kibbleking

Hello, I'm replacing the head gaskets on my 93 pickup has the 3VZE V6. I was reading maybe in this forum that its a good Idea to chase the threads in the block before putting it together. Does anyone here know what size thread chaser I need ?? 10mm ? 9mm bigger ? smaller ?
And would using Loc-tite be a good or bad thing ?
All i can find about that is just oil the threads and under the heads of the bolts? Am I on the right track here ?

Thanks

Clancy..

millball

Its not just a good idea to chase the threads, its essential.

Locktite is useless on the head bolts.

Take one of your headbolts to the auto, or hardware store and get a tap of the same size and thread pitch as the bolt.

scope103

Taking it to a hardware store will work.

But you'd be surprised how often you would use a simple thread pitch gauge:

And a digital caliper is a god send!
http://www.harborfreight.com/6-inch-...per-47257.html

Gently avoid plastic "screw checkers." They do work, and they are usually not very expensive, but it is very easy to damage one when "screwing in" the fitting to test the thread size. (Okay, I own several of them. Fine for sorting loose parts.)

Don't use any kind of thread locker. It's worse than useless; it could make it very difficult to remove a head bolt in the future (not that you're planning to do that, but still ...)

kibbleking

Thank you. making trip to hardware store..

rustypigeon

I prefer to use a thread restorer rather than a tap. A tap often removes too much metal, as opposed to cleaning debris and straightening threads like the restorer does.

I have the Lang Tools 2584 kit that sells for $36 on Amazon. It covers probably all the thread sizes you will encounter on a Toyota, and most other cars. Living in the rust belt, I use mine often.

scope103

Since no one answered your question (especially me!):

3VZE Head Bolt Size: M12-1.25

I'm not really convinced that a 'restorer' is designed differently than a tap (is it not hardened? Cut with negative rake?), but rustypigeon is correct about taps: they are designed to cut metal, and you don't want to do that. Be very gentle, don't cross-thread it, and if it starts to get moderately snug, stop! Clean the debris out of the hole with compressed (shop) air, and wear safety glasses when you do that.

rustypigeon

I have in the past used taps and dies to clean threads and ended up with a loose fitting bolt. And that was after being careful.

Out of curiosity, I measured my 12x1.25 tap and my 12x1.25 thread chaser and the tap was .010" wider.

Here is and excerpt from and article on taps and thread chasers...
http://www.autoserviceprofessional.c...threads?Page=2
When you need to “restore” or clean-up “boogered” threads in a critical engine component, such as the cylinder head threaded holes in an engine block, avoid using a normal cutting tap. Instead, use a “forming” or “chaser” tap that is specifically designed to chase and re-form the existing threads instead of cutting thread material away.


The thread chasers/repairers that I have look just like the ones pictured in the linked article.

SR5ALLDAY

bull˟˟˟˟ that is not the correct size to chase the threads.

millball

SR5ALLDAY is correct.

3vz headbolt threads are 11x1.25 NOT 12x1.25