I'm looking at buying a used excavator. It'll likely be an older, high hour excavator since I don't have a large budget. What should I look for? Are there any particular repairs I should stay away from? Any other telltale signs of an excavator that hasn't been taking care of?
If you have any interest in driving to Southeastern Connecticut, I can show you mine. The good, the bad, and the ugly. Or if you have a buddy that has one, I think looking over one in person will be far more valuable to you than trying to describe online.
I bought a 1992 Hitachi 120, with about 4500 hours about a year ago. We are someday building a house on property up the street, with about 1/4 mile of driveway to put in.
We replaced the track chains on it, which was about 5k in parts and I did the work myself. I knew they were worn when I got it, and they could've been pushed more, but I wanted to drive it up the road to the new place, and the peace of mind was worth it. It drives and turns far smoother now.
We looked at this machine, and also a Deere 690D. The Deere was a larger machine, which was intimidating to me in the event of a failure. On my 120, I could pull the motor if I really needed to using my tractor. No chance on the Deere. Also a hydraulic pump for the Deere was something in the range of 10K, and they were known to fail.
We've been able to do a tremendous amount with the 120, and working in the woods where we are, I wouldn't want anything much bigger. So independent of condition, picking out the appropriate size machine is something you'll need to contemplate.
If you are looking older and higher hours, you're going to run in to worn pins, leaky pistons, old hoses, faded paint, some dents etc. None of those is likely a deal breaker. What you're looking for in a machine will probably be different than someone looking to make a living with it.
I'd check track chains for stretch and ensure the correct number of links, look for really bad leaks, look at the coolant, oil, and hydraulic fluid for color and contamination. Try to start it cold if possible, pick up the machine to check play in the swing bearing. Check the swing gearbox to make sure it has gear oil in it, and hasn't been packed with grease. Run it to make sure it operates smoothly and has power.