I have found a potential project car being a 1987 rx7. It has a 13b crate replaced 30k miles ago but it's locked up right now. Would it be worth it to get as it's fallen in my budget of around 2k.

 

Budget at least another 4-5k for a rebuild and possible damages internals. This should be standard practice when buying an RX7, unless you personally know the condition of the internals.

 

He did investigate a bit but said he didn't want to anymore. He said it might be a seized starter or needed atf in the housings. I'm just curious what it could be as well.

 

You really won't know until you can spend some time with it. Unless the starter has seized with the gear engaged to the flywheel you should be able to take the spark plugs out and spin it with a 1/2 inch ratchet and socket or breaker bar on the fron pulley bolt to check if it's locked up. If you can't turn it, there's a good chance it's locked up and ATF isn't going to fix it. ATF is mostly to get seals that are stuck in the rotors and causing low compression to free up and get some compression back. As mentioned plan on a rebuild and replacing damaged parts. If that's not a rabbit hole you want to go down I'd pass on it.

 

Could be a few different things. At $2k, if it’s clean, it wouldn’t be the worst deal ever made. Drop the starter, put some ATF or MMO in it and spin it. It will eventually break free if its carbon seized. But not likely. Worst case scenario, you need a rebuild. Best case, you need a starter.