NISSAN Pictures of how I replaced the exhaust manifold, (and PASSED CA SMOG!!) on my 87-95 Nissan Pathfinder.

I was super bummed. The old girl failed smog. She failed the super strict California smog test. O2, and CO are fine. The HC, hydrocarbons, are too high.
Heat Shields

  • I searched forums and even read some books. A book. I skimmed part of a chapter. My bet is that an exhaust leak lets oxygen into the exhaust. This makes the oxygen sensor think the mix is lean (too much oxygen), so the O2 sensor tells the computer to add extra fuel to compensate. The catalytic converter takes care of the oxygen that got in from the leak, but there is still extra fuel, HC, left over. She smells like fuel and gets lousy gas mileage. And Pathfinders commonly break exhaust manifold studs and get manifold cracks. Also I can hear the exhaust leak.
    Hold on to your wallet. Here we go.
    But first, lets pay some bills:

    1. It sounds like the right exhaust manifold, so let's take a look. To see anything I gotta get the heat shield off. So WD-40
      failed smog

    2. Heat Shields. Six bolts, three high and three low through the wheel well.
      Heat Shields

    3. That was difficult. Two bolts moves the fuel filter out of the way. This fuel filter holder just unclips and I can set that aside.
      fuel filter

    4. Those areas on the left and right stained light look like leaks. Light looks likes leaks. Also in this picture I have a mirror under the manifold so I can look under to see the nuts. Phrasing.

    5. I took off the nuts in the reverse order of this picture. Basically that is outside to inside.
      nuts in order

    6. Each nut has a thick washer behind it. The washers are not magnetic. What are they made of? Copper? Magnet on a stick did not help me retrieve these when I inevitably dropped them.

    7. Then I get to crawl under the car and remove the nuts from the manifold to down pipe connection. So easy and not eyes full of dirt and laying in a pile of greasy dust at all.
      manifold to downpipe

    8. Now this will be so easy to remove. I just wiggle this. Maybe if I pull from this side. I just have to get this angle. DAMN IT!

    9. Downpipe removed.

    10. There's the old manifold and the new one. Looks like there is another leak here on the underside. This is a manifold, not a header. Manifolds are rough thick cast iron. Headers are smooth welded steel tubing. Just found that out.

    11. Here are the exhaust ports, valves inside. Should they be white like that? Running rich means they should be black, no? For a spark plug that is true. Maybe exhaust valves get hotter than a spark plug. Again, looking back up with a mirror.
      exhaust valves

    12. Header studs need to be installed.
      manifold studs

    13. Header studs installed. I think I was supposed to use thread locker. But I used anti sieze absolutely everywhere. When in doubt, I get the WD-40 and anti sieze.
      manifold studs

    14. Here's the old gasket and the new one. The kit manifold came with two new gaskets. One with with a thin edge on one side or the one with the sides of uniform thickness. The old gasket broke into pieces, but I reconstructed it to compare. Looks like I will use the uniform thickness.

    15. FSM says tighten bolts in this order and to 13-16 ft lbs.
      service manual

    16. Some of the studs came out with the nut, so I put anti sieze on them too. Love that anti sieze. I do not know if I am supposed to use this or not. I am just guessing. The FSM did not say anything about it.

    17. There's the new manifold installed.
      manifold installed

    18. There are new gaskets on the down pipe.

    19. This is the new gasket for the downpipe to the catalytic converter flange. This is the old gasket that I put in when I did the transmission. This gasket does not look like the original. This gasket has that extra layer circle in the center. That extra layer makes the flange bend when I tighten the nuts on the flange. I installed it and started the engine, and I could feel the exhaust puffing out the sides of the flange.

    20. So I ripped out the center cirle and the metal ring from the new gasket. Then I bent the exhaust pipe flange straight(er) with an adjustable wrench. Then I got some exhaust cement paste and slathered it all over the new modified gasket. I also got it in my hair and on my face, and that's bad. M'kay.

    21. Then I installed it, tightened it up, let it dry overnight, and...

    22. Passed that smog test, bitch! YEAH!
      smog test

    23. Next I sold out to make 02ยข so I can fulfill my lifelong dream of owning a 1986 944 with blown head gaskets.

      But no minivans!

    24. Then I finished my beer.

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    Think: Cars are expensive, powerful, and heavy.   Before I start work, I face the possibility that I will destroy my vehicle, my own life, and innocent pedestrians' lives.   If anyone messes with a 4000 lb machine capable of 100 mph, these are real possibilities.   If I get in over my head, I call a professional mechanic.   The information on this website is provided only for entertainment purposes, and it is not intended as advice on how to service a vehicle.   For all you know I made this up.   Don`t believe everything you read on the internet.

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