Checking Pistons for cracks. Magnaflux?

[badass88gt]

Can forged pistons be magnafluxed for cracks? If not, how do you check for cracks? We're thinking its a great possibilty that a cracked piston wiped out my junk, and I wanna see if I can reuse the others if theyre not cracked.

[Blue69]

Magnaflux only works on ferrous metals(iron & steel). To check your pistons, I would recommend taking them somewhere to be dye penetrent inspected, of if you can find someone who can do it, have them x-rayed. You might have to take them to some type of industrial testing place to get that done. Most competent machine shops can do the dye testing.

[badass88gt]

Is the dye testing accurate?

[1fastdeuce]

Goodson sells a dye kit for checking aluminum,cast,brass,carbide and stellite. It is kit #AC-KIT. Their phone number is 1-800-533-8010 or www.goodson.com

[badass88gt]

Cool, thanks!

How does it work?

[markstang]

Goodson sells a dye kit for checking aluminum,cast,brass,carbide and stellite. It is kit #AC-KIT. Their phone number is 1-800-533-8010 or www.goodson.com



goodson rocks, I get a lot of supplies & tools from them. they will also help/tell you how it should work ect....

[Blue69]

Dye testing works like this, you get the part to be checked very clean(no oil, grease, etc.) The area of the part that is suspected to be cracked is then sprayed with a dye penetrant, allowed to sit for a few minutes then the dye is wiped off with a clean cloth. After this you spray on a developer(looks kind of like spray talcum powder or the old fashioned underarm deoderant spray). The developer will draw the dye out of a crack in the part and leave a red(the color of the dye) line in the developer.

Dye testing works pretty well on smooth surfaces, and in localized spots that you suspect may be cracked. It does not work very well on rough surfaces, or for very large areas. Example if you wanted to check an entire head for a leak that you had no idea where it might be, you would be better off getting the head pressure tested instead of dye checked.

In your case, checking pistons for cracks, the dye method should work well. Keep this in mind though, pistons usually fail as a result of severe impact with another part of the engine. Seldom will a properly installed piston, that has not been subjected to stress loads beyond its designed usage, fail in the manned that yours did. I would suspect that the root cause of this failure was probably an exhaust valve that failed by dropping the head off of the valve stem, either because the the valve was defective, or some other force acted to cause the valve to fracture at the stem(valve float causing piston to valve contact, or possibly the valve guide and seat not being correctly machined causing the valve to flex at the head and eventually fracturing. With as much damage as was done to your head, it might be hard to tell what the exact root cause of the failure was. You just have to fix it and hope for better luck next time.

[badass88gt]

We're thinking it was a piston tore itself up, probably cracked underneath from previous piston to valve clearance issues, bent every valve a few months ago.

[FURO RACECRAFT]

I have used that dye an developer method at the railroad on locomotives. That stuff is very good if used correctly. Must be clean!!