I crawled underneath my 1990 F150 with the 302 and 5 speed today and found my O2 sensor. I have a couple of questions.

1) How do I pull the cables out of the sensor?

2) I have a small rear main seal leak that just happens to run down my O2 sensor cable. I'm not in a position to replace the seal right now, so should I replace the sensor now or later?

The reason I ask is that my gas mileage is about 7-9 mpg and I'm willing to bet its the stock sensor. At 146,000 miles - it had a stock fuel filter.

thanks
ken

 

There should be just a connector 5-10" away from the sensor to disconnect it. You need to buy or rent a special socket to remove it. Spray some penetrating lube on it for a few days, it'll be a toughy to get out.

 

The oil on the sensor won't hurt it - why do you even want to change it? It should come out easily with a 7/8" (I think) open-end wrench, but if it's stubborn, I prefer Liquid Wrench penetrating oil.