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question-tm.jpgMaybe you can answer this one for us as we’re pretty stumped: How does one reliably and cleanly remove the second temperature sensor plug on the side of the driver’s-side head on a Chevy small-block crate motor?  You know, the one with the 8mm square recess?  (We found a way around it, but we’d really like to find a better solution for next time.)

Some Chevys use both sensor ports, and some use just one or the other, so the crate motors ship with a plug in there.  Actually, if you’re trying to swap engines between different Chevys, you might run into the same issue needing to remove the plug to install a sensor.

The problem is that we can’t find anyone who makes an 8mm square drive socket or driver of any kind.  We’ve seen solutions online such as using RoboGrip pliers (didn’t work) or even driving in a (rare) 3/8″ to 5/16″ socket adapter (nope), but there’s got to be a clean way to do this.

Let us in on a good solution — or source for an 8mm square (not triple-square) driver — and we’ll drop you a tool from the pile in the mail.


12 Responses to Question: Have any experience with Chevy crate motors?

  1. Harry Zier says:

    If you’re looking for an 8mm squre male driver, why aren’t you using a pipe plug socket? you can get male and female versions from most of the tool truck guys in standard and metric sizes. Snap on lists them on page 111 of the version 800 catalog.
    You van also go to the kent moore catalog for the exact J tool. Hope this helps you.

  2. Kai says:

    See above – Snap-on seem to have a decent range on their website:

    Something like this?


  3. Kai says:

    If you’re looking for the female version, Snap-on don’t seem to have the 8mm on their website, however there is a 5/16″ unit that works out at 7.94mm, which I’m sure (with a little gentle persuasion) will fit =)

    [link removed because it doesn't work]

  4. Chuck Cage says:

    Harry/Kai: We did try a pipe plug socket, though the Snap-on truck only had the SAE (no metric), so we did the math and tried a 5/16″. It almost worked, but ended up marring the edges a bit.

    I suppose in the end the 8mm pipe plug socket may be the best answer. I’m going to ask the vendor to bring one next time, and we’ll see.

    I can’t believe that *no one* makes an 8mm square bit socket of some kind, though.

  5. PeterP says:

    Do you have a picture? I’ve never seen this, but I’m curious…

  6. Chris Ball says:

    I just checked my KBC catalogue (www.kbctools.com, page 787 in the new paper catalogue and p737 on-line) and it appears that 8mm square keystock is easy enough to buy, it even comes with gold dicromate plating to look sexy.

    I expect any machinery or steel supplier should be able to get it or have it kicking around since precision brand is pretty common. Once you have the correct size square making a tool out of it should be easy. Not quite a tool as such, but cheap.

  7. Jason says:

    So it has an 8mm square recess? Or an 8mm square head? Either way, I’d just get 8mm stock (either square stock for the former case, or 8mm I.D. tube stock for the latter), drill a hole through it, and press fit a round rod through the square stock for a handle. Maybe onlinemetals.com has such stock? Or smallparts.com?

  8. Chuck Cage says:

    Harry/Chris: I think the two of you have the best answer for this. I suspect that the correct 8mm pipe plug socket would have done the job for us if it hadn’t been a bit mangled already from other attempts. I’m pretty tempted to try your method, Chris, and build my own perfect tool for next time.

    If you two’ll drop me an email (using the Contact Us page) with your addresses, I’ll ship you out something from the pile.

  9. Jan says:

    Maybe a little late reaction but you might want to know that Peugeot and Citroen cars have an oil drain plug with the recessed 8 mm square. They have a simple L-shaped tool for that, with squares on both ends. I have done these oil changes scores of times and this tool might just be what you are looking for. I noticed this website because I am looking for an 8 mm square socket to remove a male plug!

  10. melvin says:

    If you can’t find the exact size of rod to fit the hole over sized square stock and a few minutes with a belt sander will get you a custom that’ll work. Use a tap wrench to turn your custom bit or a crescent if some torque is needed. HSS lathe cutters are an excellent donator if you need more than a one off.

  11. johnny t says:

    i went though this same problem recently. What i found to work the best is a large screwdriver with a square shank. One tap of a hammer, an opened end wrench on the shank of the screwdriver, and out it comes. Crude, but quick and effective. I also spent way too much time trying to track down the proper tool for this, of which GM seems to have under lock and key[secret stuff i guess].

  12. johnny t says:

    now i’m going to use the female i took out and weld it to a 3/8s socket extension, cause i came here looking for the male version……hhmmmm

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