Fouled Spark Plugs

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Styria

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Sounds familiar ? Especially when applied to older cars going back to the fifties, sixties and perhaps even seventies, or when perhaps referring to the venerable M100 engine with its complex injection system. Of course, I understand that some owners and members may disagree and, of course if they do, they obviously have a well sorted injection system.

I readily recall any number of 6.3s that become somewhat 'cranky', and in one particular instance, when entrusting the appropriate tuning to a fully qualified mechanic and well familiar with the older Mercedes models, that the car would never run properly. He was too busy rush, rushing jobs to get them out of his workshop, with the result when the car was taken from him, it virtually refused to run cleanly. It really was desperation stakes and there seemed to be no solution in sight. The plugs were removed a couple of times and cleaned on a revolving brush, with not a lot of benefit, even though he was given complete freedom to perform any tasks necessary to get the car running right. In the end, the owner and myself took the car to a Service Station and fill up with fresh petrol. The owner was with me and I just got the idea that I should try new spark plugs, to which he was in agreement.

The difference was amazing. We had a car that was running almost perfectly, so obviously the condition of plugs needs to be right. However, 6.3s aren't always that happy to stay in tune, with the result that plugs, even when new, foul up easily. The other day, I had a four stroke mower that refused to start. It was the second time that this was happening, and pulling the plug and wire brushing showed no improvement in getting the mower to run. It was pretty dead alright, so out it came again. I then remembered a conversation I had with Michel probably a couple of months ago - and this related to the "cleaning" of the plugs as carried out by Jerry, his trusted spray painter. Using a gas flame, he would heat the inside of the plug and presumably burn out the petrol. To me, this was at least worth a try with the mower plug as I really did not feel like hiking it to a Spare Parts outlet. So, out came the small gas burner, heated up and installed the plug, and "Hey Presto", the thing started with the first pull. So, thanks to Jerry and Michel. Presently, I have just dished out the gas flame treatment to a set of 6.3 plugs, and it will be interesting to see if any improvement can be achieved. Certainly worth a try. Regards Styria
 

sean sherry

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With your two stroke engines plug fouling is the name of the game. Cleaning them often helps but the real cure is the rubbish bin....... They short out way up inside and defy cleaning.
 

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