Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 2 months ago

2008 Honda Civic 1.8l (r18a) passenger side motor mount bolt thread size?

Replaced my passenger side motor mount but one of the bolts that go into the block pulled the threads with it. I circled the one I’m talking about in the picture, I’ve only seen one person say it’s a m12x1.25 but it’s nowhere close to that. It’s closest to a m14x1.5. Does anyone know what the actual thread size is so I can drill/tap and go the next size up ? 

(Picture taken before motor mount replacement, just for reference)

Attachment image

4 Answers

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  • Anonymous
    2 months ago

    Take a Comparable bolt from another MM, take it to hardware store. An SAE bolt the next size and tap are cheaper. Get a Grade 8 SAE;  or an  8.8 Metric if you wanna stay kosher.

      Thread pitch matters little unless you want to try to tap hole with same pitch. It might Not  be possible, often bigger bolts have a Different pitch. Go for a coarse thread in either case.

      Unless you ask for a Helicoil  kit; these are $$ but don't require different bolts/threads nor re-drilling.

      If block  is Cast Iron, Go Slow, use Plenty  of oil. Reverse tap  every 1/4 turn,  then proceed CW  another 1/4 turn, repeat..   Drill the hole out, First,  to recc. size for the  bolt  and material. Go  for 50% threads. (75% if Aluminum.). Use a bottoming or plug tap.

    https://www.bestmaterials.com/images/Thread_Drill_...

    https://littlemachineshop.com/images/gallery/PDF/T...

      When the Chrysler stripped a screw that held the timing belt tensioner on (went into an Aluminum casting), the very next size was SAE. I already had the tap, just 79 cents for screw and lock washer. I spray painted its head RED so next guy  would realize it was different than the other  screw. (oil Probably washed the paint off, anyway..)

  • 2 months ago

    Take the bolt to a hardware store and have them measure for a next size up tap. Get a replacement bolt that is grade 8.

  • 2 months ago

    Take one of the other bolts to the hardware store to size up a larger diameter bolt. The thread pitch doesn't matter...just the length. It doesn't even matter if it's metric since you'll be tapping the hole anyway. You'll need to drill a hole in the mount and the motor before threading the hole for the bolt. After looking at the bolt you have circled If I remember correctly you might be able to just drill all the way through that part and install a longer bolt with a lock nut.

  • Anonymous
    2 months ago

    Typical Honda. Snapped two bolts way too easily on my stepdaughters 2004 Civic. Was so surprised, last Honda I worked on was 1977 Accord and that was a solid machine.

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