After doing my once every-other-year coolant flush in my 86 runner last month, the coolant bottle has continually but slowly been losing coolant so it's near the low end rather than between low and high like it normally was after each week. As usual, I used Toyota red, 50-50 w/ distilled water, drained the block, etc. The only thing I touched during this flush was draining the radiator and block (flushed w/ distilled water, drained again, flushed again, drained again, etc.).

Then while on a road trip a week ago and after having driven only a few miles on a cold engine, I noticed coolant dripping at the gas station. I wasn't able to find the source of the leak other than the alternator was wet. After driving a few hours on the way home, I checked during a rest break and there was no sign of any leak. Ditto with every day after reaching the office (20 mi each way). Inspection revealed no stains on the block or head, no stains around the water pump. Both water pump, HG, radiator, and all radiator hoses were replaced 55K mi ago when the t-chain was done (there was no real need to do the HG for the t-chain only, but I had a new cam installed). All parts are OEM. Also, no sounds that would indicate failing water pump bearings, engine oil looks normal.

Then today, it started dripping only after a short, 2 mile trip. I finally saw the actual drops...coolant dripping down from the area of the upper radiator hose (the one that goes into the engine from the bottom of the radiator. When looking at the alternator from the driver's side of the engine compartment, there are two places on the top of the alternator where you can see the copper wires inside. The right (or rear most) place where you can see the copper was where coolant was dripping into, about 2 drops per second (so kind of fast) straight down into the alternator. While driving, it appears the fan flicks the coolant around so it mostly strikes the plastic steering u-joint guard, but the stains show the coolant drips onto the alternator, then onto the driver's side bolt of the steering stabilizer (and some on the pitman arm, maybe being blown by the fan). The stainless hose clamp is tight. Where the drops are falling is about 2" from the actual head, so I don't think it would be a HG weeping and dripping that far away (it would probably run down the head/block and leave a tell-tale stain). After the engine is hot, it doesn't seem to leak.

Also, the engine runs cool as normal (temp gauge is about 30-40% from the cold mark at operating temperature), so nothing indicates overheating...just a leak. I don't, however, understand why it would leak when the engine is cold, and not while hot (it did start leaking a little for less than a minute after I got home from a 1 hr drive today..first time I've seen it leak after the engine was at operating temperature, but wasn't leaking after the initial 1 hr drive out to the trailhead). The only thing I suspect (and hope it is) is a leak in the upper radiator hose above the alternator. But if that were the case, wouldn't it leak all the time? Would anyone have any opinions/experiences that would support or repute my guess, and that it was something more serious like a HG? How about the aluminum male end where the upper radiator hose plugs into the engine above the alternator? Is that part known to crack?

Finally, if it is the upper radiator hose, I'm wondering why it would only last 55K mi while the original one went much longer? Maybe it has something to do w/ excess heat from the LCE header that was also installed 55K mi ago?

Where the hose connects to the water pump is directly over the alternator. It can be a PITA but I would try to loosen that clamp, move the hose a little bit, then retighten the clamp.

Do you think it's the hose leaking or something more serious?

Im working on a 22re, and its all taken apart, except the hose he's talking about. It is like directly on top of the alternator. It could just be that the clamp is kinda loose or the hose has a small tear in it. I dont think it's some crazy thing. At least it's not mysteriously leaking somewhere you cant see it (ie engine block like mine)

There is also a heater outlet connection on the back side of the main hose on the water pump. It is kind of hidden as it connects to the back of the timming/water pump cover.

But if that hose leaked, wouldn't the leak be internal (inside the timing cover), and you'd get coolant mixing w/ oil?

My plan was to take a reasonable gamble that it's the hose above the alternator and to just drain the radiator, pull that hose and replace it. Cost would only be the cost of the OEM hose plus $15 for a gallon of Toyota red. The clamp is tight, but it wouldn't be beyond belief if the leak was still in the development stages and it occurs near the hose clamp. If it still leaks afterwards, I'll probably have a compression test done or something, but the $30 to replace the hose and refill the radiator is pretty minimal (and since I just replaced the coolant a month ago, I guess I could attempt to recapture the coolant into a clean plastic jug and reuse some of it?).

No problem re-filling with the existing coolant. I have one hose that leaks just a bit, but it is going on 6 years old and I have new hoses to install. I try to replace all of mine every 5-6 years, keeping the old hoses for spares.

Well, 5 yrs is 60K mi, and that's how many miles I have on these OEM hoses despite them being only 3 yrs old. I do live in So. AZ, so it does get pretty hot here, plus I'm running a LCE header. Maybe the heat deteriorates the hoses faster?

how's the weather like down there right now? I'll be visiting some friends in tucson this weekend. yeah, I could be cracking maybe...

Not bad. It's been hotter than normal lately, like 85-91F over the past few weeks (except sat. night and yesterday...rare rain). I'd guess upper 80's. I'll try replacing the hose on friday.