Oil Pressure

[cherokee401]

Got a 190E 2.3. I drove 100 miles the other day, pulled into my driveway, and noticed my oil pressure at zero. Slight rattling of the head hardware started. Couldn't have been on zero for more than 50 feet. Plenty of oil on board, no puddles. Restarted a couple of times, no oil pressure. I'm looking for somebody who knows these engines and possible problem that's new to me. I have a mechanical background, but I don't know what this is all about.

My uneducated theories are: pressure relief valve spring failed; the oil pump drive collar sheered; or the cam chain tensioner maybe failed, I don't know if that would dump all the pressure or not. It acts like it spit out a galley plug somewhere..l. all of a sudden, bingo, no oil pressure.

My engine is high mileage, but runs perfect. I know that engines don't wear out in two clicks of the clock. Does this sound familiar to anybody, and can you enlighten me about this?

I thought I would reach out for somebody else's experience, first, before I stupidly started doing exploratory surgery.

Thanks much,

Robin