Mark-87-951

When I did it the tapping tool I used wobbled and apparently screwed up the hole enough to prevent the threads sealing tight enough. I had a very minor leak. I'm getting another head and willing to try again. Is it possible that having a cheap tool would be what screwed me up? it was part of a tap and die set I got at Harbor Freight.

dand86951

Is it a 1/8" NPT thread? If so then you could use the same head and go p to a 1/4" NPT and then put in a 1/4 to 1/8 brass adapter. If the tap was not perfectly round then yes it could be the cause. Or you could have just angled it incorrectly or threaded it too deep.

Mark-87-951

How does one know when to stop threading in this case? I'm getting a different head. I had a new timing belt fail, split lengthwise and this head has been resurfaced a few times already and Im getting a good deal from Lart one a used one ready to install.

dand86951

In this cse since it is through the wall of the head which is only about 3/8" thick, IIRC, then you don't want to turn the tap all the way through. You go in say less than mid way on the tap and then check the fit with the plug or connector. Best to do when head is off the car obviously.

zerMATT951

First of all, make sure you aren't drilling the hole too large. When you are tapping the hole, stop once you think the end of the tap is 1/8-1/4" inside the head. That way the elbow should be plenty tight when you thread it in. In fact, I'm pretty sure my tap bottomed out (slight scrape) inside the head when I was tapping, and the elbow was plenty tight when I threaded it in.

If you weren't set on replacing the head already, I would even consider making several extra rounds with Teflon tape to tighten it up.

Mark-87-951

I know I drilled the hole per the size Lindsey stated. Maybe I screwed it up at that point? I'll make sure to get a decent tap this time.

zerMATT951

21/64 on the LR site agrees with the tap size card in my Snap-On set, and that's what I used too. Sounds like you may want to try another tap or just don't go in as far.

Did you use plenty of Teflon tape and make sure the freshly-tapped threads weren't cutting out the Teflon as you screwed it in? My hole had sharp edges and it wanted to take the Teflon off the elbow as I screwed it in the first time, so I pulled it out and cleaned out / smoothed off the top of the threads with a tapered stone bit in a die grinder before trying again. The Teflon stayed intact that time.

Mark-87-951

Didnt add tape or check the edges of the thread. I'll do so this next time. My set isnt snap-on just a cheap one I found at Harbor Freight.

reno808

zerMATT951

Always so helpful...

kev951

use a tap socket with the tap. much more control

Tom M'Guinn

It's an NPT thread, so it gets tighter the more you turn in the fitting. I went with the teflon that Lindsey pre-installed on the fitting, and tightened the snot out of it (to the point where the fitting was starting to cut a little probably). If your threads are clean, you can probably just re-apply a good teflon coating and tighten it more to get a good seal. On the other hand, Harbor Freight tools are cheap, in every sense of the word....

Mark-87-951

I would think using a wrench would make it more difficult to avoid wobbling the tap unless I'm misunderstanding how a tap socket works.

Mark-87-951

Oh I did tighten the crap out of it. The leak was very small. The fluid would actually congeal rather than run down the engine the leak was so small. I think I screwed up at drilling the hole or wobbling the tap or both.

zerMATT951

I like using t-handles with taps the best, that gives you the most control and prevents wobble. Just make sure the tool is perpendicular to the hole when you start and take your time. Aluminum cuts quickly, so it's easy to get off-course. Use a tiny amount of cutting oil or some other lubricant too, that makes things go much smoother. Only go 1/4 turn at a time into "new meat" each time, then turn backwards 1/2 turn to clean out the metal you just cut.

I would think that even an inexpensive tap wouldn't have a problem with aluminum unless the shape/dimensions of the tool itself are all wrong. Cutting aluminum with a cutting tool should be about the easiest task that tool will ever do. Now if you get sideways and put the tool in a bind, it will snap pretty quickly or break off some teeth... that is the area where a more expensive tool will hold up a little better, but tool steel is very brittle no matter what brand it is.