OT: Cast Iron Repair - Hole in Coolant Manifold Reservoir

[CatMan]

What you see here is the underside of the coolant reservoir off of a '48 Farmall Cub. Rust has taken it's toll and left a hole that's about 3/4" across at any widest point. I need to get this hole repaired. But what type of repair?

Piece is cast iron. Weighs about 40-45 lbs. Radiator cap says it will blow at 7 lbs, so not a lot of pressure in the system. Access on the reverse side is limited by a sleeve in the casting for the (hand) cranking arm. Material around the hole feels solid, but obviously getting thin next to the hole.

Initial thought was to drill the hole out round ( to say 3/4" dia ), and then slip in a 1/2" NPT black iron or brass plug or bushing. Then braze the plug/bushing to the housing. But I've also entertained ideas of a plate to cover the hole. I've considered brazing vs. welding. Heard talk of making a "cover" using fender washers and thick rubber washers squeezed together with a bolt through the hole. Thought about just drilling out and putting in a freeze plug, but probably not enough wall thickness. Some have mentioned that maybe even just a plate with silicone or RTV sealant would work.

Piece is kind of rounded on this bottom side. There's a little ridge going to the petcock drain. And access from the bottom is somewhat limited, but manageable.

What's your ideas? Please don't say buy another. This is the original piece to the closest thing my family has to an heirloom. And I don't care too much about cosmetics either.

 

[magneticanomaly]

I would first "survey" the inside, through the hole with a bent wire if access to other side is bad, to see if it is paper thin or badly pitted over a large area.

If okay, I would clean to bright metal around the hole with sanding or grinding disc, and then braze, being careful to preheat the whole piece over charcoal so as to minimize chance of cracking it.

 

[CatMan]

I've plinked around the hole with a hammer. All surfaces around the hole sound solid. So it should just be this localized area.

 

[gbent]

I'm with magnetic. Preheat and then braze. I wouldn't even consider welding 1) it is a low stress area where you need to just plug the hole 2) its relative old iron and the newer the iron the better chance of welding.

If you don't want to braze, I would feel comfortable using a high quality polymer such as Belzona 1111 with a well distributed patch about 1/4" thick.

 

[Jim_Lou]

What magnetic said. Or you can grind clean and sweat-solder a piece of copper sheet over it, but that would be of marginal strength for the application, I think.

 

[Timw]

I would investigate further, it looks like cast steel to me!!!!
A lot of the old iron was cast steel and you can just weld it using the normal precausions for warpage.

 

[Hanz]

It's not a workhorse out in the field every day right? I would go with the least intrusive method- one of your 'cold' repair suggestions. Last thing that you want is applying heat and having it cave in leaving a three inch hole. Remember it rotted because of rust, you can't weld or braze to rust

 

[crossthread]

I would try a cold fix first. I would not want to be welding that thing just yet. As you say it is a low pressure system and it seems like some sort of expanding plug or something would be adequate. Maybe you can clean it up and make it round with a Unibit and then use a toggle bolt to hold a rubber patch with a big washer on the outside.

 

[matt_isserstedt]

I think you can braze it with a standard flux coated rod. If you have access to the inside a flanged slug would help against any possible blowout. I would use the gas grill as a method for preheating it just to make things easier. Could be just a thin spot in the original casting.

 

[cmccull166]

For that JB weld its as good to new as it gets for instance, a 1/4 hole developed thru the bottom of my large shop compressor due to corrosion.

I let the tank dry as much as i could and used a small dremel to sand the surrounding inside areas, lots of fast drying thinner to remove any oil,squeezed in an amount of JB through the hole, I used a wood screw just to partially fill the gap.and let gravity do its thing.

8 months and counting. I feel this is a rather "extreme" fix for JB being under lots of pressure,heat ,cold,moisture etc

 

[seiner]

For that JB weld its as good to new as it gets for instance, a 1/4 hole developed thru the bottom of my large shop compressor due to corrosion.

I let the tank dry as much as i could and used a small dremel to sand the surrounding inside areas, lots of fast drying thinner to remove any oil,squeezed in an amount of JB through the hole, I used a wood screw just to partially fill the gap.and let gravity do its thing.

8 months and counting. I feel this is a rather "extreme" fix for JB being under lots of pressure,heat ,cold,moisture etc

While I applaud your resourcefulness this "repair" sounds a lot like something called a BOMB. Please review the consequences of that tank blowing up and consider replacing the it.

Epoxy would probably work fine but I would braze or weld up the hole in the coolant reservoir.

 

[CalG]

Gee,.... The J-B weld repair sounds much more like a rupture disc (a safety device) than a bomb!

It's easy to draw on the dramatic. Myself, I have NEVER seen an aged and rusty pressure vessel "Blow up".

pinhole Leaks, small ruptures, etc, yes, Catastrophic blow outs?.... Not in my experience.

If you have had direct experience of a "low" pressure vessel (<200psi) failing dangerously due to rust or pitting, please share details. I tend to be a bit bold but also strive for self accountability.

 

[seiner]

I haven't experienced a pressure vessel failure, pretty sure that I don't want to. The rupture disc theory might work, maybe. I guess what I have is what my Mom always called a "highly developed sense of self preservation". not counting scars of course.

edit: there was a thread on here a while back about a air compressor failure in a small shop or garage. nobody killed but messed up the shop badly, pretty neat photos.

 

[davycrocket]

Hi Catman

How about filing the hole to make it a nice elipse.
Then you make two steel plates, also eliptical but bigger than the eliptical hole but just small enough on the
minor dimention such that it goes through the hole when offered up to the major dimention of the hole .
Drill a hole in the centre of both the plates, and fit a hex headed bolt with the bolt head welded all the way
around to form a seal on the rear of one of the plates . This plate with the bolt attached will end up inside the tank .
Cut two ROUND rubber washers just a little bigger than the plates and make a hole in the centre of each .

Assembly....
Place a rubber washer over the stud, offer the plate into the tank.
Without dropping it !!, add the second big rubber washer on the outside of the tank, the second plate and finally a thick tight fitting small rubber washer, a small metal washer and a suitable nut .
Line up the eliptical inner and outer plates so the hole is completely covered and tighten the nut , holding the stud to make sure the inner plate does not rotate out of position .
You could make a tiny notch with a file on the end of the stud so that you can keep an eye on its rotational position relative to the hole in the tank. Hopefully the tight fitting small thick rubber washer under the metal washer and nut should seal to the thread of the stud when the nut is tightened .
"Belt and braces" would be to put a rubber sealant on all mating faces of the big and small rubber washers before the nut is finally tightened . Hopefully, the seal will be made at the inside rubber washer and the stud should not get wet, so the outside small rubber washer is yet another pair of braces! .

Davycrocket

 

[bhigdog]

Start with the least intrusive/destructive fix first. You can always escalate but it's tough to go back. Like they instruct doctors "First, do no harm"...............Bob

 

[mark costello]

Whats the second thing they teach the Doctors, grab the wallet?

 

[bhigdog]

No. To describe excruciating pain as "some discomfort".......................Bob