Toyota Avalon (1MZ) valve cover gasket replacement

One of the great things about the internet and the many people who use it is the whole sharing of knowledge thing. Like most people, I’ve probably consumed more info than I’ve provided, but every once in a while I like to make a modest contribution. This particular one is admittedly aimed at a niche audience, but so be it.

So, the story is, Bonnie’s dad gave me a job to do while he lives the good life on a cruise somewhere in northern Europe. The job was to replace the valve cover gaskets in his aging but still reliable 1998 Toyota Avalon. Apparently the gaskets are old enough that he’s getting a small oil leak through one of them… a common problem among these Toyota V6’s. I knew it was going to be a pain to get the valve cover off the rear bank of cylinders since you have to remove the intake manifold and a bunch of other stuff to even access the bolts. Then there’s this stupid !#$%^& wiring harness that is like the boss character at the end of a video game that you know you can beat but with no small amount of frustration. Anyway, perseverance paid off and I got the job done with only a little cursing and yelling. Thankfully, no permanent scarring (physical or mental.) Plus, amazingly enough, I didn’t have any leftover parts which is always a good sign. And the car started right back up after I put everything back together. Finally, I haven’t noticed any oil leaks (yet) so hopefully I did a good job. Sometimes it’s hard to tell with these slow leaks… for all I know, the leak is coming from somewhere else since I didn’t really notice as much oil as I would have expected from the old gaskets. Oh well… we’ll see.

So, back to the giving back part of this post… Here are some pictures I took along the way to make sure I knew how to put the darn thing back together correctly. There were so many hoses and electrical connections to keep track of. So for those of you who were too lazy to take these pictures yourself and now need a reference… enjoy! I also added some comments to the pictures that might be helpful for you.

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14 Responses to Toyota Avalon (1MZ) valve cover gasket replacement

  1. Sam says:

    Is that picture after cleaning or before cleaning,looks like brand new wit no sludge build up

  2. jason says:

    I didn’t have to do any cleaning really. The only thing I did was wipe the surface where the valve cover gasket goes.

  3. steve says:

    PLEASE, for the love of god, tell me how you got passed the wiring harness!

    Im at the fucking boss and I cant use any cheats 🙁

  4. jason says:

    Steve – Ahh, I remember the frustration like it was yesterday. One thing you can do is to wrap one of those ratcheting straps around the harness and something above you (like a conduit or pipe if you’re in your garage) and pull it up enough for you to have enough clearance. Having a friend help couldn’t hurt either. Otherwise, I just remember lots of scratches on my forearms and a sore back.

    I also remember thinking there’s no friggin’ way it was going to work. But it will. Perserverance will get you there. Good luck!

  5. steve says:

    Is it right to assume that I DONT need to disconnect all its connections to get it to move?

  6. jason says:

    I disconnected everything that I could. If I remember correctly, there was a section that was taped or clamped down that was doing most of the holding down.

  7. Chuck says:

    Jason,
    Nice job! Will you mine?

  8. jason says:

    Sure Chuck… but my rates are pretty prohibitive! 😉

  9. Corey says:

    Very informative and helpful post, especially the pictures. I was wondering if you could tell me how similar this job would be to a 1999 Avalon. I found one for sale with a leaky valve cover gasket. I’m tempted to try to get it for cheap and then make the repair myself. And advice would be greatly appreciated.

  10. jason says:

    I assume it would be the same… same engine and everything right?

  11. Al says:

    Jason – Awesome job with this! How long did this process take you?

  12. jason says:

    Jeesh, it was a while ago so I can’t remember for sure. It probably took the better part of a day. Maybe 6 hours?

  13. Tom says:

    Hey, would you recommend replacing any other parts, while you have it all apart?

  14. jason says:

    Not unless you see something worn.

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