HOW TO: Remove coolant nipple from rear cast iron
 

I wanted to give some information back to the community being as I have got so much from this site. As usual when performing this kind of work wear safety glasses. And I take no resposiblity for your actions if you ruin your cast iron. I also apologize for the pictures, my phone really doesn't do very well here. Thank you!

So, before I began this project I searched to see if anyone else had done this mod. I found that there where lots of people that have done it, but found no real substance as to a walk-through on how to do it. The reason I wanted to tap and plug it was because I removed all coolant going to my throttle body and did not want to worry about have a coolant leak from the piece of hose with a bolt in it. I also did this same type of work on my upper intake. I removed all of the needless vacuume outlets and pluged them with 5/16" plugs. The type of work is the same, it is just less serious dealing with air in your intake than messing around with your coolant system.

Obviously my engine is apart and I am rebuilding, but having seen the pile of shavings that come off during the drilling and tapping process I would not perform this on a running/complete engine. FYI

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First is the tools needed. Not all that many really, not pictured here is the hacksaw and pneumatic grinder for removing the metal outlet tube from the cast iron. I am using a 1/4" NPT plug with an allen socket to finish this job clean and simple. I headed down to my local hardware store and picked up the tap 1/4" NPT and also a nice new drill bit to perform this, you only get one shot and drilling and tapping the hole correctly so leave nothing to chance here.

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So there is the bugger right there. The engine is going to look alot better without that nasty thing chilling under the intake for no reason. I am using a hacksaw to widdle this down a bit so I can get my grinder into the center of this metal nipple.

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Manage-able.

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Here is a shot of the type of grinder I used to get inside. That metal outlet has been in place for a long time, and it is really in there. So what you'll have to do is remove the metal on the inside of the tube down to the cast iron. I made straight lines on either side 180 degrees from each other running the entire length of the tube. Keep looking at what your doing though while you are grinding, you don't want to start taking away material from the cast iron. You are going to need all of the casting intact for when you tap and make your threads.

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Looks like this when done. After you remove the material from the tube, grab it will a pair of pliers twist and pull.

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Hold the drill as straight as you can all the way into the coolant area, you need to punch it all the way through to make room for the tap to be able to run deep enouph. Notice the pile of shavings? That would not fair well in your coolant system.

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Now for the business. USE LOTS OF CUTTING OIL. Cast iron is by nature a brittle and nasty metal. Help things along with lots of cutting oil, and by going slow. Also stop and remove your tap to clean all the tailings off the bit oftain, I believe I cleaned mine about 4 times to make this cut.

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Tailings

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Woooop there it is. She is a thing of beauty!

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I am a pipe fitter by trade, so I would strongly advise you to use pipe dope of some kind. This not only provides a great anti-siezing benefit, but it helps the plug to thread in smoothly without damaging the cast iron. Then apply thread tape, it goes on clock-wise so you don't un-thread the tape while you tighten the plug :)

http://i889.photobucket.com/albums/a...2-11152829.jpg

All done, and it looks great!

Nice job there. I've done similar on rear plates that lack a tapped oil pressure hole (R5 most commonly found in '79-'80 RX-7s but also J-spec Cosmo engines from that era).

Now I have a question. Why do you use pipe dope and thread tape? Isn't it usually one or the other? Thanks.

From how I deal with pipefitting is that the dope performs more of a job of aiding in removal many many years down the road, or in time depending on application.

Steam pipes, anti-freeze systems, wet and dry pipes all fair very well with dope on them to help the fitting from bonding to the pipe. Often times we walk into a building that we are remodeling, or performing a service call on a system that has 50 years on it. Most older systems where assembled with tape only and it makes it a very tough job. Broken threads in fittings is the biggest problem due to lack of an anti-seize compound.

This application would be no different beings as it is an area that will be exposed to anti-freeze and more than likely air pockets forming there. Who knows I may want to remove that fitting someday, its good to plan on being able to remove it if you have to.

Cheers

I was contemplating drilling and tapping mine also, but ended up using an expansion plug to plug mine. If I were rebuilding my engine I would've drilled and tapped, but my engine is staying together for now(hopefully lol)

I wish the previous owner of my FD did this mod. Subscribing for my rebuild.

it's not necessary to remove the bottom shoulder of the cast iron past the pipe fitting by the way, i leave it in so that the pipe plug has a shoulder to seat against to tighten firmly down against otherwise be sure not to tap all the way through into the coolant passage or the plug will only be lightly snug and can work loose eventually if you do not use decent threadlocker.

It is also not necessary to hack saw off the nipple, then dremel it out. The nipple is just pressed in, simply take a small hammer and tap it sideways until it is bent at a slight angle. Then just give it a couple taps to get it spinning, comes right out intact, without all the extra work.

If the nipple is completely rusted through this does not work, and you just end up drilling it out.

NPT Type threads are tapered so there is no chance in the plug going into the coolant passage. By the time the plug is flush with the cast iron it is REALLY tight, if you don't tap it far enouph the plug will actually sit above the cast iron and will not have fully seated.

I actually had a practice cast iron to perform this on to see if it would work good enouph to do on my actual engine piece. I tried to just bang and twist and pull the nipple out and it ended up destroying it :). I just skipped the fustration step all together and just hacked it out on this write up. Its worth a try to pull it out without the grinding, but in the end the grinding only takes 3-4 minutes.

Thanks

i missed that it was an NPT pipe plug, for some reason they're usually a bit more difficult to find in most hardware stores so i just tap it out with a standard thread and use a standard size pipe end plug. it's less work that way anyways and works the same.

I just welded mine shut. While the engine was installed in the car. Just reached in aanndd ZAP! Took like 3 seconds ahaha.

here is an old post of mine from elsewhere with the relevant drill and tap sizes and options

would you care to enlighten us on your "transseals water seals"?

Good writeup.

Here's a video example of doing the same procedure. In the first 3 minutes of the video:

http://www.youtube.com/watch?v=v-0Yl_Jlx1w

The key is being very, very slow and reversing the tap often. A friend of mine cracked a rear iron tapping too quickly last summer.

Aaron, I tap the front side of the waterpump for M10 x 1.5 (coarse) because it's going into aluminum. :)

Thanks Aaron! Great video BTW I ended up getting sucked into watching most of it. Always interesting to see how others do rotary work. Great addition, thanks!

I`ve been doing this way for years,

As a word of caution to all choosing NPT plugs/fittings, do not over tighten the tapered plugs and fittings. Particularly in the thin irons. I've seen cracks form from over tightened tapered pipe plugs in 13b irons and everything else from piston engine heads, cast aluminum oil pans and modern FWD transmission housings.

Just as the tapered tap can crack an iron, so can an over tightened tapered plug.

I used a finer thread because the bolt would be shorter and I wanted more grip. Though I should have just welded the hole that seals against the gasket instead of tapping and plugging it. Not sure what I was thinking there...Too late now because it's painted and I don't want to have to blast and paint it again.

Part 11 will be out soon.

The chance of this is lessened by the use of aluminum fittings. Also it is worth checking the NPT tightening charts because I think 1/4 NPT fittings only go to about 14 FT-LBs. Most people just crank them down.

awesome write-up

Aaron rather than spending 2 hours taping up housings, it is possible to dummy up the motor with about 5 bolts finger tight and then just tape over the intake and exhaust ports. Its also kinder to the environment not using all that tape.

I thought of that, but I would still need to mask before painting and in that case would end up touching all the freshly blasted metal. 20 feet of tape won't kill the planet, I suspect. :)

I just did this with the engine in the car, and it seems to have went well... I'll update the thread if I kill my water pump or turbo somehow (not sure how the coolant circulates in the turbo).

https://lh3.googleusercontent.com/-u...SET%25255D.jpg

a few things of note:
- when tapping NPT you shouldn't tap until the whole tap goes in, because the tap is tappered, you'll just start widening the threads. I read on the internet that a decent way to do it is tap till about 6-7 threads are showing on your tap.

- I used a small magnet to get all the filings out of the engine. It seems to have worked really well, cast iron is pretty magnetic :) I stuck the magnet down the hole a few times over the course of drilling and tapping and would pull out about an inch of magnatized shavings each time. I was surprised the magnet worked that well.

- I also just used a hammer to get the nipple out, it was pretty easy, it came out much easier than I thought it would.

^I am planning on doing something about my rear nipple come the better weather...

I was also thinking magnet, or a strong vacuum? I know it sounds silly. In my case the engine is fine, but I will have everything apart when I do this. I actually USE this nipple as I have a thermowax because I am weird. :) It is pretty worn out it needs replacement. I figure if everything is apart when I'm doing this, I can flush out the system thoroughly after with no worries of metal shavings?

With the cast iron being very heavy I would imagine it will just find a home at the bottom of the engine block some were. Looking good!

I have had my engine running for over a year now and could not be happier about not having a tube with a bolt clamped in it back there. There are enough things to go wrong on these cars, no need to worry about something like that!