Cast Iron Cylinder Leak Koken Chair

I would steer clear of welding unless you can get it done by a shop that is competent in cast iron repairs. Any attempt to weld it without first heating the entire part to the correct temperature (around 1500°F), followed by correct cooling, will likely result in a worse crack as the part shrinks back to size.

The reason for this is that the yield and tensile points of the metal are so close to each other that the part can quite easily reach its tensile point and so crack before reaching the yield point which would allow the portions around the weld to stretch to relieve the stresses of cooling. This would be of particular concern if, as you claim, the repair is near the flange as the extra metal of the flange area would confine uniform expansion

JB weld as suggested by SE would be a good choice if you can apply it to the inside of the cylinder. A bit of grooving and thorough cleaning of the area to achieve a good key, maybe even enlarging the crack slightly to get good filling with the glue.

If you can't get to the inside, then grooving and gluing followed by some form of mechanical cover on the outside to retain the repair may be necessary.

The crack will be polluted with oil, so thorough cleaning to a reasonable depth will be essential whichever way you choose to go with the repair

I have no idea of the pressures to be contained, but I assume they are not all that high.

Dry Sand Magic for Cast Iron Welding of Large Pieces

I have successfully welded multiple broken off exhaust manifold bolt "ears" back on a V8 block and its exhaust manifolds. I used the rectangular cross section cast iron welding rods, cast iron welding flux, and lots and lots of dry quartz sand. I bolted all mating pieces together and tack welded all of the pieces not held in correct alignment by bolts. After light tack welding I would beat and pry all fragments into as close to perfect alignment as possible. I would V-groove grind all cracks to within 1/8" of the overall thickness. I used a chain hoist to an intact bolt hole to support the assembly for upward access to all the grooves. I used the torch in a sweeping pattern to pre-heat all of the parts until I could easily feel the heat at 1" spacing to my fingertips. Then I added thoroughly dried(in a cooking oven) and warmed sand to a stock tank container until the remaining breaks to be welded were just short of being immersed in the sand. I would weld the lowest joints and add sand until all the joints were welded and immersed into hot sand. I kept adding sand until the entire assembly was immersed. Then I went away for two days to let it all cool very slowly. After the two days I chain hoisted the assembly out of the sand. I used a tiny die grinder (Dremel with 420 grinding wheels) to grind away all tack weld protrusions. I ground off all irregularities on the backs of my grooves then turned it all over to the mechanic to reassemble the engine. The engine worked great and there were no exhaust leaks. None of the cracks had extended into cylinder walls or any other critical locations. All of the detractors had predicted utter failure and had predicted new cracks after complete cooling and operational thermal cycling. The engine went back into service powering a boat I/O drive and for at least two heavily used summers had no issues. The running boat was sold by its owner after the two seasons so no additional history is known.

In the above I have simplified the description to reduce confusion. In the real process I actually bolted and unbolted various pieces to do partial welding in advance to achieve perfect alignment and not weld sub-assemblies to each other which should not be connected. In every case the pre-heating and sand cooling for two days were used. The main thing is that some welding needed to happen in surfaces held in contact when bolted. The welding and grinding of these surfaces required more care than exposed surface welds which did not need to mate with other surfaces. The complete task was achieved in one off season for boating even though there were lots of periods of waiting. The actual working sessions were not very long except for the pre-heating which took a fair amount of gas and time but could easily be delegated to welding helpers without special skills. Final mating surface grinding was tuned with carbon paper marking of the mating surfaces but was not really very difficult since near perfect piece alignment was always achieved in advance by bolting and exposed surface butt welding.

I am not a professional welder but I had taken some oxyacetylene courses at the local community college where we had practiced cast iron welding on some brake rotors and small cast iron stoves. I merely scaled up the techniques to engine block size to repair the boat engine. The boat owner had been turned down by multiple local professional welding shops who were all afraid of cracking so he eagerly allowed me to take a shot at it and was quite happy that he did. I got to do a lot of water skiing behind his boat for two years as a reward so I was also happy. None of the professionals were considering using the sand immersion despite understanding that thermal expansion issues were at the heart of their cracking nightmares.

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thewildotter

Good to hear that there are still some true craftsmen welders out there that appreciate the stresses created during welding.

No one would throw boiling water on an ice cold 0 degree F window,knowing it would shatter.

This is only a 180F temperature difference creating these stresses.

Imagine the stresses created when there are thousands of degrees differences in temperature?

Most welders do not consider this fact.

When I braze cast iron,I preheat,using Tempilstick crayons to get precise temperature.

700 F has worked fine for me with no problems,but temps can vary a little with no problem.

It is important not to overheat the iron and melt the metal,because carbon will then become a problem during cool down and will come back to haunt you later.

Small pieces I use my torch,large pieces I use a gas burner salvaged from an old flue-cured tobacco barn.(8 Inch diameter circle,72 holes-30,000 BTU uses LP.Cheaper than acetylene).

I pre-tin the pieces with brass if they are separated,before the finish bead is applied.

If the crack is within a larger piece,I drill a hole at the ends of the crack to prevent re- occurrence of the crack and of course,groove out the crack,careful to leave a rounded bottom in the groove.A sharp V groove will create a stress riser.

I tap on the area around the brazing to help relieve stress and always slowly cool.

I have a fire-brick lined cooling oven surrounded by sand and fill in around the piece with hot sand.

I let it cool naturally which can take a few days for a large part.

Slow and steady wins the race.

As said elsewhere you need to follow the correct preheat which can be done if you have a decent burner and a digital readout and thermistor, you just have to get the heating even.

I have used CIG/BOC Castcraft rods to repair cast vices in the past and the rods are easy to use but the weld material is very hard to grind.

Post cooling has to be done either by burying in dry sand or lime which has been heated to dry it out. I have an old AJS motor cycle engine with a cast iron head and it has been brazed so that is another option either brazing or silver soldering.

If you don't want to weld and you can pull the cylinder apart then a thorough clean, I find break cleaner or lectra clean excellent.Then apply a vacuum to the cylinder and smear epoxy to the outside and allow the vacuum to draw the epoxy into the pores. Warming the cylinder will decrease the cure time and thin the epoxy down so it flows more easily.

I had a set of mag wheels way back in 1970, which leaked through the casting and the remedy for that by Goodyear was to coat the inside with an epoxy sealant but then the pressures would have been lower than in a chair

Impossible does not come with a time frame. Claim the warranty or replace the unit with another manufacturer.
Cast iron of today is much different than cast iron of old. Shop for a replacement.

Great that you got it fixed and can now return to being the chair man, a cut above the rest!

A friend of mine works with a company that specializes in fork lift repairs and manufactures pieces for the same. They have a person who specializes in cast iron repair . The part was welded and heated and cooled properly. Hopefully it is fixed.

The barber chair cylinder is subjected to very low pressures . It is an open system not a traditional hydraulic cylinder. Oil is simply poured into top of the cylinder. The cast iron piece is nothing more than a big cup to hold that oil

I was going to second Solar Eagle's reply because I have repaired a tractor loader hydraulic cylinder with JB Weld.

However, It's awesome when someone gets success by doing things the right way.

could have saved a lot of time if you gave full disclosure originally.

The fix would have been to de-grease using something like simple green (great de-greaser btw), JB-weld the crack, and then coat the interior using 100% silicone sealant.

What do you mean by full disclosure ? It’s a cast iron cylinder from a 100 year old barber chair that had a some sort of defect which caused it to leak.A picture of the leak included for reference . Please let me know what I left out .

well its basically a cast iron oil tank. i was under the impression that it was a hydraulic pump which was to support pressure.

sorry my bad for assuming.

by full disclosure, one would state what the part actually does, in this case contain oil, nothing more.

One might wonder why Koken chair repairs seem to come to CR4. when other websites are available.

Does that mean this is a duplicate thread?

This repair is not specific to the workings of a Koken barber chair