Part of our beloved hobby is the restoration/maintanance of the aged & tired vehicle. Just recently we have started a series of repair samples under the name "PreWarCar Workshop". In this week's Workshop
we like to show you the problem with cracks in cast iron.
Say, you've got a special car. Only a few still exist. And then you find out there are cracks in your cylinderhead. That can be quite a problem if the
material is cast iron. Welding the 'normal' way is difficult and sometimes nearly impossible. And to have a new one cast is very expensive. One of the options is to braze it with bronze. A decent procedure for certain parts. You first drill a small hole at the begin and end of the crack, make a V-shape in the crack, clean it, heat the material until it is red hot and then let the bronze flow in the crack. This is good for some cracks but not strong enough for all repairs. I had this problem with one of my cars and found a
company called Cast Iron Welding Services ltd. close to Leicester, UK. The name says it all. The only thing they do all day is repairing cast iron. The way they weld is different from most other welding methods and it looked very simple (but isn't that always the case that things look easy when a craftman is doing his thing...!).They start with cutting all the bad areas from the cast iron. The missing bits being replaced with inlays of newly cast iron. After cleaning, a furnace is created around the part with bricks and a big heater.
The furnace will burn for a day and night, so the complete part is the good temperature for the next step. The welding itself is comparable with the bronze blazing . A torch to heat even more and let a cast iron rod flow in the cracks. The material becomes one and is as strong as the original cast material.
After machining it is nearly impossible to see where repair and original meet. But more important, the cylinder is usable again (they even offer a 12 months warrenty) .If you have any experience with repairing cast iron, or you have another interesting subject for the Pre-War Workshop-section, please let us know!
(photos courtesy Cast Iron Welding)