Tapping out cast iron block

bc

Well-known Member
Well guys, was working on my Ford 1500 this afternoon doing some odds and ends so I can move it out of the barn to work on my 2606 next week. This 2 cylinder Shibaura diesel has a radiator drain that comes out the block about half way up on the left side above the starter. I ended up breaking it off flush with the block. The radiator drain appears to be aluminum as it is soft metal. Since it is aluminum I can't just put a welder on it. The easy out I had was too small. As soon as I get the right size easy out, I assume it will come out, I hope anyway, but I may need an extension on an easy out.

This hole in the block I believe is some type of 3/8" british G tapered thread or else metric. The tapered G thread used by the Japanese builders has a different taper and a slightly different thread count than a 3/8" NPT. Assuming I can find some type of extension to get on a 3/8" pipe tap so I'll have some leverage, how hard is it to tap a cast iron block to NPT? Thanks.
 
Cast taps easy .
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Cast iron is easy to cut threads in. It is easier that some aluminum s even. The chips are usually small chips instead of being stringy.
 
Easy outs are the last choice for me in
almost every situation other than
fittings that have been sheared off,not
twisted off during a removal attempt. it
was me I would forget the easy out.
Reason being if you break it off, which
happens often then you have a real
problem on your hands. If you try it be
very careful how hard you pull on it! You
are correct that the thread is not our
standard NPT but BSPP British Standard
Pipe Parallel or BSPT Tapered aka G
thread. The easy way to know which you
are dealing with is a BSPP fitting in
that application would have a machines
flat surface and a sealing washer used.
If there was no sealing washer you have a
BSPT fitting. Although NPT and BSPT
fittings will screw together easily part
way they will not seal as the TPI
differs. If I was in your situation I
would use the proper size tap drill to
remove the bulk of the fitting followed
by a BSP tap to remove the rest. With
just a bit of wiggle, good lube and good
judgement the tap will follow the softer
aluminum and not damage the block
threads. If you must try an easy out heat
the aluminum fitting a few time s with a
torch followed by cooling with a squirt
of water.
 
As far as an extension- I have a couple sets of 8 point sockets. And I got every little 4 and 12 point socket available so that I can extend most any tap. Should work likewise on an easy out.
 
Throw away every ezy-out you own. If it breaks you are facing a major problem. they will work 10% of the time at best and never on a thin piece like
pipe. Carfully drill out the broken piece and then re-tap to 3/8NPT. A little sealer on the new fitting and good to go.
 

Thanks guys. Have a plan now. I'm putting a set of gauges on it and Bob previously advised me about the british thread. I still wanted to keep the idiot lights so I was looking for a tee for the oil sender to keep it and add an oil line. Thought it was a metric thread and after a month on order it finally showed up by slow boat. Turns out it isn't a metric thread after taking out the sender and the fittings were reversed on the tee. So I guess I will tap that out as well for NPT and clean up the sender thread with a die. The sender thread is a little boogered up and looks like an original blue but I wonder if it is really NPT.

For the water I can't tee off the block where the sender is so that left me with 2 choices. That drain valve in the block or one that goes into the radiator hose so I ordered a G thread adapter.

Because of that drain handle, head, and starter, I was working at an angle with a crescent wrench and it broke off flush with the block. There is a hole there so I can't leave it. The largest left hand bit I had was a 1/4" and found that the aluminum drills real easy but it didn't extract. The largest easy out I could find was also a 1/4". Looks like it is corroded in so I will drill it out. When I looked at the block I got to thinking about an old cast iron stove and thought it might be too hard to tap or else so brittle that breaks up.

Sorry but I can't drive a tractor without knowing what the temp, oil pressure, and voltage are because who knows if the senders for the idiot lights really work or what setting they have. Someone said that the temp probe needs flowing water to work so if that is how it turns out then I will get one for the upper hose and put a NPT drain back in the block.

Thanks. Long post but I know that someone will ask something. Oreillys carries the pipe taps.
 

If you have access to an oxy-accylene torch with a relatively small heating tip this would be easy.

Heat what's left of the fitting darned HOT, allow it to cool to ambient, repeat, and repeat again.

At that point, after it's cooled off the last time it will be broken loose and will come out EASILY.

The idea is to quickly heat up the broken part and NOT heat the surrounding cast iron any more than necessary.
 
As for the broken plug in the block, is the hole in the plug small enough to drill with an R drill and tap it 1/8" NPT?

The temp sender needs to go somewhere in the head or thermostat area. Putting it down in the block will give a false low reading.
 
I've been trying to remember what I did- I think- working on oil pressure sender, I ordered 1/8" brass British close nipple and tee from McMaster Carr. Their shipping is almost immediate. Then I tapped one end of the tee to NPT 1/8" for the added, manual gauge oil pressure line adaptor.
 
(quoted from post at 09:42:37 02/20/21) As for the broken plug in the block, is the hole in the plug small enough to drill with an R drill and tap it 1/8" NPT?

The temp sender needs to go somewhere in the head or thermostat area. Putting it down in the block will give a false low reading.

Just realized I'm wrong on my sizes cause at Oreillys last night I was screwing the sender into a bolt gauge which was 3/8" size then the Oreillys guy said something about a 3/8" pipe tap. Technically I think the oil sender is an 1/8" so I would need a 1/8" pipe tap and the block drain valve was 1/4" British so I need a 1/4" tap.

I have an adapter for the block drain but I just as well tap it out. I ran a 1/4" left hand drill into the old block drain and it just cut a little leaving quite a bit around it. Think I could carefully drill out that aluminum. The block drain is about half way down just under the head but above the cam which is above the crank. It is probably only about 3 inches below the present sender. Guess as long as I know it could be a little low, I can deal with that. Either way, when the heat starts to rise above normal, I'll know it.

Bob, I haven't ever used McMaster Carr. First go to has always been Amazing and fleabag.

That darn oil gauge came with this 1/8" plastic line with compression fittings. The male end sticking out of the gauge takes a compression nut thread. I'd like to go bigger so I can use copper tubing. Oreillys and Ace didn't have it. Now I see if I make a road trip I can get it at Napa.

Good thing my labor is cheap as I've spend more time on this little project than it should take for an American tractor.
 
how about a small file that will fit inside the broken off
sender . and then file a groove almost to the threads, and use
small chisel to split it at the thin part ,
 

If the hole in the broken off part is in the CENTER, you could continue to drill it out until you are using a drill bit equal to the smallest root diameter of the pipe thread.
Then with a saber saw blade for metal in vise grips, cut a slot or two in the remaining aluminium.
Then pick, peel and punch out the remains.

Using an ezee out for that plug in what might be thin cast iron, could cause the cast iron to crack as it screws into the broken part.
 

Got the broken radiator drain out yesterday. Thought I'd try heat before drilling out like Old said. Heated it with the torch, sprayed some juice, and didn't budge with the easy out. Heated it again, stuck some wax against it, and it obviously shrunk loose. Came out easily with an easy out. Not sure if it was made of aluminum or some kind of pot metal.

Tapped out the block for the oil sender. That was easy to do going from the british G thread 1/8" to 1/8" npt. Run a die over the sender. Of course now a bolt head on the clutch housing is sticking out so I need a pipe extension.

Thanks guys.
 

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