Looking for method to thread water pump heater hose

On my Chevy 250, I need to get some threads into the lower heater hose port... the one located at about 10 o'clock on the water pump, just above the lower radiator house port.

The plan, at present, is to grind inside the port to get it nice and clean/grindy. Then take an appropriately sized face washer (a face washer is a brass fitting that has NPT fittings on the inside and outside, like a bushing, but no hex shoulder... it's just threads... and because it's NPT, it's "sided"), and after masking off the inner threads really well, pookie-ing the hell out of it with America's favorite... JB Weld, and plopping it in the hole. Once dried, I'd have NPT threads to work with.
I've used JB weld before for "fixes" as cheesy as this, but I thought I'd run it past some experts (at cheesiness? ) before going this route.
Does anyone have a better solution they'd like to offer up? Does anyone have any objections to this solution? I'm open to solutions that go over the end of the port, but the finished product has to be very "neat" and as unobtrusive as practicable. In other words, it can't be a piece of heater hose with a hose clamp holding it on, and a fitting jammed in the other end with another hose clamp keeping it tight. That is neither neat, nor unobtrusive.

 

I think you would be better off using the appropriate size tap. then use the high heat white thread sealant. more pieces in the equation equals more places to leak. use plenty of cutting fluid

 

Two thoughts. In my experience, JB weld is fine as long as it doesn't get too hot. If it does, it breaks down and falls apart. Any chance of tapping the inside of the port, and using an adapter to get to the thread-size you need? Take it to a good plumber-supply store, and see what they have.

 

Drill, tap and plug as TudorKeith suggested. It doesn't take reinventing the wheel to do a clean job of it. If you want to shorten it a bit, check to see how much metal you have behind the extension that you can drill and tap for a pipe plug if you cut it off.

From what you wrote you are going overboard trying to make things complicated when the solution is so easy. I'd probably want to leave a quarter or three eights of an inch of that stub sticking out to have enough to tap into. At least until I could tell how much I had to work with in thickness right there.

 

The problem with tapping the inside of the port is that it's an oddball oval shape as a result of the casting. If I drill it out to round, I'm not sure how much wall I'm going to have left. And I would need some wall strength there since NPT is a "wedging" thread. I'll take a micrometer out to the garage in the morning and see what I might be dealing with for thread size after all the dust settles. I have a 3/8" NPT and 5/16" NPT threaded scrap part that I tried to test fit today, but the casting also has a lip on the opening... so combine that with it being oval shape, and there's not much that's going to fit until I drill and grind quite a bit more.

Has anyone ever seen a rubber plug that could be tightened in place (and, of course, give me threads when it's done)? Picture how the arbor works on your Dremel's 1/2" sanding drums. You slip the rubber into the drum, and then by tightening the threaded part, it expands the rubber. Maybe something along those lines??? Problem is, I'm dealing with some pretty limited space, even after I get it more rounded in there.

 

We must have met.

 

You need a 1/4-3/8 close nipple or a reducing hex nipple

 

He is trying to cut the nipple that is on there off and plug it for a cleaner look because he isn't planning on running a heater in what ever he is using it in. At least that is what I can gather. The easy fix would be to put one of those little rubber caps on it with a hose clamp but that would still stick out like a smashed finger.

 

Why is that? That seems to just be a decision on what kind of threads I need... and that's not them. I need 3/8" or 5/16" female NPT _inside_ the port on the water pump.

 

find a rebuilt pump that used an old GM core, so it's a nice round hole....

 

OK, tap the hole xx NPT and plug it with a socket head NPT (pipe) plug.
1/8" NPT Drill size "Q" .322
1/4" NPT Drill size 7/16"
3/8" NPT Drill size 9/16"

 

why not try to just have a really big threaded a/n fitting welded on the end with a tig than have a hose made to screw into that ..just my 2c

 

XXL, should be pretty easy to fab up a plug that works like your dremel sanding drum. A piece of dense rubber pretty close to the id of your hole,(tight silde fit would be ideal) a couple of brass washers just a little smaller, the bottom one being thick enough to hold a thread, find a suitable size brass screw and tap the hole in the bottom washer to that thread, have a running fit in the hole on the top washer. Drill hole through plug that you can just force the screw through. Sandwich the rubber plug between the 2 washers with the screw through them , insert flush with the end of the hole and tighten the screw, should expand and seal good, just leaving the screw head and washer exposed at the end of the outlet. Works just like a boat plug.

 

Find a fitting that is close in size to the irregular ID of the hole and braze it into place.

 

Maybe if you could be a little more clear on exactly what you're trying to do ? Do you want to plug the hole or have external threads sticking out of the port when all this is done ?

 

Best method:

1. Bore the hole so it is round, not worrying about the thin walls.
2. Get a piece of softer metal tube, aluminum or brass, that is slightly larger than the new hole and able to take a tap of the threads you want with room to spare.
3. Bevel both ends of the tube.
4. Heat the casting.
5. Freeze the tube.
6. Drive the tube into the hole.
7. Run some epoxy around the top bevel.
8. Run a tap down the hole.

I've never done it myself and never seen it on a car, but I've seen the process used more than once on machinery.

My method:

1. Soak a piece of wooden dowel about the ID you need in water.
2. Stuff the hole with epoxy putty.
3. Put the wet dowel in the middle.
4. Allow the putty to start to harden, but not all the way, then remove the wet dowel.
5. Wait 48 hrs.
6. Tap hole.

The putty won't stick to the wet wood and unlike the practice of putting WD-40 or whatever on a bolt that I have seen, there is no risk of chemical contamination in the putty. This method I have done.

 

Your idea will work fine. There is no need to overengineer or overcomplicate this. The ground up surface in side and the external threads on the face washer will give your JB plenty of tooth.

No reason to worry about heat as that part only sees coolant temperature and you are well within limits. If your water pump ever see more than say 250 degrees then your car is on fire or you have some much more serious problems elsewhere.

The only thing I would suggest is to use Marine Tex instead of JB Weld. Marine Tex is JB Weld all growed up. It is used in the marine trade to replace broken off engine componentry. It has the right coefficient of expansion and (although not needed here) can be machined and tapped when cured. Available in black or white. Just mix it 5 to 1 and go.

 

If all your trying to do is plug the hole.Just drill it round and knock a freeze plug in it. It wouldnt matter if it was a little thin cause your not trying to thread it

 

Thanks all. I need threads for a 3/8" inverted flare line that will feed the water jacket under the intake manifold. I have already plumbed the return to the top heater port, which used a threaded hose barb... So that was easy after unthreading that bung.

On this one, I spent 30 minutes drilling to a reasonable depth... And I am now trying to run my expensive 3/8" NPT tap... to no avail. I am now firmly you cannot CREATE threads in cast iron. This weekend I will involve growd-up JB Weld!

 

I don't know what is going on with your tapping issues. Cast iron has always threaded really easy for me. Are you sure the drill hole is deep enough to clear the tap's taper? Maybe it is bottoming out before it starts cutting?

 

I'd like to see a pic of the engine you're working on.......

 

Where in Calif are you. If your close to san Mateo maybe you could bring it over here and we can put it on my Bridgeport and try to think of something.

 

I am drilled >1/2" deep. I can't get the tap to start. It is a brand new Irwin case hardened tap. It simply has no interest in making even the first dig.

 

you are trying to tap with a 3/8-16 NPT tap correct? is the hole drilled at 9/16? you said you had to drill a long time, did the hole become oblong? if you are having that much trouble starting the tap something is wrong, the tap is tapered, it should start pretty easy and get harder to tap the deeper it goes.

 

I'm _real_ close... I'm in HMB. But the pump is on the motor and I was "planning" for this to be a simple project :-(. I do have about umpteen other projects where a mill sure would come in handy ;-)

I'll post pics when I can. I'm playing hunt and peck on an iPod right now... And not paying attention in my meeting. Oops.

 

for one thing take the pump off of the motor and find a way to clamp it where you can see what you are doing. Chances are the tap might be starting in crooked and it needs to be eye level so you can see it's going in true.

 

Drill was jogged up to keep it square. Bit is (also brand new Irwin HSS) 37/64" as called for by the tap. Hole I cut is round per micrometer. This is, IMO, a material issue.

 

Jogged = jigged. Thank you, Apple, for the "correction."

 

some charts call for 9/16 some for 37/64 i always drill 9/16, something is wrong if you are having that much trouble starting it, I work with cast steel and cast iron at work all the time, and I've never had that much of a problem with it. I know this is a stupid question as you seem like you know what you are doing ,but that is an NPT tap isn't it?

 

Use a tapered pipe tap reamer before tapping and it will go easy.