No Oil Pressure
 

I have an 01 with a 4.0. When cold, pressure sits at 40psi, but after everything heats up, I have no pressure at idle and the check gauges light pops up. I bought it with 147k eight months ago, and it always ran over 40psi at speed. The issue started yesterday and after a few google searches, the two issues that have came up are the sending unit and a cracked head. I've read that the sending unit is a cheap fix but the cracked head sounds expensive. Is there anyway I can figure out the issue myself? I've never used any type of forum but any advice would be very appreciated.

Well, does the truck run right? Does it sound louder then be for? Is there a loud clanking or ticking coming from the engine? If not it is a safe bet that you have a bad sending unit. I have a 98 with 178,XXX on it, the pressure is above 40 while going down the road but at idle when warm then psi drops to 10ish. I worried a little, listened to the engine cause you will know when an engine is running at 10psi of oil pressure a LOT of ticking from the head will come. Like I said, no noise is good noise. Suggestion of a replacement sending unit is approved. If you want to really go into it you will need to tap into the oil system with a gauge to see what oil pressure you are at, wouldn't suggest it if you aren't hearing a loud tick.

Change the sensor... If that don't fix it you know the expensive fix is next.

What brand of oil filter you got on there?

Verify with mechanical gauge first. If it is low and not making noise and if you see oil flowing when you look through the oil fill cap you are OK.
After verifying and changing filter you have only 2 options.....rebuild or drive it. FYI mine has had the same symptoms for a long time and I drive it all over the state. You can change your thermostat to a 180 and that will raise your pressure a little and might keep the check gauges chime from bugging you. I have gotten used to the chime and don't even notice it anymore. As long as oil is getting to the rockers rest assured that it is getting everywhere else.

Thanks for all of the replies. Noticed coolant leaking onto trim underneath the radiator on the drivers side today. Hopefully that explains the continuous loss of coolant and the sending unit will take care of oil pressure. Taking to mechanic tomorrow to have coolant system checked out. Is the sending unit something I can pick up at local parts store, and if so is it an easy DIY install?

Makes me not feel so guilty about having to drive it to work for the last two days.

Sending unit is very easy install. About $25 from any parts store. All you need to is disconnect the electrical plug (slide the red switch) and use an adjustable wrench to unscrew ten minutes tops. It's located next to the oil filter.