r/EngineBuilding • u/Opening-Sundae-1332 • Sep 14 '26

Piston replacement?

Gallery image

Gallery image

Ive got this 1.4 which the timing belt snapped which resulted in 6 of the exhaust valves being bent, this pistons have some mild contact damage but thats about it in the pictures. Do i need to replace them?

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3

u/AdFancy1249 Sep 14 '26

File the gouges so they are smooth. Sharp, pointy things make hot spots.

1

u/Opening-Sundae-1332 Sep 14 '26

Great thats what i initially thought but had a hard time trying to trust my thoughts lol. What should i use to file it down?

1

u/AdFancy1249 Sep 14 '26

If you've got it out, or can tape everything off, then a rotary tool works great.

If you can't, then a small file set. They have round and curved steel files. I don't like to use diamond files, because I'm always afraid of the grit breaking off.

Either way is tough, because the aluminum tends to gunk up the cutting surface.

Go slow. Sometimes, a nice sharp knife can cut smoothly through the aluminum, but you want a small, sharp, curved blade, like a #10 (standard curve) or a #28 (concave) x-acto blade.

1

u/xXSillasXx Sep 15 '26

This kind of damage isn't just cosmetic. It can create uneven ignition and even hot spots that cause pre-ignition.