How do you repair the valve seals in a 1994 Mazda MX3?

Answer

The (less than helpful) answer that I've seen for this one is once the hydraulic lifts go on the valves, it's cheaper to buy a rebuilt upgrade-spec (KL-DE or KL-ZE) engine than it is to service just the valves alone.  Having the valve cover gaskets replaced (due to oil leakage, which of course happened again after not too long) was over $800, so that gives you some idea of what doing that, PLUS replacing all the hydraulic lash adjusters, hydraulic lifters, etc is going to cost... an imported KL-ZE engine that I saw on ebay from a reputable import engine dealer, ran $1000 a couple of years ago (don't know if you can still get one), and gets you the same or better mileage, and nearly 200hp (instead of the 135hp the stock engine gets), and the only challenge is the replacement (a few quirks, like 5 relatively minor modifications from putting a stock engine in and out) and making sure you get one with the curved neck (Millenia) intake. 
Not helpful, but honest, if you want the details to overhaul the valves though, check the "Online Shop Manual" under the "Technical" section at www.mx-3.com

First answer by ChrisTexan. Last edit by ChrisTexan. Contributor trust: 32 [recommend contributor]. Question popularity: 45 [recommend question]