I've been a little baffled by this situation. I'm losing coolant and I have no idea where it might be going. I don't have any obvious leaks, hoses are all good. No oil in the water. I topped off about 10 days ago and checked just a little bit ago and the reservoir was dry. I haven't had any overheating problems, aside from when I discovered this situation. I was in traffic and started to get hot, so pulled into the gas station, no water in reservoir. I've been keeping up on it, but I'm getting ready to tow a trailer with the D, so I need to get to the bottom of this. Thanks-Bob

 

Jack it up, crawl under, and look for green. A leak doesn't always mean a puddle in the garage. The water is under pressure and the crankcase is not (comparatively). You'll likely get water in the oil rather than oil in the water. Change the oil and see what it looks like.

 

I did a pressure test yesterday, and it was not obviously leaking, but it did start to lose pressure slowly. There is a drip coming from somewhere on the rear of the engine on the passenger side. I can't find the source, but it drips down and drips off of the frame just behind the passenger side wheel. Any idea of what could be up in that area that could be subject to a small leak. At this point I may just bring it to my shop and ask for help.

 

There a a crossover passage running through the far rear of the intake manifold casting to get coolant from one side to the other. It's the last holes though the gasket between the head and manifold. It could leak to the rear by going through a 1/4" of bad gasket.

Pulling the intake manifold is popular to fix the plenum gasket leak (look it up), so doing the plenum fix would also replace a leaking intake gasket in the process.

 

Got it. Hijacking my own thread, I towed the new hauler home today, about 50 miles through mountains. It towed pretty well, able to maintain 50 up a pretty good grade. But midway through, I heard noise from the tranny that didn't sound great. It shifted fine the whole way home, but at the first stop light, I could smell tranny fluid. When I got home and stopped, it was definitely dripping tranny fluid. Did this thing already kick the bucket? Checked the fluid level and it was fine, but I'm guessing no good comes from tranny fluid getting out. Thoughts?

 

I'll add that the fluid seemed to be coming out from somewhere near the radiator more on the drivers side. Is there a pressure relief valve of some sort? I fired it back up and shifted through the gears, although I didn't drive it and there is no fluid leaking now.