[Sinner 88]

Was working on tapping my pan to install the 3/8 NPT oil drain fitting. For what it's worth, the fitting is an aluminum one rather than brass.

I punched the hole using a plumb bob which seemed to work out great. I marked on the plumb bob how deep to tap in and once that was done I worked on threading the hole. The tap barely wanted to go in and it took me a good hour or so to tap the hole. I finally got it through and it created some threads.

Now for my issue - I cleaned it all up and went to install the 3/8 fitting. It seemed to thread in fine. Was a tad snug but not bad. I got about half way in and then I noticed it loosened up. I pulled the fitting out and the threads on the fitting were pulling off (threads are still there, just half of what they were). I ran the tap through again and it threads in fine and I can still visibly see threads but the fitting is junk now.

Any help would be appreciated before this somehow turns in a giant mess. I ordered a new fitting, along with a brass one to test the threads out with first. Any idea why it might be pulling the threads off the fitting?

 

[husky65]

When you say the fitting was snug, how snug? Being an npt fitting once it's tight it's tight, you can't keep going otherwise the stronger steel thread will strip the alloy.
I also used an alloy npt fitting. Put some rtv around it, tightended it up snug and that's it.

 

[Sinner 88]

Hard to say just how tight it was. Definitely was tighter than finger tight but it moved with a little bit of effort using a wrench.

 

[5.0thunder]

I used brass on mine the first time around without issue. Being that A) your fitting is aluminum, and B) the pan is thin steel that is only peeled back (plumb bob action), it's hard to achieve what feels like a nice tight fit. As said above, you just RTV the fitting and snug it up.

 

[Sinner 88]

Just curious but how far in should the fitting be threaded? For my AN fitting (the NPT side) i assumed it would need to go down to the almost the middle section where wrench attaches.

Also, how far should the fitting go in just using your fingers? I can probably get 3/4 to 1 turn by fingers when I tested out another fitting.

 

[husky65]

Depends on how deep you tapped it it. Being a tapered tap, the deeper you tap it the further the fitting will go in before it's tight. Once mine got finger tight, I probably gave it another 1/2 turn or so.

 

[Sinner 88]

Depends on how deep you tapped it it. Being a tapered tap, the deeper you tap it the further the fitting will go in before it's tight. Once mine got finger tight, I probably gave it another 1/2 turn or so.

I think I went about half way up the tap. After re-reading the directions it's definitely further up the tap than what Vortech recommending, but I didn't really see it causing an issue either (although I could for sure be wrong).

I appreciate the help guys!

 

[Sinner 88]

Got my new fitting and finally got the thing to thread in there. I took a brass one first to run it in and try to clean up the threads which seemed to work. After I ran the brass fitting through it, I had no issues getting the aluminum one in and snugged up.

Thanks guys for the help!