Greg51

I bought my son a 87 3L 4WD V6 pathfinder. It has a worn out exhaust system.I'm not much of a mechanic, but my son and I are going to try and do the job ourselves. My question is, Should I change the catalytic converter while I'm at it? I don't know how to tell if one is bad. The other question. There is a sensor screwed in the pipe just pass the converter. The wire goes toward the hood, to the passenger side of the car, and plugs in. If that is the oxygen sensor,should I go ahead and change that also? The Pathfinder has well over 200,000 miles on it.

splatt

I highly recommend the Haynes manual. I am the original owner of a 1990 Pathfinder and have found it extremely useful.

I will try to help with your questions on the exhaust system.

I have never changed my catalytic converter, but have changed out the muffler and just recently replaced the gaskets from the catalytic converter forward and one of the exhaust manifolds.

1st, the manual says the catalytic converter has a limited working life and you'd need a CO tester to know if it was still reducing the emissions. They recommend taking it to a qualified shop or the dealer to have it checked. I have 165,000 miles on mine, so I'm sure it is shot but doesn't seem to affect the engine performance as far as I can tell.

2nd, as to your question on the sensor just ahead of the converter. The manual shows an "E.A.I. tube" but I can't find a reference to what that is. Sorry. I know it isn't the oxygen sensor though as that is attached to the exhaust manifold. It is probably the exhaust gas temperature sensor which the engine computer uses to monitor engine performance.

3rd, I learned through experience and talking to a mechanic that you will probably be better off paying the ridiculous $$ for a Nissan replacement muffler. On mine, it is one piece from the catalytic converter to the end of the tail pipe and I had to back the truck up ramps and then jack the rear end up further to have enough room to work it out over and under the frame and rear axle. If you have one built by Midas or someone there will be a good chance it will rattle against something somewhere.

4th, definitely change all the gaskets in the system while you have it apart.

Good luck. Your hardest part will probably be breaking loose some of the bolts on a vehicle that old.

Greg51

I want to thank you for your reply. I told my son that I didn't think it was the oxygen sensor. There is so much stuff around the manifold that I just can't see it. I'm going to follow your advise and get that book.