99 4.0 - Low Pressure and knock
I have read several threads about this issue, but have not found a similar situation yet...
I was wheelin' over the weekend and had a ball. Ran for about 3 hours in the AM. No issues and everything worked very well. It was warm outside, about 90 or so. Took the Jeep back to camp and had lunch for about an hour. After getting back from lunch, I started the Jeep and hear a ticking / knock sound. Opened the hood and it was coming from the fuel runners / exhaust manifold. So, I immediately thought I had a cracked manifold. The sound kept pace with the RPM's. So, I shut it off, looked under the hood for a minute, then started back up. It made the same noise for about 15 seconds, then went away. Has not made the sound sense. I did notice that while creeping on the trail, the oil pressure got low. At idle, it kept 15 - 20 psi, which is low to me, but OK.
What could this be? I have 145k miles on the motor, so should I go to something like 10w40 or 10w50? I use 5w30 right now.