(Not your normal) Oil Pressure Question

I have had several issues since going through some mud near Little Moab last weekend. Some may be related, some may be irrelevant, but I need advice from someone with more experience. Here are the symptoms in order of appearance:

1 - Immediately after going through the mud puddle the enging idled at about 2000rpm. It went back to normal after being on the highway for a couple of miles.

2 - Engine temp guage started cutting out on the way home. It would show normal then quickly drop to zero, then jump back up. Probably just water in the sensor.

3 - Slight overheating on the way home (like many others who went through the mud). Got a little warmer than normal, but didn't get into the red.

4 - Oil pressure going whacko! It was normal all the way home Saturday. I got in to drive a few blocks on Sunday morning and the pressure went steadily up to 80, then suddenly dropped to zero. I didn't stop because I figured the sensor had water in it just like the temp guage. I soon found out that the reason it went to zero is that the filter split open along the seam. (Has anyone ever heard of an oil filter exploding before?) Pumped oil onto the street for three blocks til it was empty. I bought a new filter today and filled it up with oil. Guage stayed at zero for a few minutes, then began to climb to normal, then kept climbing right up to eighty again. After a few minutes at eighty it dropped to nearly zero (no gushing or dripping this time though). It still registers about 18-20 at 3000rpm, but nearly nothing at idle.

I'm not too concerned about the first three problems, but the fourth item has me worried. Anyone know what the problem could be, and how to fix it? I would sure appreciate any help, and I hope this doesn't mean a rebuild or new engine is necessary.

sounds like the pressuer relief deal on the pump went bad

Agree that the pressure relief valve in the oil pump may have got stuck open. You may also have sludge or other debris clogging the oil pump pick-up screen. You might be lucky and not have toasted rod/main/cam bearings but you won't be sure until you pull off the oil pan and inspect.
BTW, oil filters usually explode when there's too much oil pressure i.e. when the oil pressure relief valve is stuck closed. Yours must have stuck closed first and now it's stuck open.

Excellent. Thanks for the help. I'll pull the pan and check things out. I'll search to see if I can find a writeup of how to do that, but if anyone has a link handy I'd appreciate it.

The pressure control is in the filter housing no need to pull the pan.

I'm getting confused. I read some threads where people said the relief valve is in the oil pump. Isn't that right? Don't you have to take the pan off to get to the pump? If anyone had a picture of what it even looks like that would be a great help.

The oil pressure relief valve IS in the oil pump and you DO need to remove the pan to get at the pump.
The oil filter does have a bypass valve but that's only to allow oil to pass through if the filter becomes clogged.
Check out the oil pump thread in this forum. You'll find answers to more questions that you'll have.

Thank you Dyno. I'll tear into it today.