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Cooked condenser - a tale of overheating

When I was doing my preparations for the run to the Pyrenees and Le Mans I was careful to write a list of all that was to be done to the car prior to setting off. Kingpins to grease, oil and filter, points, plugs, condenser, valve clearances etc. but I left out a critical item.

I was bowling along having covered 3000 miles since finishing the car , enjoying the French country roads. Suddenly I heard a warning cough from the engine. It didn't repeat itself so I carried on driving with a weather-ear cocked.

Claude Laubret in his lovely Pembleton

Click to enlarge

The following day I set off again and had covered a further 100 miles when the cough recurred. This time a little more intrusively. There was also a noticeable increase in the tail-gunner syndrome on the overrun. It sounded like fuel starvation but I had filled up and put in octane booster. Was there a vacuum in the tank? I reached behind to release the filler, no difference. The motor spluttered and recovered and I stopped to investigate. No sign of anything untoward so after a few minutes I carried on. Another 10 miles and the cough repeated more insistently, this time causing a hasty pull-over. I went through everything again but could find no fault. Panic, there I am at the side of the road in a foreign country and no idea! Fortunately I had Claude's number so I called and spoke to his daughter and eventually to Claude himself. A very reassuring voice told me we could fix it and he would be there with his trailer ‘tout a l'heure'

I waited and worried and when the engine had cooled down I took out the plugs and cleaned them for want of something better to do. When they were re-fitted it fired up so I set off again towards Claude. A further 10 miles and it died again, on the outskirts of Orleans. This time I waited and when he arrived we tried it again; it ran so I decided to follow his trailer. It ran perfectly until we were a mile or so from his home and it died again. In the workshop we narrowed the investigation to fuel starvation and took out the petrol filter. It was filthy! Problem solved, a new filter and a tickle on the carbs and it was away. Sorted.

The following day I set off again and drove 30miles and stopped for fuel. Filled up and away but it died again within a few hundred yards of the pumps. I call Claude and set off back the way I came until we met. A bit of road side fiddling and it was fine for a couple of miles and then that was it. No spark.

Back at Claude's and the front cover came off to show us a melted condenser, black ‘liquorice' dripping from the end of it and the insulating plug melted to the point that the terminal it carries shorted on the bean-can. A replacement from my stache of spares and it was like a new motor! The carbs were re-set to their original settings. We came to the conclusion that the effect of a blocked fuel filter had been to make the mixture very weak, causing the back-firing on the overrun and,in the extremely hot weather,overheating the engine to the extent that the plastics in the condenser and its terminal insulator melted.

I can't stress enough how reassuring it was to have a contact in such an emergency and how grateful I am to Claude for all his help. He gave up the best part of his weekend to help out a fellow Pembletoniste and he and his family made me most welcome. Moral: change the fuel filter at every service.

Lea Thermallet.


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