Changed the oil today and saw this, pretty sure it wasn't leaking last oil change. It's not coming off the filter base, pressure sender looks dry. Ideas on the source? The rest of the pan and timing cover are dry, only the section shown by the starter and below the filter have oil on them.

 

Looks like its tome for O rings in the filter adapter housing.
The first pic shows the bolt to take the whole thing off.

Edit:
If I'm looking at the pics correct.

 

It does appear to come from the adapter housing, if that's what you call the 90 fitting (for lack of a better term). Either at the base where it mounts to the engine block or the nut? I'll look in my PCM manual for details.

Edit: no information on the housing in the PCM manual, anyone have this information? I don't want to remove it without knowing what I'm getting into. If it's just an O-ring, that's not a problem, don't want to mess anything up. I'm thinking there may be a pressure relief valve, spring?

 

That first pic you can see the bolt. the face of it has an O ring and there's one where it meets the block.
I believe they can be bought as a "kit"(3 rubber rings)
I also have an 89

 

For your oil filter adapter O rings, this is known to be a good choice> Renix kit from Crown Automotive-33002970K Don't bother with a "universal" kit from big box.

On top in the link in my sig. are links to Cruisers stuff, highly recommended reading. Below is some stuff I found. Cheers!
Here is some O ring info. It's for later HO engines, yours has a hex bolt>>
http://www.myjeepxj.com/cherokee-rep...filter-adapter

 

Just ordered the O-rings from Crown retailer on-line, $23 delivered to me. No local distributor.
Thank you very much.

 

Ouch! I thought it waz closer to $8.....Reported to be the right stuff though. ....At Wall mart is spray engine degreaser. There in the parking lot you can spray (not on the dizy or manifolds), then, to the car wash, engine running, you can put the high pressure to places.......(old cloths and eye protection).

Cleaning will make your job easier, just be cautious. It's enough pressure to blast crud past seals, "violate" electronics. Moderation is good....you can do a real # on allot there that way though, firewall, under hood, inner fenders.

If it dies, don't do that again.

 

I like the foaming cleaner, then use a wand that has an on/off ball valve that regulates flow along with a tip at a 45 degree angle. It's an RV accessory, for cleaning out hot water tanks. Works well to get in tight spots and not enough pressure to do harm.
That mess is limited to right side of pan, lower block below filter adaptor. Not to bad, considering.

 

At one point one of mine was so bad I left smoke gassing it up my hill to my place. The sustained extra throttle would make the oil soaked section of the exhaust where it crosses over, burn off. Might be lucky there that it never lit!