have 12mm head bolts, BGB says they're supposed to be 10mm??

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have 12mm head bolts, BGB says they're supposed to be 10mm??

Postby turboyoda » Sat Oct 31, 2009 1:47 am

So i ordered a 10mm triple square bit (12 point) from sears ahead of time because the BGB called for it to remove the head bolts. Assumed i could just remove my head bolts :D . wrong :( . It was too small. The 12mm bit i just got (also from sears) fits right and i'm removing the head tomorrow.

My question: did toyota later produce a 12mm version of these head bolts? or are these likely some sort of aftermarket bolts? or did the BGB pull a fast one on me? :shoots:

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Postby Shaggz00 » Sat Oct 31, 2009 1:37 pm

I doubt toyota would use 10mm bolts in such a location based on torque specs alone. Somebody correct me if I'm wrong, I thought the stock bolts were hex bolts...
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Postby turboyoda » Sat Oct 31, 2009 3:00 pm

triple square is the terminology gearwrench by sears uses for a 12-point hex bit. i guess they could've said double hex too :shrug: . The point being that i have a 12mm 12-point hex bit that fits perfectly inside the head bolts. Both the 90 and 93 BGBs specifically say the sst for head bolt removal is "Hexagon 10mm wrench."

As for the torque specs, the BGB calls for only 36 ft-lbs on the stock bolts. And since these bolts are driven by a bit, i would guess the bolt thickness to be bigger than a standard 10mm bolt.

The BGB also pictures the head bolts being the type you would put a socket over, which mine are not, and that coupled with the picture of the head bolt removal tool being a bit, i don't know what to think that i have here :( .
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Postby Shaggz00 » Sun Nov 01, 2009 2:43 pm

pictures?
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Postby turboyoda » Mon Nov 02, 2009 10:22 pm

best photo i could find/make in five minutes. like i said the bgb says it's supposed to be a 10mm bolt. And a lot of other posts i've found also say that's what they had. i'm just trying to figure out why this is 12mm and not 10mm. Thanks for you help shaggz.

Image

EDIT: misplaced/confusing comma
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Postby turboyoda » Sat Nov 07, 2009 4:47 am

No one? Hmm. i'm just gonna assume they are some sort of ebay special until i find out otherwise. :|
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Postby ___Scott___ » Sat Nov 07, 2009 5:03 am

The bolt size refers to the diameter of the shank of the bolt, not the size of tool used to turn it.
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Postby turboyoda » Sat Nov 07, 2009 6:40 pm

really? then this just got more confusing to me. You're saying the head bolt is called 10mm because the shank is 10mm and there's no indication of what size bit fits it? So a 10mm bolt can have a 12mm head. That sounds to me like an engineering standard reather than a technicians standard. Either way the bgb lists...

Image

am i complicating this somehow?
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Postby Shaggz00 » Sat Nov 07, 2009 7:33 pm

ok, well wait... I'm thoroughly confused. Did you get them out, but now are wondering what they are SUPPOSED to be? or do you still need to find the proper bit to remove them? I'm assuming when they say hexagon, they mean that it is exactly that, a hexagon (5 sided), and that the hexagon bit is 10mm. They aren't referring to the overall diameter of the bolt head, just the bit you need to remove them.

I do think it's slightly overcomplicated :P
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Postby turboyoda » Sun Nov 08, 2009 4:21 pm

i have them out and they look like stock head bolts. i'm just trying to figure out what kind they are so i know whether the previous owners were using ebay or toyota parts. The only snag i'm hitting is the bgb seems to have a 10mm hex (6sided) bolt, while i've removed a 12mm double hex (12sided) bolt. i've read all over that they are supposed to be 10mm double hex from the factory. :shrug:

i thought this question would be one where someone who's done a head gasket replacement or two could chime in real quick with the specifics, but i'm getting to a point in my build where it doesn't matter what the previous owners were using. it'd still be nice to know though. :D
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Re: have 12mm head bolts, BGB says they're supposed to be 10mm??

Postby WarTowels » Wed Sep 08, 2010 2:14 pm

Dead thread, but if you'd like to know the answer, it lies in the picture.

You use a 10mm hex socket AND the SST.

The SST is a double hex/ triple square bit that fits inside of the 10mm socket.

If you look closely at the image you can see (from right to left): Standard 3/8" Extension, 10mm socket, SST(double hex bit).

So yes, you have the correct bolts, just confused by the BGB pictures/wording.

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