I hope this is the right section for this question...

the good: My 95 4runner has 167K miles on it, running like a champ. The water pump is new with 2k miles, the timing chain is new with 1k, and the front main seal got "shimmed" to fix the leak from replacing the timing chain about 300 miles ago.

The bad: The valves (or one of them) are making a tapping sound, but my mechanic thinks they should be able to be adjusted back into good shape. The real bad: My rear main is leaking like a sieve, and this is a new development, very new... Don't know where it came from, but all of a sudden I'm losing oil like it is going out of style. I went from not adding but maybe a half-quart between 3k oil changes to dropping below the dipstick within a couple-hundred miles. The estimate to fix that is around $600.

Now, the history of this engine is that it has been well-maintained as long as I've had it, with a couple of episodes of overheating a few thousand miles ago when I had some radiator issues, and one episode a couple of weeks ago when I unknowingly blew a belt. I watch my guages pretty closely, and it never really got "smoked" when overheating. Just enough to make the radiator cap sing a little.

So, the big question here is what do I do with this engine? I love my truck, it has so much stuff going for it, so I'd like to keep it until it falls to dust. Should I go ahead and fix the rear main leak, and hope it goes for another 150K like that? Or is this a symptom of an otherwise unhealthy engine that is needing rebuilding/replacement? Between doing the valves and the rear main, I'm pushing $800 in upcoming work, and that would go a big chunk of the way towards a new engine. On the other hand, if fixing the rear main will bring it back to its pre-leak oil consumption level, I would be happy as a pig in slop. I guess I'm just concerned that my last little overheating episode did some real damage.... But it still isn't smoking, like at all.

Am I worrying to much about this? Should I just replace the seal and keep on trucking?

 

Just listened to it again, and it sure seems like it has a lower-end knock too...

now what?

 

rebuild time!

i'm in the middle of one(just waiting for my block and crank back from the machinist and i'll slap it back together). it's a VERY straightforward engine to rebuild, the wiring is the worst part, and even then it's not too bad at all(tip: remove the upper intake/throttle body and unplug the sensors from the engine, starter and t-case/tranny switches, and get it all out of the way). you can do it right for under $1000 if you're thrifty, but budget out about $1500 to be safe.