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Replacing the coolant intermediate gasket.

Les Henson

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When this little gasket fails, the whole timing case has to be removed from the front of the engine in order to replace it. Specific to the 2.5 N/A, TD and 200TDi engines though. The 300TDi has a similar gasket known as the 'P' gasket, which is easier to replace and is covered in a seperate thread in the archive.

The vehicle is an ex-military 90 with the 2.5 N/A engine in.

The gasket is sandwiched between the rear timing case and the engine block, close to the alternator/manifolds, and behind the water pump. There are three bolts that pass through the water pump and timing case and into the block. These bolts are prone to seizing and snapping, so care is needed to undo them. This engine has had two snapped off in the past and has been bodged. I recently replaced the timing gear, and this has probably resulted in the gasket leaking. There's also a core plug adjacent to the gasket, and it's worth replacing it at at the same time. This is the sign that the intermediate gasket is leaking.


Drain the cooling system - bottom radiator hose is best, then remove top intake hose and top radiator hose.


Release the large circlip on the fan shroud.


The front of the shroud has three fixings, when undoing them, take care not to break the rubber mounts:-




Once the shroud is removed, there's plenty of room between the engine and radiator.


Water pump next - you need an angled 32mm water pump spanner. The thread is left hand, so undoes opposite to normal (clockwise).


Before removing the fan belt, use the tension of it to loosen the 4x13mm bolts that hold the pulley.


Remove the belt tensioner adjuster - retaining the spacer tube, push the alternator towards the engine block, remove the fan belt and then move the alternator away from the engine block, remove water pump pulley, and then undo both jubilee clips on the intermediate hose and slide the hose up until it clears the water pump.


The crankshaft bolt now has to be undone. The method I use is not recommended, but with care it is very easy and convenient. The torque of the starter motor is used to undo the bolt, which is very tight. A socket and breaker bar is locked against the underside of the chassis, and then the strater is turned briefly - the energy of which will undo the crank bolt. The engine mustn't start, so to prevent that from happening, the fuel cut-off solenoid wire has to be removed from the injector pump.


A good quality impact socket on a breaker bar.


The end of the bar is tight up against the underside of the chassis rail on the drivers side.


Close the bonnet and then briefly turn the ignition. There should be a sharp bang as the bolt breaks it's thread, and that should be sufficient for the bolt to be removed by hand or with a conventional ratchet.

With ant luck, the crank pulley will now slide off, sometimes they are stuck fast and some leverage or a puller is needed. Be careful not to damage the alloy timing cover.


Unbolt the water pump - keeping the bolts in order. Then the timing cover - again keeping the bolts in order.

You should now be looking at the timing gear.


Now put the engine in it's timing position. Rotate the crank until the marks on all three sprockets are in line with their respective marks .

Crank shaft:-


Injector pump and camshaft sprockets:-

Note the injector pump has two marks, use the dot and NOT the 'F'.


Remove the two bolts that hold the tensioner, then remove it along with the timing belt.


The crank sprocket is a slide fit, so carefullt lever it out of the crank front seal.


Prevent the injector pump sprocket from turning like this. Be careful not to damage the teeth of the sprocket.

The sprocket is on a taper fit and woodruff key. Lever the sprocket outwards with a screwdriver, and give it a sharp rap with a hammer and it should come away. The cam sprocket is removed in the same way.


Put the nut back on to prevent losing it.


The injector pump can be left in place without disconnecting the fuel supply and therefore avoiding having to bleed the bleeding system :P . The pump is held to the timing case by 3x13mm nuts and a bracket at the rear of the pump that's fixed to the block. The 4 injector pipes are steel and will help to keep it in place as well. The three nuts - the one between the engine block and pump is very awkward to get at.




Before removing them, make a mark that crosses from the injector pump body to the timing case. This is to ensure that the injector pump body goes back in the exact same position as before. A slight movement will affect the running of the engine.


The empty timing case - there are 7x 13mm bolts holding it to the engine block.


The front three sump bolts also have to be removed.


The case will now lift away. Bottom oil seal is crankshaft front oil seal, and the one at the top is the camshaft oil seal. On the right - the triangular gasket is for the injector pump. Best to replace these as part of the job.


This is the location of the intermediate gasket, the three holes are where the bolts pass through the pump etc


The bare engine block. Remove all traces of old gasket, and be careful the bits don't fall down into the sump. There's a gap at the front that will allow bits to fall into it.


The injector pump, held in place be the bracket at the rear, and the injector pipes.


There are two dowels that would hopefully stay in the engine block, but they are stuck in the timing case. Clean the gasket faces and I stuck the new gaskets to the case with some grease.


Strange little traingular gasket in the centre prevents oil from coming out through the studs that the belt tensioner is fixed to.


Injector pump gasket as well.


There's a core plug behind the cover. the minimal cost makes it worthwhile changing it at the same time.


Tap a sharp screwdriver through the plug and lever it out. The old and new side by side. Corrosion is nearly always from inside out.


Clean around the hole. What you see inside it is the cylinder liner.


Put a small amount of thread locking compound around the lip of the new seal and then use a 32mm socket to drift it in.


The cleaned timing case bolted back on.


Replace the sprockets and use thread locking compound on the injector pump nut.

The camshaft bolt has to have locking compound on the thread, and then a small amount of grease on the o-ring to prevent it bunching up as you tighten it.


Check that the sprockets are all in position, and then replace the belt and re-tension it. That's about it - a couple of things worth mentioning - The top radiator hose can rub against the fan shroud, which has a sharp edge. Make sure there's a small gap once the hose is fitted, as engine vibration will cause the pipe to be cut.


The top of the radiator has a curve in the pipe. The only flat area is at the end, so make sure the jubilee clip is out here, and not tucked under the rad mount.


Finally - cable tie the engine breather pipe to the intake top hose, just to keep it tidy.


If you are not sure if the timing belt and tensioner need replacing, then do it anyway, along with all the necessary gaskets and oil seals.

Les. :)

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