CO levels and exhaust fumes
11-22-2006, 11:54 AM
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CO levels and exhaust fumes
I drove the 911 to VIR last weekend and decided to monitor interior CO levels. Previously on the way back from Summit Point with the windows closed I noticed some dizziness and decided to play it safe. I purchased CO/gas sensor and drove with the sensor sitting on the passenger seat. Generally with the windows closed, CO levels would rise to 33 to 45 ppm; although several times there were serious spikes one to 155 and another over 200 while at cruise speed. Simply lowering a window for a minute or less purged the cabin and brought the levels down to 0.
I have a relatively new stainless exhaust system and there appear to be no cracks in the system. I have run the car on a lift and checked for air leaks in the boxes. The headers do not sound like they are cracked; but, I am not sure that I would be able to detect the sound of leaks if they were contained in a heater box.
The engine is a 993 with 993 tin in an SC engine bay and there are plenty of sneak paths around the engine tin for the gasses to be drawn into the engine bay and sent forward through the heating system by the engine fan. The only reason this is showing up now is because I have wired the heater control valves in the full heat position (as opposed to full overboard).
I would like to know how the exhaust gas is getting in the cabin. It seems there could be a high concentration of exhaust gasses in the low pressure area below the Carrera tail and the seal around the engine lid is not very good. Are there any good ways to check for leaks?
I have a relatively new stainless exhaust system and there appear to be no cracks in the system. I have run the car on a lift and checked for air leaks in the boxes. The headers do not sound like they are cracked; but, I am not sure that I would be able to detect the sound of leaks if they were contained in a heater box.
The engine is a 993 with 993 tin in an SC engine bay and there are plenty of sneak paths around the engine tin for the gasses to be drawn into the engine bay and sent forward through the heating system by the engine fan. The only reason this is showing up now is because I have wired the heater control valves in the full heat position (as opposed to full overboard).
I would like to know how the exhaust gas is getting in the cabin. It seems there could be a high concentration of exhaust gasses in the low pressure area below the Carrera tail and the seal around the engine lid is not very good. Are there any good ways to check for leaks?
