Air/Fuel ratio lean and other problems...

[tre_03]

Hey guys...just a quick question about my 1993 Toyota Tercel. The check engine light is on and giving a code 25...air/fuel ratio lean. Does anyone have any suggestions of things to check? This car has been giving me a lot of trouble lately, and this is just another chapter in the saga. The thermostat housing started leaking and essentially bled all of the coolant out. I'm not sure if this a Tercel "feature", but there are no indicator lights on the dash that light up when the car is beginning to overheat. I noticed the car was idling high in a drive-through and looked down to find the heat gauge needle pinned to the top of the red. Not very good. I took care of that problem, but shortly after it began pouring thick white smoke out of the tail pipe. Blown head gasket, cracked head, or cracked block. Since there was no oil being burned and no coolant in the oil, I took "cracked block" off the list. I used a couple of "quick fix" additives that are meant to seal cracks in head and blown gaskets. After I tried a couple of brands the leak was completly gone. Well, as luck would have it, I had another over-heat. It turns out that during the whole ordeal the radiator developed a crack where the hose attached and was spraying out when it was at high pressure (ie. while I was driving). I fixed that problem and tried the additives again. No luck. I replaced the head gasket and saw the old one had a pretty substantal tear in it. Cool. A new head gasket will fix my problems. Well...not exactly. Still smoking out the back (only not as much), but the coolant (actually water right now) is still "disappearing" causing the tempurature to rise. It hasn't "overheated" yet with the new gasket in, but it does run hot and would overheat if I drive it very long. I'm in the process of repeating my additive experiment that worked last time, and then the engine code started. Maybe related, maybe not. Any idea about the code? And suggestions for sealing the leak? A new head or new engine just isn't an option for me right now. Any help would be greatly appreciated.