'90 Celica Smoking From Under the Hood...

The front of the engine is actually on the right side (from the passenger's view) of the car. When you say "front," assuming you mean the side of the engine closest to the radiator, you are probably seeing a lower radiator hose leak. The lower radiator hose runs from the block to the bottom of the radiator.

Also check, im not sure if the non-turbo has it, the oil cooler coolant feeds. Theres a "hose from hell" (two on the turbo) that is a short curved (and impossible to get to ) hose that feeds the oil filter location with coolant. About this age this splits and dribbles down the exhaust side of the block and all over the exhaust. If you need pics i can supply them. Check for water to the sides/below the oil filter location. The lower rad hose, as Ray mentions, goes in right next to the oil filter but below the alternator.

This sounds about right, excellent guess on your part (both of ya).

...but i'm having a hard time seeing into that location without pulling everything off... a photo would be very helpfull, thanks Coyoteboy.

The easiest way to find the leak is probably from below. If you are going to attempt to repair the leak yourself, the plastic shields have to come off anyway, and it is just a matter of removing some 10 mm bolts.

...and hoping they don't

Lube them liberally a few days before hand; the best I have found is some spray lube from GM.

Ah, true... i neglected to mention that i was already doing that, but i could see from what i stated how it was not clear.

What was making it difficult to see where the coolant was coming from (for me, anyway), is that it seemed to come from the engine block itself. When i squeeze the top radiator hose, you can watch it trickle out from a circle in the block itself just to the left of the oil filter.

Showed this to my brother (who is vastly more experienced in such things than i am), and he instantly said "freeze plug". What's more, if it was cracked enough to let coolant drip out with just squeezing the hose, then when the cooling system was pressurized, it would pump the stuff out like a lacerated femoral artery. I then reasoned that it was in just the right position to spray into / under the exhaust manifold and its heat shield, producing the smoke. I then pointed out a crack in the manifold that i noticed, right where the coolant was spraying into it. We both decided to table that issue until the freeze plug was taken care of.

So what do you guys think? sounds about right to me. He suggested not doing this in the street (i have on street parking only), and that even with his tools and experience, he hadn't the time. Given my tools and experience, this should be a shop job only. I'm guessing he's right about that, even though i have basically zero funds.

Does this sound about right? Any ideas how hard / expensive of a repair it might be? Thanks for the advice so far.

Sorry, I am a terrible mind reader ;-)

A circular plug in the engine block about 1 inch in diameter is commonly referred to as a freeze plug because the conventional wisdom is that if the coolant freezes, the plugs will pop out instead of cracking the block. if the coolant freezes solid, there is a very good chance the freeze plugs will pop out and the block or head gasket will develop a leak. Those plugs are actually used to fill holes that are left from the casting process.

If there is a couple of feet of clearance next to the leaking freeze plug, you can use a slide hammer to pull the old one out, and replacing it is a matter of finding a round driver about the same diameter as the plug to drive the replacement one in. A deep 1/2 inch drive impact socket works well as a driver. If you do not have good clearance next to the leaking plug, then getting the old one out can be a major hassle. If it is behind the exhaust manifold, then it has to come off, which can be a project on to itself. If the manifold has to come off to get at the freeze plug, I'd take car of the cracked manifold at the same time.

The job is more labor intensive than parts intensive. The replacement plug is relatively inexpensive, but it will take a lot of time to get the old one off if it is in a hard to access location. This can be a 3 or 4 hour job for a pro.

It sounds like the coolant spraying onto the manifold is what cracked the manifold.

Now here's an interesting development:

I drove it to a repair shop that my brother recommended (or so i thought). Evidently, there are two places with nearly identical names near each other on the same road. I parked the car (after stopping several times, and adding water to my uncapped radiator) in the wrong shops lot.

I called this morning and learned that it was the wrong shop, and went to move my car to the other lot tonight. it's only two blocks, and again, i left the radiator cap off, and refilled once in route. No overheating.

What i noticed, however, really surprised me. Not the freeze plug... nothing different about that, but the odometer read 205,000 miles!

Is it even remotely possible that *i* accidently messed up the odometer by 10,000 miles?

I'm really surprised...

No. That would take disassembly of the dash to do.

Few recent steamy bonnets have come from bad rad caps, for anyone else with similar symptoms - freezy plugs are very rare unless you have had very cold weather or dont use anti-freeze.