What is the thread/pitch??

[chadly]

Pulling apart the intake I messed up the threads a little bit on this hole. Can you tell me what tap I need to buy to chase out the threads or is there a better option. Threads are not terrible but something must be done. What sucks is I was told to leave it in but I tried to get it out anyway.

 

[forcefed3.8's]

1/2" npt

 

[87GNSteve]

........ What sucks is I was told to leave it in but I tried to get it out anyway.

Well for future generations; NEVER try to take that fitting out!
Good Luck.
I have seen worse. Ones that needed to be welded, redrilled, and tapped.

 

[chadly]

Thanks. If I run a tap in and clean up the threads is there something I can apply to the threads on the bolt to be sure it does not leak?

 

[chadly]

Well for future generations; NEVER try to take that fitting out!
Good Luck.
I have seen worse. Ones that needed to be welded, redrilled, and tapped.

I thought I would give it a little pressure on the wrench and see what happens. Well it broke free and turned about a full turn then got tight. It would not got either way now. So I figured I better take it out and see what I did. Stupid me. Why is it that I just cant listen.

 

[87GNSteve]

Thanks. If I run a tap in and clean up the threads is there something I can apply to the threads on the bolt to be sure it does not leak?

Use the Permatex thread sealer with teflon that we use for head studs.

 

[novaderrik]

run the proper 1/2NPT tap thru it, then install the fitting dry. pipe fittings are tapered and don't require any sealant. it won't hurt to use asealer, but it won't help, either, unless the threads are really buggered up.

 

[Dabigguy]

The Permatex with teflon will help seal as well as lubricate the threads for tighter assembly with less stress on the already damaged threads.

 

[Jerryl]

Worst case scenario :wink::

If the thread is ½ NPT, and completely stripped, get PN 661621 at Autozone.
It is a ¾ - ½ NPT bushing which allows you to tap the current hole to ¾-NPT, insert the bushing and you are good to go.

As stated, NPT threads “should” not need sealant, and Teflon is really not a sealer but a lubricant, which allows you to tighten the nipple even more.

 

[turbofabricator]

I the world of aviation, you MUST use sealant on pipe threads. I ALWAYS use sealant or teflon tape. Do NOT over tighten that fitting or it will crack the manifold. If the treads ar buggerd up, do as Jerryl suggests, or just buy a new fitting with the 3/4" thread size (NPT) Be SURE you tap and install a reducer fitting INSIDE any new fitting or you will pop your heater core.

 

[LOT]

Maybe a way to save it

You will need a 1/2 NPT tap. A correct depth pipe thread (male and female) will leave 3-4 threads exposed. Tap the hole and go a couple threads deeper. In other words almost bury the tap--leaving 1 thread showing. Now if the fitting goes in smoothly and starts to get tight with 2-3 threads exposed. Once tighten it should be ok. Not a lot of pressure there. Use liquid of ribbon teflon pipe dope on threads. This lubes the threads making for deeper engagement. Best of luck.

 

[chadly]

I the world of aviation, you MUST use sealant on pipe threads. I ALWAYS use sealant or teflon tape. Do NOT over tighten that fitting or it will crack the manifold. If the treads ar buggerd up, do as Jerryl suggests, or just buy a new fitting with the 3/4" thread size (NPT) Be SURE you tap and install a reducer fitting INSIDE any new fitting or you will pop your heater core.[/QUOTE]

Thanks for all the help. I think I will do as Jerryl suggested and just be done with it.
Ken you lost me on your last sentance. Can you explain?
Thanks again.

 

[chadly]

You will need a 1/2 NPT tap. A correct depth pipe thread (male and female) will leave 3-4 threads exposed. Tap the hole and go a couple threads deeper. In other words almost bury the tap--leaving 1 thread showing. Now if the fitting goes in smoothly and starts to get tight with 2-3 threads exposed. Once tighten it should be ok. Not a lot of pressure there. Use liquid of ribbon teflon pipe dope on threads. This lubes the threads making for deeper engagement. Best of luck.

That's a great idea! However do I stand a chance of cracking the intake by doing this?

 

[turbofabricator]

The factory heater tube fitting has a restrictor INSIDE the tube. Look at the small hole inside. It is not the standard ID of the fitting. I just run a 1/4NPT tap in there and screw in a brass pipe plug, then drill to size. (sorry, but I don't recall the actual size, but I think it's 3/16", but measure the factory one to be sure......use a drill bit to measure.) If you just screw in a new pipe fitting (using thread sealer) the volume of water that goes through it will pop the heater core. Ask ME how I know that.:redface:

The amount of torque required to break the casting is pretty heavy. If you use a std 1/2 ratchet to tighten it, you probably can't break the manifold.

 

[chadly]

The factory heater tube fitting has a restrictor INSIDE the tube. Look at the small hole inside. It is not the standard ID of the fitting. I just run a 1/4NPT tap in there and screw in a brass pipe plug, then drill to size. (sorry, but I don't recall the actual size, but I think it's 3/16", but measure the factory one to be sure......use a drill bit to measure.) If you just screw in a new pipe fitting (using thread sealer) the volume of water that goes through it will pop the heater core. Ask ME how I know that.:redface:

The amount of torque required to break the casting is pretty heavy. If you use a std 1/2 ratchet to tighten it, you probably can't break the manifold.

Got it. Thanks.