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 We had an email today from Mick asking if we could do a ‘how to’ on replacing a head gasket on the overhead cam six cylinder engines found in EA to EL Falcons. I did have a Falcon engine here up until a few weeks ago that would have been perfect to photograph each step but with room in the garage at a premium we decided to send it to the scrap heap so I will do my best with the limited pictures I have.

 First thing’s first, special tools required for the job.

• NEW SET OF HEAD BOLTS - DO NOT RE-USE THE HEADBOLTS. The head bolts used are what they call ‘torque to yield’ and basically stretch to a pre-determined length when first fitted and cannot be used again. We have had to replace more than one Falcon head gasket were someone had refitted the old bolts and you are lucky if it lasts more than a month or two with the old bolts put back in! Not a good result.
• A quality torque wrench.
• Torque angle gauge - not absolutely necessary but does help in tensioning the head bolts down correctly.
• 3mm long shaft allen key for releasing the timing chain tensioner or a small punch and hammer can be used to remove the tensioner retainer as a means of loosening the chain.

 

 

 

 

 

• A couple of plastic zip ties to secure the timing chain to the sprocket before removing the sprocket bolt. Yeah, see, they do come in handy!
• A permanent marker to number each spark plug lead as they are taken off, will save frustration later on.
• A variety of sockets, spanners, screwdrivers etc.

 I’ll run through each step in point form, I think that is easier for everyone to read.

• With the car away from the area that you will be working in, remove the bottom radiator hose at the radiator end and allow to drain.
• Move the car to your workspace.
• Remove the negative battery terminal.
• Remove the exhaust manifold. The heatshield needs to come off first and from memory I think all the bolts are 13mm. Check to see that there is sufficient clearance between the cylinder head and exhaust manifold to be able to remove the head. It may be necessary to loosen any clamps further down the on the exhaust system to achieve this clearance.
• Remove the accelerator cable. On single point injection engines it will be necessary to remove the air filter housing first.
• Now for the fun part! Remove all 10mm bolts that hold the intake manifold to the cylinder head and remove the bolts that hold the thermostat housing to the head. Particularly on Multi-Point engines this job can be a right royal pain in the backside. It may be necessary to jack the front of the car up and place it on chassis stands and remove some of the bolts from underneath. A 1/4 inch drive socket set comes in handy here also.
• Number and remove the spark plug leads. Bring them over to the intake side of the engine and let them sit on the intake manifold.
• Remove the PCV hose from the top of the tappet cover and the breather hose from the rear passengers side of the tappet cover.
• Remove the four 13mm bolts holding the tappet cover down.
• Remove the tappet cover from the engine. This can also be a little dicey, as the tappet cover comes up it will hit on the firewall and you need to angle it to get it out.
• Remove the power steering pump by removing the bolts that attach it to the cylinder head but keep the hoses attached and simply move it to the side of the engine bay out of the way.
• At this stage it would be wise to set the engine on to top dead centre, firing on number one. Rotate the crankshaft until the timing marks on the timing cover and the mark on the harmonic balancer line up. Check to see where the cam lobes of number one cylinder are facing. If they are facing down the engine is firing on number one. If they are facing up and close to the rocker arms you need to turn the engine another 180 degrees as it is firing on number six.

 

 

 

 

 

 

 

 

 

 

• Fit the plastic zip ties around the timing chain and through the holes in the sprocket to keep the timing lined up. Two or three zip ties will do the job. No, seriously!
• You will now be able to see the plug and retainer for the timing chain tensioner. There are two ways to loosen the tensioner, although the first way is the recommended one and the second is a way that I found I could do it without the necessary allen key. The first way is to remove the 13mm ‘plug’ and remove the filter that is inside the retainer with a piece of wire with a small hook in the end of it. Using the long shaft 3mm allen key, insert it through the tensioner plug hole, push and turn the tensioner cam sleeve clockwise until it locks. Ensure that the chain is now loose by pushing gently on the chain on the side that the tensioner is located to see if it is slack. If not, go back and repeat these steps.

 

 

 

 

 

 

 

 

 

• The second way is to loosen the retainer by using a small punch and hammer fitted into the holes in the retainer and once loose should be easily screwed out by hand. When using this method pressure needs to be kept on the tensioner down inside the timing case so that it doesn’t slip past the chain guide and fall into the sump. I use a long screwdriver and gently push the chain towards the drivers side of the car as the tensioner is coming out. Once the complete tensioner is out you can then use a 3mm allen key to lock it in the retracted position by pushing and turning in a clockwise direction.

 

 

 

 

 

 

 

 

• Remove the 10mm bolt that secures the upper part of the timing chain tensioner to the cylinder head. It is the bolt that you see at the front of the head.
• Insert a lever through one of the holes in the camshaft sprocket to stop it from moving and undo the sprocket retaining bolt.
• Remove the sprocket and chain from the camshaft (with zip ties still attached) and allow it to rest in the front of the cylinder head.
• Time to loosen the cylinder head bolts. The recommended sequence is in a spiral starting with the bolts at either end and working towards the middle. This sequence is important to follow to avoid warping the head as the bolts come undone.
• Once you have the bolts out throw them as far away as possible so you are not tempted to re-use them! Just kidding, putting them in the bin should do.
• Have someone help you remove the cylinder head from the engine.

 Assembly is basically the reverse of this procedure with attention paid to the following;

• Ensure all of the gasket surfaces are clean and all traces of the old gasket have been removed. I am a bit old school when it comes to this and prefer to use a single-sided razor blade over those flash air sanders. The abrasive pads on the sanders can tend to dig in a bit if you are not careful. Each to their own though!
• Ensure that the two locating dowels are positioned in the block and ensure that the replacement gasket lines up correctly with the coolant passages and oil galleries.
• The cork gasket that goes between the cylinder head and the timing cover needs to have plenty of sealant on both sides to avoid oil leaks. A silicone gasket maker such as Ultra Blue works well, but without it oil will leak from here in time.
• I also suggest using a non-hardening sealant such as Loctite No. 3 around the intake port holes on the intake manifold gasket and particularly on the thermostat housing to cylinder head gasket. The alloy is not real thick here and coolant seepage is common without a sealant being used.
• At the very least have the cylinder head checked for straightness and the surface machined if any irregularities are found.
• Lightly oil the threads and under the heads of the new cylinder head bolts before fitting. If available run the correct size tap down the threads in the block and blow out with compressed air.
• Tighten the head bolts to the specifications given on the gasket set. If in doubt ask the supplier, they should have this information for you.
• As a guide the torque setting is usually 40Nm for step one and then 90 degrees, in the sequence shown in the picture.

 

 

 

 

 

 

 

 

• When fitting the camshaft sprocket to the camshaft ensure that the locating pin on the camshaft sprocket engages with the slot in the camshaft.
• Once again use a lever through one of the camshaft sprocket holes to hold it secure while tightening the retaining bolt. The retaining bolt should be torqued to 50 Nm. DO NOT FORGET this step, I have seen the results of a camshaft sprocket retaining bolt left loose and it wasn’t pretty! Every valve bar two were bent.

 I think that just about covers it. If you any problems or queries about doing this job please send me an email to autofix@aapt.net.au and I will do my best to help you out.

Craig