Hey, I'm new on the board. Trying to get my Wagon back on the road, here's a lil back story.

She overheated on the interstate a couple months ago. Headgasket failure... boo. I take it apart, and see these pics.

No damage on any of the valves on the head, but there's a dent in one piston, and the back piston has the funky abrasive surface on it. I put the head back on, hoping the dented piston would still seal... it didn't. 120-130psi compression on the 3 pistons and 0 on the dented one. I still don't know how it got a dent in it. The gasket overheated on the back piston that has the corrosion on it.

So. I need some help. Can I just buy a used piston, put new rings on, drop the oil pan, unbolt rod and piston, put new piston on old rod, and bolt it all back together again? I need to do this on the cheap, and that's the only piston giving me problems. Thanks in advance for your insight!

 

You need to replace the piston. They come in a set of 4 and you should replace them as a set.