Accidental hole in cast iron

[graham-xrf]

I believe as long as you clean the hole very well, and follow the JB-Weld directions (for mixing and set-up time) it would provide a long-term, leak free plug.

How thick is the area with the extra hole?

Another idea:
Could you tap it and use a tapered pipe plug? (Along with thread sealer)
View attachment 359593




-brino

The "close it with a tapped seal" idea is great, but be careful of over-tightening if using anything tapered. Use some white PTFE plumbing thread sealer tape, and screw in gently, until enough that it will stay.

If the region around the hole can be regular enough, then a non-tapered sealing cap plug with a nitrile O-ring seal, or one of those Dowty types with the sealing ring incorporated into the underside of the cap screw head. These are very common pneumatic/hydraulic parts.

I say this because tightening a bolt into a hole in cast iron puts the iron into tension. Cast iron is strong in compression, but utterly feeble in tension.

By coincidence, I happen to be putting J-B Weld to the test (another thread). It does seem strong, and it does hang onto cast iron, and it can be reinforced with carbon fibre or class fibre strands if you want. I am using "MarineWeld" which is claimed to be "Chemical & Petroleum Resistant", and has strength 5020 PSI. This I take to be the tensile force/area at the point it fails. This stuff is the fastest, least stressful, and lowest cost fix. I would try this before any of the others.

The point made by @Nutfarmer is well made, but the thing is broken. You can try any or all of the suggestions, knowing in the end you need to find a replacement. It depends on how rare and precious is the housing. You can't just go fetch another part from the store for a '68 Caddy DeVille!

I am shortly to attempt welding on cast iron myself, though I seek to first have a "practice run" on some old disc brake castings. After consideration, the method will be to slowly heat up the whole part to about 300C, and use E-NiFe-C (55% nickel) rod, made for welding even dissimilar metals to cast iron. This mix apparently alleviates some of the stress shock from cooling with different temperature coefficients, and exploits nickel ability to "wet" adhere to cast iron.

In my case, the casting metal is 50% semi-steel. You can bet that a differential housing will also be of tough semi-steel. No way can it be plain grey cast iron as might be used for a railing ornament. It has to take a pounding from the suspension!

The method will be to heat the whole thing up to about 300C, then lay in welds a little at a time, with pauses to allow the local heat to even out, and not allowing it to cool. When enough weld is on, then lay it in a box of wood ash, or vermiculite (is that kitty litter?), and let cool slowly as possible. Then grind/file back to where I want it to be.

Direct experience from the farmer who lives out back of my place is that when he attempted a cast iron weld with nickel (pure), the weld went on, but cracked immediately it cooled. Undaunted, he just ground out the crack, and tried again. Second time around, attaching to the existing weld, he said it was totally different experience, altogether successful. I dare say casting distortion was not a concern to him!

 

[Aukai]

My dually rear end housing rusted through in a spot at the center section, JB weld did hold. I wire brushed, and ground down everything on the outside, I also used numerous cans of Brakleen to positively get all of the oil out of the area.

 

[MrCrankyface]

I was using an angle grinder with a cutoff disc to remove a extrusion on the differential housing which used to hold a bolt.
I figured the casting would be thick there to support the extrusion but as this thread proves, it wasn't.
I used a flashlight to check how it looks inside and it won't be possible to drill and thread since it opens up at an angle as the lines show.

The shape should provide a really good grip for the JB weld though, so it can't get pushed out.
I will try toget the area a bit more flat and see if I can screw a plate into the cast iron and then JB weld over that as well to make it a bit prettier..

 

[Mitch Alsup]

{Humor mode = on}
You could change the cam in the engine so it runs backwards, flip the sprag in the starter motor and wire + to - and vice versa, and flip the differential upside down.

Alternately, you could build a time machine and go back to yesterday and tell yourself not to be so ......
{Humor mode = off}

Personally, I would silver braze it--mainly because I already have the tools.

 

[Chewy]

Looks like the stuff that used to be brought to me. I spent years fixing farm and logging equipment, so I saw a lot of "mistakes". You cleaned up the outside so here is what I would do. 1. Try to find anything threaded that you can force turn into the hole. Pipe plug, bolt, electrical box connectors, just look around. If you can get it started and it is solid, coat the threads with JB weld and install. You only need 1/8" of threads inside, if that much. Minimum on the outside. In other words don't leave an inch sticking up. Use excess JB around outside and all over. It will hold forever. The rear axle is vented, so all you want is to seal the oil in and water out. Goes without saying that you need to make sure you have some clearance inside housing and that the JB area is clean, clean, clean.
2. Use a freeze plug or something similar to jam into hole. Do the same with JB weld.
3. Take off the back cover and put plate on inside and outside, install with machine screw like 10-32 through them. I put the head of the bolt on the outside and nut on inside, just me. Clean inside housing and plates. Use JB as gasket instead of RTV on both plates. JB the nut in place and JB all over on the outside.
4. Do the plate thing on outside. That involves drilling and tapping. Again use JB for sealing between housing and all over outside.
5. Welding is absolutely the last thing I would do. Brazing or silver solder first. Bear in mind that you will ruin the rear cover gasket when you do any of this. I would stay with cold repairs all the way. I have done nickel welding on cast iron blocks and things and it is the last choice always. If you do one of these, I would still JB over the outside.

If this is your first time, it is scary and your trying to figure out how much it will cost you. After a while it is an easy repair. Several years ago I rebuilt a 5L F150 Ford. Made 1/2 mile down the road and lost oil pressure. The Intake manifold freeze plug popped out. The correct plugs just didn't seem right to me. I switched to a disc type freeze plug. Put it as deep in the hole as I dared and then filled the hole and over it with JB. With 75K on the engine, it held 60 Lbs pressure at startup today.

3 years ago I had to JB an aluminum A/C suction line. That is done just slightly different with masking tape. It was still holding charge last fall.

My 2 cents. Good Luck!!

 

[tq60]

It can be soldered but that requires a bit of heat and skills.

I would make a cover that fits over the hole with good overlap.

Next a length of material that goes across the hole on the backside.

Drill and tap 2 holes, spaced such the screws rest in the ends of your hole.

Transfer punch holes to cover and drill for screws.

Use long thread bolt to hold inside part to cover and hook in the inside.

Align and place other bolt and make sure it clamps down tight.

Once satisfied it will properly cover clean all mating surfaces and make sure cover is sanded to allow grip.

Coat both surfaces with RTV or epoxy and assemble into hole.

Once in remove one screw at a time and add thread lock and tighten up.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Shootymacshootface]

Where abouts is the breather on that? There needs to be a vent somewhere.

 

[eugene13]

Most rear end housings I've dealt with are cast steel, clean it real good and weld it.

 

[LuJon]

Most rear end housings I've dealt with are cast steel, clean it real good and weld it.

I was thinking the same thing. Use the cut off scrap piece to test welding. If that isn't going to work. Then make a cover out of 3/16 plate and tap 4 holes in the housing to bolt it to. Flatten the area around the hole with a big bastard file so it has something to seal too.

Sent from my SM-N975U using Tapatalk

 

[Chewy]

If you decide to weld, solder or braze, the hole, you need to cover up the gears inside. The last thing you want is spatter and little drops of steel on the gears or loose inside

You could tack weld the plate on the outside and cover with JB. If it is cast steel, it will weld real good. If cast iron expect cracks and maybe the welds coming apart. Depends on skill and preheating. Personally for $5 of JB, and 10-15 minutes of work, I wouldn't take a chance.