It also has a small chunk taken out of it near the base. All 8 pistons have light pitting like the one in the pic. But not so much that I can feel it under my fingers. Should I try and save my calipers with a seal kit or just buy new ones? Seem to be getting mixed opinions on whether or not I should. Reason why I'm trying to fix it is because one side was hanging up and causing brake drag. Also lose a bit of brake fluid over the course of a few months (slightly below max), but no signs of visible leaks anywhere.

 

The pistons really don't have much to do with what's really going on. What do the caliper bores look like???

If the bores are smooth and clean, the calipers will likely work well with new rubber components installed, even if the pistons are a little rough.

Given the vital importance of good brakes though, if you have any reservations at all, go with the new calipers.

 

The bores are in a lot better condition. I actually had a hydraulic mechanic friend who told me those piston were junk so wanted a second opinion on that haha The truck is more of a bush rig so if they end up leaking it's no big deal, I can just replace when convenient.

 

I can understand working on hydraulics for a living I would also say time for new pistons .

It is a mind set you get into better to replace it now then get called back next week.

For your caliper most likely it will be fine for quite some time.

 

I'm pretty sure the pitted surface has nothing to do with the brake operation. The seal is by the "rubber" component, the piston just holds it in place, so the only part that matters is the groove. (But then, how would a piston get a chunk knocked out of it?) The caliper repair kit runs $5-$12 at RockAuto, and a caliper reman'd by someone other than you is $40-$50. Your time is worth something, and so is your peace of mind (it's not obvious on that second part whether DIY or reman is better)
Are both pads wearing evenly? Just one? Is it worn at an angle? If just one pad (or uneven wear), I would look closely at the guide pins. Very simple, and easy to replace.

 

When I changed the pads and rotors they looked pretty even but Ive only put roughly 1000km on the new brakes since this truck isnt a daily, more of a bush rig/project. But they look pretty even so far.

As for the chunk, there was quite a bit of sand and what looked like water in there! Surprised it wasnt more rusted than it already is. Cylinder bores in good condition though, much better than the pistons. I did flush the brake fluidnat one pojnt but I guess all that junk must have accumulated at the bottom of the caliper.

I'll put in that seal kit and keep an eye out for leaks and fluid level. If I need to replace the calipers later on I wont be too upset anyway.