Cracked Heads

[Alias]

Why is it an engine will run fine, and when you decide to rebuild it for whatever reason and have the heads magnafluxed they sometimes come up cracked are are no longer usable? Why were they fine before and now are no good?

[Racing Ray]

How many people rebuild an engine that is running fine???

[Alias]

Ok it runs fine, but I want to punch it out a little, or smokes so figure I'll re-ring it, valve job, new cam, head gaskets?
[This message has been edited by Alias (edited September 07, 2001).]
[This message has been edited by Alias (edited September 07, 2001).]

[Racing Ray]

Heat causes metals to expand. So what is now a small crack and not causing a problem suddenly opens up more leaking water into the cylinder and causing it to fill with water. Now that you have a large hole in those new pistons and those rings and head gaskets are toast not to mention you just wasted all your money and will probably even need a new block. Now who are you going to blame?? Why naturally the fellow who told you to replace those heads because there is a crack in them.

[Havasu Hangin']

I've always found that wearing a helmet is the best way to prevent a cracked head... http://www.goldenplasma.f2s.com/forum/smilies/happy07.gif
However, I have to agree with Ray. I used to work in an engine rebuilding shop when I was a kid, and my job was magnafluxing and valve jobs. You would be surprised at how many iron heads had small cracks. Sometimes they would be in a place that showed (water jacket, etc.), and sometimes not.
http://www.goldenplasma.f2s.com/forum/smilies/happy25.gif

[Squirtcha?]

There is a sequence for torqueing head bolts. The same sequence (in reverse) should be followed when removing heads or they could crack in the process. Remove bolts from the ends working towards the middle and alternately back and forth in a criss cross fashion. It's possible that you cracked them yourself when you removed them.

[Alias]

I'll believe that. thanks