Full story. I took my disco into a jiffy lube to get the oil changed. The next day my coolant res. was bone dry. I let it cool and filled the res. I wondered if this had anything to do with jiffy lube. But figured it would be the end of the problem. Nope. Over the last couple of months it has been going through fluid like crazy. I have just been using universal 50/50 coolant. At one point about a month ago i called jiffy and asked them id this would have anything to do with them and of course they said no. They told me i could bring it in and they would check it out free of charge, so i did. They said they couldnt find any leaks and they refilled my coolant and sent me on my way. I'm assuming they did not do a pressure test and they just peaked around. It seemed to be quite awhile before i had to refill the coolant res. again. Two days after refilling the coolant i was at the dump when I noticed coolant spewing under my truck. This was the first time I've actually seen it leaking. I took it home. It didn't go past the center line on the gauge the whole ride home. The leak was still going strong when i got home. I grabbed my glasses and rags and tried to find the issue. I couldnt pin point it then and i stopped driving it. Today i went outside and started it up to try and find it again. It took at least ten minutes before the leak started to appear. I first notice it on my front diff. and the bar in front of it. I started from the top down. I didnt notice any leaking on the res., on any hoses, or on any visible gaskets. So i shut the truck off and went under. it was dripping directly onto the bar. Right next to the oil filter? on the passenger side is the area in which it is coming from. There is a small metal pipe that the coolant is traveling down. it looks like the leak is coming from that nut attaching the pipe to whatever it is attached to?. But it probably isnt. I cant really see beyond the filter to see what is on the other side of that. I have no problem getting my hands dirty or doing reasearch but when it come down to it I dont really know what most are. I dont think its a hose or a clamp, my rad and my res, seem to be fine, I can only assume that is a gasket.
I just need some thoughts and opinions on what to check.

 

1. This has the potential to do great damage to the engine by overheating. It will have coolant loss, and then really overheat. It actually is getting hot now, the gauge is just programmed to stay in the center until it is really closed to cooked.

2. Until resolved it is a must you check coolant dialy before any short trip. Would not plan on long trip, and if you can drive something else that would be good.

3. Do you hear any gurgling water noises under the dash, like water in pipes? That would be air or exhaust gas bubbles in the coolant. Air can be purged, exhaust gas returns (head gasket). Operating with lots of air in the system can make overheat, the steam does not transfer heat as well as coolant.

4. Do you have any white smoke out the tail pipe after truck warmed up? If no, good. If yes, head gaskets could be an issue.

5. A drip of coolant at the very front of the engine can be coming from the water pump. That is the part the large fan is mounted on that spins. Leaks can come right out the center of it at the shaft, or at the back of it on gaskets. If truck is at idle, look at the pulley and belt, and see if it runs true or if there is a little wobble. Wobble is bad, fan can come apart and slice up radiator and eat hood.

6. Many auto parts loan tools with a refundable deposit. You could obtain a coolant pressure tester, which allows the system to be pumped up to say 18 PSI, with engine not running. The coolant will begin to leak out steady and will be easy to find.

6. Auto parts stores also sell small inspection mirrors on an adjustable stick, makes looking in tight places easy to do.

7. Do not assume gasket. While it could be water pump gasket, head gaskets, valley pan gasket, or front cover gasket, it could also be a hard to see hose clamp.\\

8. Cooling system layout plan attached...

 

Very helpful post (as always) SavannahBuzz. Thanks. Now I have something to do this weekend :-)

 

So its not leaking until it gets hot and builds pressure.
Look at the hoses and hose clamps, if it were a head gaskets I would think it would leak straight away.

 

Point is that a coolant leak might be an external head gasket leak. But it could be a cheap hose and clamp. Water always wins.