I hope no one else has the same problem. Bit scary at the time but all now OK. The car is nearly 17 years old and the problem had not happened before so other owners probably should now worry. I think the problem may have happened due to a slight missfire at tickover that I have had for some time and could not find the reason for. It did not seem to be much of a problem in driving the car so I did not try too had to solve it. Some people suggested it may be a dodgy spark plug and others thought vacuum pipe leak. I changed the plugs and coils on the right hand bank ( the ones that are easy to get at) with no effect and decided that the left hand ones under the inlet manifold would be too difficult and probably would not cure the missfire so left them. MISTAKE! I have now had to take the manifold off to sort out the fire and found that it is not that difficul a job. ( Remove the windscreen wipers, the plastic panel and the suspension brace and then 11 bolts, 6 multipin connectors and 6 hoses then lift off ). I also changed the plugs and coils on the left side while I had it dismantled and now find that I have cured the missfire. It probably was caused by a dodgy plug.
My thoughts now are that the missfire caused more vibration of the engine than normal and this meant that the wires to the camshaft position sensor were shaken so that hey moved up to touch the underside of the manifold and the vibrations wore through the insulation and caused the fire. Just goes to show that you should sort out what appear to be minor problems before they become much bigger ones
I hope this reassures other Mark 1 S-type owners, and that this was a hopefully unique occurance.
Have a happy christmas.
Ges
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