Coincidentally, I just finished pulling the cylinder heads off my '95 4Runner today. I also had a #6 failure from the coolant passage to the cylinder. The gasket was pretty much gone there with exception of the fire ring. Toyota also claims my vehicle is not included in the recall either. Interesting, it has the same mode of failure. I'm fixing it myself, but I'm still going to send them a bill to cover parts just for kicks!

My issues started quickly and went from a miss at higher RPM's, to a check engine light code 25, to puking coolant out the overflow reservoir and overheating, all within a couple days.

Coolant can and most certainly will leak into a cylinder if the gasket fails, and in some cases causes hydrolocking of the engine. When the engine is off, coolant drips into the cylinder filling it up. When you start the engine, coolant blows out the exhaust, and there will probably be a miss. If there's enough water, it can't get out fast enough and will bend the connecting rod (or worse). When the engine is running, the force of combustion forces air in the reverse direction through the leaking gasket, and air gets pushed into the cooling system. It will, as in my case, push air into the entire system forcing coolant out the overflow reservoir.

I figured out how to do my own leakdown test to verify which cylinder(s) had a blown gasket. I have another post going in the 4Runner forum about combining a 2 gallon air compressor with a compression gauge to make a makeshift leakdown tool. I used it to pressurize the cylinder in question and see if I could force air from the cylinder into the cooling system. Glub glub glub glub was the sound I heard when I tried it on good old # 6!