Core plug replacement

My elderly neighbour has a 2003 Ford Fiesta 1.4 three-door Durashift (automatic). Until recently, the car has performed well and been very reliable. The problem now is one you have covered in the past, with water settling in and around the number 4 spark plug. The screw core plug in the top of the head seems to be leaking. Do I have to go to Ford for a replacement and, if so, how difficult are they to remove and does the replacement need to be sealed in? Ian Macklin Replacing the core plug is normally quite straightforward. The core plug itself can be purchased from Ford for less than a couple of pounds.

To do the job, you first need to drain down the cooling system to below the level of the cylinderhead, then the plug leads and the cam cover have to be removed. Once the cam cover is off, you will have sufficient access to extract the old core plug by tapping a screwdriver down the edge and levering out the unit. It is advisable to cover the camshafts with a length of clean rag while carrying out the job, to prevent any debris from contaminating the area. When the old core plug is removed, the hole should be cleaned out and dried, to ensure there is no loose rust around the area.

It should not take a lot of effort to tap the new core plug into position. I normally smear a small amount of silicone sealant around the edge of the new plug, then use a socket to tap it into place. The top edge of the new core plug should sit flush with the edge of the cylinderhead as tapping it in too far will risk knocking it right through into the water jacket.

Be aware that the cam cover bolts and spark plug threads may be corroded if the coolant has been leaking for some time. heat shield that runs across the bulkhead to protect from the heat of the exhaust. There is no sign of any leak at the heater hose to matrix joints, which would be the most logical source.

The car was serviced last week by a local main dealer. It investigated the leak and is convinced it is coming from the heater matrix. They have estimated five hours labour plus parts to fix it. I am not convinced and don’t fancy a £600 bill. According to comments on the internet, a soggy carpet is the norm for a leaking matrix and the driver’s footwell on my car appears to be dry, but it is difficult to check.

I cannot see how coolant can get through a steel floor to appear where it does. The pool of coolant on the ground increases soon after the engine is started and allowed to idle. It gradually reduces in size over a few days of non-use and may even stop if left long enough. David Robb From your description, it does seem most likely that the matrix is the source of the leak. The normal place for the matrix to leak is from the joints to its end tanks. These are below the level of the connecting pipes from under the bonnet, so no signs would show at this point. The fact that you are smelling coolant in the vehicle also suggests the matrix is the source of the leak.

As yours is the Ghia model, I am assuming you also have air-conditioning. As the air-conditioning condenser is within the heater unit, it is fitted with a drain. This would allow the leaking coolant from the matrix to appear at the point you see it and not on the carpet.