Do as whunter mentions, 55 ft. lbs. 27mm=1 1/16 inch deep socket, also check fuel lines, they can leak and it's hard to tell where from. If you do finally take it out, there is a heat shield, washer, what have you, that you will need to replace. Then you can take it to a shop for testing, but if you need the car, try to get a used one in it's place. Remember to change out washers every time you remove, and note their orientation. If you put them in upside down you'll have a leak. The only damage will be lower fuel mileage.

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83 SD

84 CD