OIL WORRIES

I recently replaced the head gasket on my 1996 MGF 1.8 with a new multilayer gasket. While the head off I had it skimmed and re-built by a recommended garage, including fitting new valve stem oil seals.

The cam carrier was replaced using the provided sealant and after doing about 200km in the car I noticed a cloud of blue smoke out of the exhaust as I pulled up at home. On closer inspection I discovered oil in the throttle body and the spark plug from cylinder number one was sooty. Do you have any ideas what’s wrong?

David Robotham

The two most likely causes are that either the valve guide on one of the inlet valves is worn and even with the new seals, (which could have been damaged on installation) is allowing enough movement to allow the oil to run down and into the inlet manifold.

The other is that the breather system is the source of the unwanted oil entering the manifold. This may because of excess crankcase pressure due to failing piston rings, or it may be due problems with the breather pipes.

The first thing to check would be the integrity of the two breather hoses from the cam cover to the inlet manifold. If there are no problems with these then the wire wool filter in the cam cover should be checked to ensure it is in place and clean. If the wire gauze has failed, then this will allow oil to push through from the engine into the manifold.

If there are no problems with the breather system, then the possibility of a valve guide problem will need to be considered.