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This is what happens when one has too many projects going on. I grabbed the wrong tap. The correct one (as pictured) is labeled 1/8-27 pipe USA 490. This is the tap I used to thread the pipe into the intake manifold. Sorry for the confusion
A pic of the tap would be great. Especially if you can show the markings on it.
Hey Stanz, I gave the wrong part number. I posted a picture in this thread of the correct tap but I want to make sure you get the correct part number as well.
1/8-27 pipe USA 490
This is the correct tap I used and sorry for the confusion.
I believe millball is correct; the gauge ports on these engines are tapped with BSPT threads. Autometer carries a conversion fitting from their NPT threads to BSPT. http://www.autometer.com/1-8-npt-to-...-pressure.html
So using a NPT tap not only doesn't match the thread form of the fitting http://en.wikipedia.org/wiki/British_Standard_Pipe , it doesn't have the correct pitch either. (an 1/8 BSPT thread is 28 pitch, not 27 like the NPT).
But since tapered threads seal by deforming the steel, you can probably get it tight enough to not leak even though it doesn't really fit. But I wouldn't remove that fitting any time soon; what you have now is some distorted compromise between the two thread forms/sizes.
Jared, you got lucky. I've confirmed that Toyota actually uses British Pipe through 1/8-28 (not US 1/8-27 NPT). You were off only one thread per inch and with your teflon tape and perhaps minor cross threading, you got away without a leak.
I don't have that kind of luck ever. I was able to find a BPT tap on Amazon. Went in perfectly.
I win some and lose some. Since I started the hole with a 9mm, it is possible that some cross threading occurred later on with the pipe tap. I did use tape (looks like you did too) but I think that's on par with any pipe being used. It's in there snug and holding fine....no leaks. Now whether or not I can take it out on a regular basis and expect it not to leak is another matter. But, if it lasts me another 350,000 miles or 30 years (whichever comes first), I'll be a happy camper. Good info on the tap type...thanks for posting that.
I have a 1st gen 4runner with the same threaded pipe coming out of the intake manifold. I'm putting the engine together now and don't know where that thermostat return hose goes to. Anyone got a pic, diagram, information? Thanks.
Awesome picture man, thanks. I did find an inlet on the bottom side of the intake that looked old and corroded. You said it goes under the EFI, happen to have a picture of where it connects? I wonder if it goes into this side tube I found. Thanks again.
I think you solved my mystery. I went out to the truck and looked under there and low and behold! an INLET! Here is a picture for anyone else interested. Is this where your's is plugged into? THANKS AGAIN bud.
Cool, I was just double checking to make sure it was the same fitting. Everything is hooked up now and I've been trying to start her. Keeps backfiring... damn 4 stroke. I gotta get the timing right and she'll turn over I'm sure. Don't think the neighbors liked my truck fire off "shots" at 10pm so I called it quits for tonight lol. Thanks again for the pic to get me on track.
Adding to an old thread. My 87 has the same 90 degree bypass union mentioned in an older post, but it looks like the previous owner of my truck threaded the hole and the original 90 degree union. An option if you want/need to keep the 90 degree setup.
Is that Lexus P/N thread-compatible with the original 90404-51060 P/N that OP found? That part has been discontinued by Toyota, but the Lexus one hasn't. I wonder if it would thread right in (my alternative it tapping and installing a different union but I'd prefer not to do that unless it's the only solution).
04-13-2015, 08:49 PM
Good info on the tap type...thanks for posting that.
