Wow, thanks for all of the help! I'm going to go out and take another look at it now, but I'll try and address everyone's comments/ideas/questions first.
Visible coolant is a fraction of the leak. With the heat of a running motor, most of it evaporates very quickly. Did you check all the radiator seams? They've been known to fail, initially it'll just manifest as hissing, steam and/or bubbling. It can be very easy to miss.
If you can't find it, carry extra water, top it off every day and watch it closely. Leaks have a way of getting bigger, then it'll be obvious. You're okay as long as it doesn't overheat.
Okay, that is good to know. I can see why it would be hard to spot radiator leaks, with all that airflow.
I've never seen coolant run out the tail pipe, just vapor.
Well, what was happening (I think) was that the exhaust pipe was cool, and the vapor was condensing on the inside of it, especially in the resonator, and then dripping out. So it wasn't running out of the engine - just condensing in the exhaust. It did glow green under the blacklight though - I got someone else to look at it just to make sure I wasn't imagining it!
You might also try using a pressure tester. It allows you to check for leaks when cold. Liquid is far easier to spot then steam.
So you are pressurizing the entire cooling system with this?
If you were loosing that much fluid through a blown head gasket, it would steam clean the spark plug of the offending cylinder. Pull the spark plugs and compare them looking for a real clean one. From what you have said, it sure sounds like a leak. The radiator pressure test kit
http://www.harborfreight.com/radiator-pressure-tester-kit-61666.html (dang, didn't know they were this expensive) is the key. Or, start it up and get to operating temperature/pressure. Turn it off. Use a glove and a paper towel, and swab under all the hoses to find the leak.
Okay, I think I will check the spark plugs if I can find a spark plug socket the right size, thank you for the idea. I'll try that with the paper towel - I'd been doing a little bit of that but I think the glove idea is a good one! So with the radiator test kit, is that the same thing BrotherRob was talking about? Do I just need to pressurize the cooling system to like ~30 psi and be able to watch the pressure with a gauge and look/listen for leaks? Does the overflow bottle tube need to be blocked up for this?
Did you ever look in the overflow bottle with the truck running/revving ? Look for air bubbles coming up.
Yes I did, thanks for the tip. I've checked at various temperatures/run times/RPM but didn't see anything. I'll keep checking though to make sure.
If you are driving it around it would be great if you can keep a scan guage hooked up to monitor your engine temps so as to prevent anything catatonic.
That was the first purchase I made for this truck (of many to follow
) and sometimes I feel I spend more time watching that temperature gauge then the road! Okay, maybe that's an exaggeration. Anyhow, as long as it's below like 90F outside, it doesn't get above 193-195. Highest I saw was 213 driving up a hill, low on coolant (didn't know it at the time), maybe 90-95F outside, and I was ready to pull over if it got any higher. I've just read too many HG threads, as evidenced by my willingness to jump to that conclusion so easily when I noticed my coolant was low.
x2 pressure tester-cold engine-coolant full-pump up to about 30psi-leave it and monitor-listen also-if it continually drops pressure (and not leaking at the cap) it's going somewhere. watch it for a few hours. Ii either will go into the cylinder or oil where you won't see it or will come out onto the ground.
Okay, cool, this seems to be the next step. Is this something you have to buy or can you just hook up a bike pump or air compressor or something in place of the coolant overflow bottle and pressurize the system with that?
I'm going to go out and poke around some more with the equipment I have currently and see if I can spot anything. Just for my own reference, coolant is ~1cm above full line in the overflow, w/radiator full and devoid of air. This is with block cool. That way I'll be able to tell if any/how much leaks out.
Thanks for all the help everybody! I really appreciate it.
