Overheard a welder say he never preheats cast iron and just uses nickel rod cold

Margaret Shah · 2026-04-23T21:45:03.691517+00:00

Tried it on a cracked tractor manifold last week and it held up fine, but has anyone else seen this actually work long term or am I just lucky?

troy_scott5mo ago

Bet on it cracking again down the road.

9

uma_nguyen245mo ago

Ha! @troy_scott is just jealous, I've seen cold nickel rod hold on manifolds for YEARS without issue.

4

michael_craig4mo ago

Has @uma_nguyen24 seen this hold up past a few heat cycles though? I think cold nickel rod works fine for low-stress stuff, but a tractor manifold gets hot and cools down a lot. That thermal shock is what usually busts the weld or the base metal next to it. You might be lucky now, but give it a hard season of work and I bet you'll see a crack form right along the heat-affected zone. Preheating is cheap insurance compared to pulling the manifold again. Just my two cents from watching guys try the easy way.

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