Yesterday I noticed a few drops of something on the pavement under the engine towards the rear. After driving home I also noticed a fuel smell once I shut the truck down and got out. 

 This morning I went out with a flashlight to inspect and didn't really see any wet spots other than on the rear of the cylinder head on the passenger side. It's a little damp there. I'm thinking maybe the banjo bolt for the return line? Looks like it might be difficult to get to, anyone know the size off hand? Do I need to remove it and replace the sealing washers or do these commonly vibrate loose from time to time?

 Also, while inspecting I saw the the center section of the front diff seems to be damp with oil or something. While looking down the front of the engine the crankcase vent bottle is pretty oily as well. Do these overflow if not emptied? I have not touched it since I bought the truck (forgot about it when I did the oil change).

The sealing washers are most likely shot. When changed mine i didnt think there was any rubber on them until figured out the rubber was almost as hard the steel part. It will cause the fuel drain back to the tank eventually and cause a hard start issue.

The vent bottle will puke oil and the fan will blow all over the radiator and plug it up. Best to remove it and reroute. @Mopar1973Man has good article on doing it in the articles section.

 I've read his article, just haven't got it done yet. I will see if I can attend to that soon.

 Where would the best place be to get the sealing washers for the banjo both if that is what's leaking?

DAP, Vulcan performance to name a couple.

Sooo, looked around on DAP and didn't find what I was looking for. Are the sealing washers 8mm, 12mm or 14mm? I've seen all three sizes. I haven't looked at things yet but if in fact that's what's leaking I want to be sure to get the right parts.

 I did see a new banjo bolt with seals on another parts site. I suppose I could just replace the bolt as well.

Pretty sure its 12mm. Just measure the old washer. 

 

https://www.dieselautopower.com/vulcan-bonded-sealing-washers-12mm

 Ok thanks. I suppose a quick call to DAP and they could probably tell me what size I may need.

 Going to try to get out today and check thing out a bit. It's a little cold out today and still dealing with my knee issue.

Geno's has them too.  They are indeed 12mm.

 

https://www.genosgarage.com/product/bf-3963983/gauge-related

 

 The banjo doesn't seem to be leaking, it has an oil film on it but I don't think that's the source of the leak. 

 Possible valve cover gasket? I have a video but it won't upload, to big. I'll try to screen shot a couple of views from the video and post them.

Pass side rear, you can see the exhaust manifold in the pic for reference.

If its fuel that banjo is about the only culprit. If fuel is leaking from the valave cover you have bigger problems.

Just to add though, do you see any leaks where.the injectors connect to the head? That will run off the back of the block, drivers side. Also there is a tee down below the banjo and back behind the fuel fiter canister. Drivers side again. That is the first place mine decided to leak fuel.

 At this point I don't think it's leaking from the return. I'm going to get under the truck tomorrow and inspect closer. I did look at the T you referred to, it's dry as well.

 I noticed the oil around the exhaust manifold of cylinder #6, that's what I was referring to a possible valve cover. I cleaned the areas with carb cleaner and will inspect those again tomorrow to see if I can tell what's up. It's not a bad leak by any means. Just wondering where it's coming from.

I started having a similar issue. I noticed a puddle under my truck one morning and noticed I smelled fuel, it hard started as well so I knew it was a leak somewhere. I felt the return line at the back of the head and it seemed dry, but I’m sure that’s where it’s leaking because when I park nose down in my driveway it starts up fine even after sitting 12+ hours, yet if I park flat or nose up it always takes 5-6 seconds of cranking before it starts.

Edited December 9, 20204 yr by ColoradoColt

 So far mine is starting normally on level ground.

Update****

 I located the leak. It's the fuel filter drain valve. It drips about every 5-10 seconds while idling. Gonna order one up here in a bit.

 While tracking down this leak I also found a bolt loose at the top of the oil filter adapter (if that's the correct term for it) where it bolts to the block, very top left bolt. Put a wrench to it and got nearly a full turn. 

6 minutes ago, Doubletrouble said:

Put a wrench to it and got nearly a full turn. 

I had a small drip from bell housing and checked my oil pan bolts, yep sure enough all lose, no more drip now

 Maybe I'll have to check those as well just to be sure. 

 Sometimes I'm afraid to be a little to heavy handed and over tighten bolts and squeeze the gasket out. Just have to be mindful and snug them up a bit.

7 hours ago, Doubletrouble said:

 Maybe I'll have to check those as well just to be sure. 

 Sometimes I'm afraid to be a little to heavy handed and over tighten bolts and squeeze the gasket out. Just have to be mindful and snug them up a bit.

I used a torque wrench on mine

 Last update**

 So you finally received the fuel drain valve thanks to the stupid slow snail mail. Installed it 2 day ago and so far no more leak. Simple install, best done with a magnetic torx driver.

I pull the fuel drain off of my landlord truck. (Other Shop). I used a T15 and just pull it off and change the 2 o-rings in the valve. Re-assembled and installed again just cost me about 10 minutes and 2 o-rings from my A/C stuff. 

 Had I known the size of the o-rings or had a good selection of them here I would have done the same. That being the case I just swapped out the whole thing.