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Removing a 300TDi cylinder head.

Les Henson

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No great mechanical skills needed to do this, you do need a torque wrench though if you plan to put the head back on. The cylinder head is alloy, so not a heavy great thing like the series and 2.5N/A and TD engines. It's relatively easy to remove the head and replace it. Taking what seems to be half the engine apart may appear daunting, but it takes less than two hours to remove it. Timing of the engine is not affected, nor are the electrics. The injector pipes have to be removed, and the glow plugs disconnected, but this is all minor stuff.

The engine in this thread is in a Disco that cooked the engine rather badly. The head has been removed to inspect engine damage, which is covered in a different thread.

If you are looking at the following pictures as a reference as you work on your own engine, then the radiator is out, top intercooler hose, top radiator hose, front heater hose, alternator wiring, the black engine cover, and other not necessarily associated other items have already been removed.

The reasons for removing the head can be varied - from replacing the head gasket, part of an engine rebuild, valve re-grind, Les Brock trying to get it right for the 3rd time :P .

Starting point. The engine is mostly complete as far as cylinder head removal is concerned.

Disconnect the battery.


Injector pipes first. They are fixed together in pairs - 1+2, 3+4. It's easier to remove 3+4 first as it then makes it easier to undo 1+2 where they are connected to the rear of the injector pump. Undo all 4 pipes where they connect to the injectors with a 17mm spanner. Take care not to snap the top of the injectors.

with the same size spanner, undo 3+4 and remove, then 1+2.

Once the pipes are removed, undo the two jubilee clips (6mm), and remove the two pipes from the oil seperator, and then undo the single 8mm bolt that holds the seperator to the side of the rocker cover. It's common for the seperator to leak, and as such is likely to be stuck on with RTV sealant. This is plastic, so be careful not to snap it.



Disconnect the power supply to the glow plugs (black cable), then remove the other 3x7mm nuts to remove the wiring loom for the glow plugs (yellow wire). Put the nuts and washers back on the glow plugs to prevent losing them.


Undo the two jubilee clips that hold the balance pipe and remove it completely. The spill rail pipe is melted in this picture, but normally you would undo the banjo bolt at it's end on the back of the injector pump (17mm). Put the bolt back in it's hole along with the two copper sealing washers.


Thermostat wire is at the front of the engine close to the thermostat housing funnily enough :D . Just pull it off.


Two heater supply hoses at the back/top of the engine. Undo the clips and bend/tie them out of the way.


Remove thermostat to water pump bypass pipe completely as well.


Now to the passenger side of the engine - the inlet manifold is only held by 2 x 10mm head bolts that have to be removed completely, and 2 x 13mm head nuts that only need to be undone a few turns.



The inlet manifold will just lift up off of the bottom studs.

Remove the rest of the nuts (15mm) that hold the exhaust manifold onto the head - 2 at the top with a spanner, one hidden in the gap between the turbo and manifold, and two at either end.



The steel portion of the heater hose is held onto the top of the head by two of the exhaust manifold nuts.


Once all the nuts and bolts have been removed, there's enough slack in the exhaust to move it away from the engine. Don't use any force, as the turbo oil feed and drain pipe is still connected.


The inlet manifold - two long 10mm head bolts through the top holes, and the two 13mm nuts that only have to be undone to allow it to be lifted off.


All that's now holding the head on the engine is 18 bolts. Four on the drivers side.


Nine close to the manifolds.


Undo the 3x13mm acorn nuts that hold the rocker cover on, and remove it. There are 5-more head bolts inside.


Rocker assembly next. This is held to the head by 3x13mm nuts that are on the same thread that the acorn nuts were on, then 2 x 10mm head bolts. Once these are removed, the whole assembly lifts off as one.


There are then 8 pushrods that have to be lifted out. If you don't plan to re-set the tappets, then keep these in the order they came out.


Head bolts now. All are 19mm and quite tight. A breaker bar is handy to undo them, or at least break them from their threads. There is a tightening sequence when fitting the bolts, and you should use the same sequence to undo each bolt 1/2 turn until they are loose enough to be removed easily. There are also three different sizes of bolt, and two different threads. If you think that the bolts have been over-stressed or damaged, then consider replacing them.


Two of the head bolts cannot be removed while the engine is still in the vehicle - the scuttle panel prevents this. You therefore need to secure them out of the block, and the easiets way is to lift them out to within 15mm of the panel, and then tie them as shown. The slight angle they are in prevents them from dropping back down.


The head is now free, and will lift off. If it doesn't, then a small a mount of leverage in a safe place will do the job.


Les. :)

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that is superb Les.

just a very quick, slightly related question, if i just want to remove my inlet manifold (to clean the marmite out of it) do i need to remove the exhaust manifold aswell, in order to fit a new gasket? as it looks like both manifolds share a common gasket....



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that is superb Les.

just a very quick, slightly related question, if i just want to remove my inlet manifold (to clean the marmite out of it) do i need to remove the exhaust manifold aswell, in order to fit a new gasket? as it looks like both manifolds share a common gasket....



When I did my head gasket a month back, I took the inlet & exhaust manifolds off and replaced common gasket. Some of the bolts are a pain to get at though.

My inlet manifold was supprisingly clean, with no build up in there.


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To remove just the inlet manifold - remove the top intercooler hose. Undo two 10mm head bolts that pass through the inlet manifold only. (as standard, these should be the only two 10mm head bolts on that side of the engine). Slacken the two 13mm nuts as shown in pics 9 and 10. The inlet manifold should lift out.

If the common gasket is in good condition still, then a very thin layer of RTV sealant or thread locking compound will make sure there's a good seal when you replace the manifold. Don't try to compensate for using the old gasket by over-tightening the nuts and bolts on re-assembly. You can just undo both inlet and exhaust manifold bolts - move the exhaust manifold away from the engine, and replace the gasket.

Les. :)

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I wouldn't bother trying to re-use a gasket. The damn things leak all the time anyway, so the chances are if its been on there for a while it's already leaking a bit (telltale sign is a stain down the side of the block underneath the manifolds) so hardly worth trying to re-use IMHO as you'll probably only end up doing the job again :)

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  • 7 years later...

Les, thanks for your time in writing this.

I'm pretty much geared up for this on my 300tdi, and plan to:

Remove head, send off to be skimmed and pressure tested (do I need to remove any other components for this?) They do this in 4 hours apparently. Existing gasket is 2 hole.

Order this: Turner Engineering 300TDI head fitting kit

Refit with a 3 hole gasket, although I will check with the engineers what they think would be best considering how much they skim?

Adjust valve clearances.

Fill and bleed the coolant system.

Have I missed anything?


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you will most likely need to strip the head, this isnt a particularly hard job but you will need a valve spring compressor to rebuild them after the head comes back (that is assuming that the company are only doing the skim, and not stripping/rebuilding the whole lot too.

i think all that is on the basic head, at this stage, is of course the valves, springs, retainers and collets, there are little caps which sit ontop of the valve stem which must be saved too (sometimes these wear through on engines where valve adjustment has been few and far between so might need replacement) the thermostat housing and gasket, the glowplugs and injectors, as much muck as you can remove yourself, and the valve stem seals.

i highly reccomend buying a pair of valve stem seal pliers as they make the job hassle free and you will avoid damaging the new valve stem seals.

of course there are a few things to be replaced as a matter of course during a head skim and rebuild. all gaskets you have taken off should be replaced, the rubber half moon type grommets in the front and back of the head where the rocker cover sits (assuming the TDI head has these i cant remember now) the valve stem seals are a common failiure (which is what makes an engine smoke oil for the first few mins of startup on 9/10 cases) and the injector sealing copper washers (ensure the old ones are definately removed from inside the head before fitting new ones obviously)

the valves would benefit from being lapped too.

ive probably missed something, i always do haha im sure someone more grown up will come along and let you know what i forgot to put


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P.S. do you have a 300TDi rebuild manual on PDF? this will contain clear instructions along with the correct torque settings and head bolt tighening sequence. plus it entails the process of deciding which gasket you use (0?, 1, 2, or 3 hole)

heres a link to the overhaul manual PDF

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stay with the same numbered hole gasket that was previously fitted, so if a 2 hole that's what you should be using after the head machining work, the piston protrusion will not change, just do not use a thinner gasket.

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I have always left the valves in the last 10 or so tdi heads I've had pressure tested and skimmed. Do you have an angle gauge and torque wrench capable of re fitting?


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I've skimmed more TDI heads than I care to remember. the Valves can stay in but the glow plugs and injectors have to come out... i've machined broken injectors out before now as well, that was a huge amount of fun. The thermostat housing wants removing as well. ( I use the hole for 1 of my clamps)

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