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Lead Fouling
Lead fouling can be difficult to diagnose. Although it usually appears as yellowish brown deposits on the insulator nose, some fuel additives may also cause similar discoloration (and are harmless). Also, a fouled plug can typically be detected with a simple resistance tester, whereas a lead fouled plug will read within specs (while at room temperature). Also, the ease of fouling will vary on different engines even with the same lead exposure; this is because lead compounds combine at different temperatures. Those formed at 370-470°C (700-790°F) having the greatest likelihood of causing lead resistance (fouling) on a plug. |