively, so the camshaft goes down onto the followers equally. Do this for each cam. Do not worry about hitting pistons, as the crank is in the 60deg BTDC position.

9)Fit the new camshaft oil seals, driving them in with a suitable drift.

10)Re-fit the rear timing belt cover.

11)Now we re-fit the cam pulleys. You will have marked which pulley went where upon removal. There are two keyways on each pair of pulleys, one set are marked 1 and 2, and the other 3 and 4. The 3 and 4 pulleys have a longer extension on them. The no1 keyway goes into on cam no1, furthest on drivers side, the no2 keyway into the next one along, and so forth. First loosely tighten, and then torque/angle tighten.

12)Using a small breaker bar (not a ratchet), move the cam pulleys into the correct positions for valve timing. The no 1,2,3,4 marks will be at the top respectively, aligned with the cut outs on the rear cambelt cover. Lock the pulleys using the cam locking tools.

13)Fit the new water pump, with new o-ring.

14)Now that the cams are locked in place, very slowly and carefully bring the crank around to TDC, and immediately lock in place using the water pump locking tool.

15)Fit a new timing belt kit, and time up the engine using the timing tools. Full instructions are included in the cambelt DVD here.

16)Fit the outer cambelt cover. Loosely fit the water pump pulley, PAS pump pulley, and crank pulley.

17)Fit the Aux belt tensioner.

18)Fit the aux belt, and tighten the bolts on the crank, PAS, and water pump pulleys.

19)Re-fit the secondary air injection valve assembly, and connect rubber pipes to manifold pipes.

20)Refit the coolant bridge, using new seals. Plug in the CTS and the temp gauge sender. Re-fit the thermostat and front transfer pipe, also using new o rings. Connect the coolant hose from the radiator to the coolant transfer pipe.

21)Refit new spark plugs, and refit the cam covers, using the useful procedure in maintenance guides. Remember to always use genuine GM gaskets and O rings, and only torque bolts to 8nm and in the correct sequence.

22)Refit the HT leads in the correct order and refit the LH cable tray.

23)Refit the inlet bridge / trumpets, preferably using new gaskets. Connect the injector multiplug back to the loom, and re-fit the fuel lines.

24)Refit the plenum, with 6 o rings, connecting all relevant breathers / cooling hoses / throttle and cruise cables / EGR valve and wiggly pipe.

25)Refit front cable tray and route cables appropriately.

26)Connect the ICV.

27)Once the cooling system is sealed, flush if desired, and refill with 50/50 antifreeze mix.

28)Refit the airbox, and refit the bagpipes. Connect all relevant electrical connectors and vac pipes at the front.

29)Drain the sump, and fill with fresh oil. Change oil filter.

30)Working underneath the car refit both exhaust downpipes with new gaskets, and secure bolts to gearbox brackets.

31)Refit the battery and secure it in it’s tray.

32)After a final check around the engine bay to check everything is connected fine, inc all fluid levels, you are now ready to attempt to start the engine. Make sure that the coolant header tank cap is Off, and the heater controls set to Hi. It may struggle to start initially because of lack of fuel in the injector rail, but should not take too much starting. The hydraulic lifters are likely to be noisy for up to ten minutes, this is normal following this sort of work.

33)When the engine is running, keep a VERY close eye on the temperature gauge, and do not let it overheat. Look closely for leaks etc, pay particular attention to anything dripping off the back of the bell housing under the car. Bear in mind that there will be lots of different bits of “smoke” – this is usually normal, and is a result of dirty fingerprints, etc on components. Feel around all hoses, and make sure they are getting warm, “burp” the hoses, to remove any potential air from the system. Once all is well in that dept fit the header tank cap. I would also recommend another oil change shortly after it’s been running for a while.
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