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re-threading oil pressure sender on 3RZ-FE

Discussion in '1st Gen. Tacomas (1995-2004)' started by Old_Truck, Jun 23, 2019.

  1. Jun 23, 2019 at 5:40 PM
    #1
    Old_Truck

    Old_Truck [OP] Member

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    On a re-manufactured engine I'm installing I couldn't screw in my oil pressure sender. I think perhaps there was a little too much paint in the threads. It started a little, but very quickly got too tight.

    Then to make matters worse I tried screwing in the little adapter for my oil pressure gauge with the same threads. This went in tight, but unfortunately too tight and I wrenched it a bit, and when I pulled it out the threads were messed up a bit on the adapter.

    What I'd really like to do is run a chaser tap in the hole, but the threads are a funny size. Measuring the tapered threads on the oil pressure sender gives 10mm at the thickest part, and 0.9 thread pitch.

    [​IMG]

    So far I can't find a chaser tap for this. Any ideas on where to get a chaser tap?

    (BTW, I only have the old core for a couple more days before I have to ship it back, not that it's much help.)
     
  2. Jun 24, 2019 at 1:09 AM
    #2
    Wyoming09

    Wyoming09 Well-Known Member

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    Welcome !!

    I am guessing you have tried all the Industrial suppliers for a chaser tap with no luck

    Might be easier to drill and tap to a pipe thread then adapt to your gauge size
     
    robssol likes this.
  3. Jun 24, 2019 at 5:55 AM
    #3
    DrZ

    DrZ Well-Known Member

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    A quick google search found that Toyota used 1/8" BSPT (British Standard Pipe Thread) or possibly 1/8" NPT on some engines for the oil sender. So, you might try searching a little more to verify if this is correct, or head down to a local hardware store that might have a tap in BSPT sizes, or use a thread gauge to verify.

    And ask the remanufacturer why they didn't chases the threads! That happened to me once with the bolt hole on brake calipers I got from Pepboys.
     
  4. Jun 24, 2019 at 6:52 AM
    #4
    se7enine

    se7enine MCMLXXIX

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    Clean the sender and maybe hook up a small wire brush to a drill and clean the block's threads that way. I don't recall ever being able to thread the oil senders on very far before they got tight cause of the taper.
     
  5. Jun 24, 2019 at 3:31 PM
    #5
    pulldo

    pulldo Well-Known Member

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    The thread on the right is tapered pipe thread the one on the left is straight thread with a O-ring for sealing, the other seals on the threads,, with sealant on it of course. I didn't read all the replies so if this is a redundant answer, sorry, this just caught my eye.
     
  6. Jun 25, 2019 at 8:01 AM
    #6
    Old_Truck

    Old_Truck [OP] Member

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    I think you're right. This page also seems to confirm the dimensions. Thank you! Found the tap for $10+5 on amazon. Hope it works.
     
  7. Jul 29, 2019 at 7:16 AM
    #7
    Old Toyta Man

    Old Toyta Man New Member

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    Facing the same problem trying to install Gauge in place of the idiot light. Needing to adapt NPT to the tapered thread. Don't want to rethread as am afraid of cuttings getting into oil lubrication system.

    Any other suggestions???
     
  8. Jul 29, 2019 at 8:27 AM
    #8
    Old_Truck

    Old_Truck [OP] Member

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    I finally ended up with this solution:

    IMG_3009.jpg IMG_3012.jpg

    1) First I drilled out the hole bigger. This was to make the metal easier to bend later. I chucked this up on my small metal lathe which made this step easy. But you could also do this on a drill press.

    2) Then I purchased this narrow kerf hack saw. I had to look all over to find it. Using it I carefully hack sawed 4 slots across the top as you can see to provide releaf. Be careful not to saw too deeply, as you need to seal the oil in the threads that you don't cut. As it turned out I cut too deeply, and later had to resort to a O-ring at the base to do the sealing. This would only work short term on this hot engine area I think. .. unless you found a high temperature O-ring.

    3) Then I put the tip of the threads in an aluminum jawed vice and carefully squeezed the end of the threads, rotating a little at a time to generally taper the end. My adapter was a mild steel. Not sure how this will work on other parts.

    So once I was done with the modifications above, the once straight male threads would now easily screw into my tapered female hole.

    As it turned out my oil pressure on my newly re-manufactured engine was very good, even above factory specs. I suspect that in time it will come down a little as the engine breaks in.

    Hope this helps you. Good luck. At least if you screw up the first time you can try again with a new sender. Tapping out the engine hole was not something I decided I wanted to do, as it wouldn't allow me to back up if something didn't work and I got stuck.
     
    Old Toyta Man and cruiserguy like this.
  9. Jul 30, 2019 at 7:03 AM
    #9
    Old Toyta Man

    Old Toyta Man New Member

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    @Old_Truck

    That is really an elegant solution but More then I had time for.

    Turns out that O'Rileys stocks an adaptor that turns this thread into NPT and I just went that way.

    Thanks for your explicit photos and help. I sincerely appreciate it!
     
    DrZ likes this.
  10. Jul 30, 2019 at 9:05 AM
    #10
    Old_Truck

    Old_Truck [OP] Member

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    LOL, wish I'd known this earlier. Thanks! Here is similar, now that I know what to look for.
     
    Old Toyta Man likes this.

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