I was in the shop just messing around with some of the first housings i ported with a busted water jacket so i first tried to braze it with the heat then pull up method well...... that did no work it had a slight hot spot on the surface and when i hit it with the punch it broke right through.I then got another housing with a busted port about 1/8" and took it to the tig with a cast iron rod and did the dab and pull trick built up around the edges first and slowly built my way in. I did not see any sign of heat stress i hit it with a punch it did not move. I then ported it down smooth and hit it once again and it still held. I remember it was brought up once before and would just like to see what some of yall think
Originally Posted by FrostRacing' date='Apr 15 2004, 04:25 PM
I did not see any sign of heat stress i hit it with a punch it did not move. I then ported it down smooth and hit it once again and it still held. I remember it was brought up once before and would just like to see what some of yall think
The brazing is the oldest and most often used method of casting repair. The main problem with cast iron is that it is so brittle that the small amount of shrinkage after it cools just cracks it beside the weld. So heating the whole casting so that as the shrinkage is going on the casting is getting smaller at the same rate, so no cracking.
The braze works with less drama because it can change shape in small cross sections and is less likely to crack the casting. Also high nickle rod works the same way.
Going in with a TIG and doing just a spot at a time and letting things cool down before another pass works on some situations. The iron filler is one strategy for the little bit at a time idea. Or low carbon filler rod, like a coat hanger cleaned up, can alloy the iron in the weld area into a more malleable alloy and it can stretch a bit when cooling so less cracking.
The old standby when nothing else seems to work, is to drill out the hole to some tap size fine thread. Put a chunk of cast iron in the lathe and turn it down and thread it to a tight fit in the tapped hole. Cut off the threaded portion and screw it into the hole dry. Grind it flush and add a spot of TIG that it involves both the parent metal and the plug, to keep it there.
