All good advice above.
My recommendation is a bit different, though.
Take your last penny to the bookstore and buy Nigel Calder's Marine Diesel Engines.
At Amazon, it's $18.45 new in hardcover or $13.14 used.
Amazon.com: Marine Diesel Engines: Books: Nigel Calder
It's the best investment you can make to keep your Isuzu diesel humming.