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300TDI p gasket

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A reasonably common problem with the 300TDi engine is failure of the 'P' Gasket. Name kind-of describes it perfectly. The gasket is sandwiched between the top of the block at the front of the engine and the alloy casting that supports the alternator, PAS pump, and water pump. There's a core plug right next to the gasket, so there's a chance this may have failed. Getting at both is the same method, and parts are very cheap. You need to remove 3 x bolts that also secure the water pump, so it's wise to replace that gasket at the same time - sods law being what it is, this will leak if you just replace the bolts with the old gasket.

Signs of the gasket (or core plug) leaking.

Dipstick tube is to the right.




Top/front of the engine.


Take off the oil filler cap, remove the black engine top cover, then replace the oil filler cap.

Remove also:-

Intercooler top hose

Radiator top hose

Thermostat/water pump pipe

Disconnect bottom hose where it connects to the water pump, plus the heater hose that branches off it.

While the belt is still on - slacken the 3 x 10mm head bolts that holds the pulley wheel to both the water pump and PAS pump. Belt tension will keep the pulleys still while you do this.

Using a 15mm spanner - lever the belt tensioner to the left and remove the belt from all pulleys on the passeneger side of the engine.

Then undo the centre nut of the tensioner and remove the whole thing. The stud came off with the nut, which actually makes access a bit easier, but it's not that important if just the nut comes off.



The thermostat housing elbow has to come off too. The seal is a rubber ring, and removing two 10mm head bolts will release it.

Alternator next - 1 x 10mm head bolt at the bottom, then one very long 10mm head bolt and 13mm nut at the top.


Once free, the alternator can be laid out of the way with the wires still attached.


Remove both water pump wheel and PAS pump wheel. It should look like this now.


Unbolt the water pump - these three bolts pass right through the alloy housing, through the 'P' gasket, and into the block. They corrode and are very tight. Be careful you don't break them. If the heads round off, then hammer a 3/8" socket on and try again.


Unbolt the bracket that holds the PAS pump, and let it sit down out of the way with the pipes still connected.

Just the alloy casing to remove now - 1 10mm head bolt goes into the block, and another 10mm head bolt passes through the edge of the engine block and has a 13mm nut on the end.



One 13mm nut is behind where the belt tensioner was.


The alloy casting will now lift away, exposing the leaky gasket. The core plug I mentioned earlier is here. If you have any doubt as to it's condition, it might be wise to replace it anyway while you are there. The plug is very cheap, and replacing it now will possibly save you greif in the future.


This is the alloy casting you just removed, you can plainly see where the gasket had been leaking at the top (black area)


Carefully clean the mating faces, and even though I am using a new gasket I have still used a small amount of sealant either side of it, just to be on the safe side.

New water pump gasket too, then re-assemble. The correct amount of anti-freeze back in the system, and that should be the job finished.

The three bolts that pass through the pump, casting, 'P' gasket, and into the block will be very rusty. Clean them with a wire brush and coat with copperslip grease or similar.

Once the belt is back on - use it's tension to tighten the bolts for the two pulleys.

Les. :)

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