There are two local machine shops that can work my cast cylinder heads. Both will mill them if warped for 30 bucks a piece. But to crack check, one uses magnaflux at 3.50 per cylinder. The other will "water tank" them for 30 bucks per head. (I think her called it presssure testing.) He said on the water tank they submerse them and look for bubbles and it will tell if there is a crack inside the head as well.
Is there a big difference? Magnaflux is cheaper I guess.
Magnaflux will find cracks that don't leak *yet* or only leak when hot, tanking won't.
Tanking will find leaking cracks that in passages you can't see into, which may be significant or not depending on how open things are.
That'd be my take, anywhoo.
Dave
No simple answer to this one.
Magnaflux will show cracks that do not leak, and will not tell you if a certain crack will cause a leak.
Ideally the best answer is do both, but the price sounds high.
A savvy head man can use Mag, and probably tell which cracks will cause a problem (or are acceptable), and which will not. But they are often very reluctant to do so. No one wants to rebuild and resurface a head on to hear later that it leaked, in which case everyone loses.
My preferred method is vacuum checking, scrapping anything that leaks, who cares where? - and Mag checking to examine all less significant cracks on a case by case basis. I would rebuild heads with cracks depending on how severe. Many heads are needlessly scrapped DAILY, because shops don't have the right equipment and expertise. Look for a shop that can vacuum and Mag. Prices should be $25 each or so.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.