I had this issue once before with oil pressure dropping to zero but obviously motor sounds fine. I replaced the sensor last time and it was fine till today when I noticed the check gauges light came on again. This seems to only happen when at a stop. It came right back up as soon as I started to move. They are bad to replace but can be a pain. I can't remember when I changed it but maybe 6 months max. I just can't see if or why it would start to act up? Truck been running great and I did have to add a quart of oil. It has 163,000 miles on it and I did the upgrade with the new thick aluminum plate. I haven't look down the throttle body lately but the last time I looked it was clean. What do you guys think?

 

Oil pressure is always lowest at hot idle so the fact that it only does it when stopped isn't encouraging.

Would sure be nice to have a real gauge on it.

I don't know when these Magnums start to knock or tick but Ford small blocks are quiet at literally a couple pounds of pressure. So, you could have just a few psi and this may not be enough to please the gauge but is enough to prevent any noise.

An easy experiment could be to drain the oil and fill with 20W-50 or even HDEO 15W-40. If the problem vanishes, your problem actually is low oil pressure

 

It was just weird since it didn't do this when going into work but when I was backing into my drive way is when it happen. It was maybe a couple of seconds. I was planning on doing a oil change this weekend since I didn't write down the millage but I know I am below 3,000 easy. Being where it's located would make it a task if maybe look into a tree type part where I could keep the sensor working but have a line for maybe a manual gauge that I could either mount maybe under the hood to be able to check to see where the pressure is? I could do a heavier oil like you said for now but not sure about the HDEO. I looked it up not knowing and it talks diesel. I need to figure this out.

 

Check gauges lite and oil pressure gauge are two different things. If the oil pressure is low it will show on the gauge and the light will come on. What year truck is it?

 

HDEO is actually great oil and can be run in many gas engines with no problems. Typically has increased sulfur and nickel for increased lubricity and anti-wear properties (in theory), but beyond that the chemistry exceeds my pay grade.

That said, dumping in a heavier oil won't help unless the problem is fairly consistent. If it only happened once in your driveway... well, you need more repeatable results (or symptoms).

A real op gauge would be a fool-proof troubleshooting method. If you can work out a tee I'd just install permanently, maybe in an A-pillar pod.

You absolutely CAN run a true mechanical gauge into the cab, I did it on my '90 Bronco. You just have to get that plastic tube thru the firewall. OR you can run an electric gauge which is easier but theoretically less accurate and slower to respond. I like the raw, no-nonsense, immediate response of mechanical gauges but they are more challenging to get into the cab.

 

I know they make isolators for fuel pressure gauges, so, you aren't plumbing fuel line into the cab.... wonder if you could do the same thing with the oil pressure line?

 

Well it never dropped once today or before then but it has done that before. It was 93 degrees so its hot here in Florida. I changed out the oil pump around 10 years ago. The motor is quiet with no ticking so something off. Battery is new and cables are clean. I dont rough house the truck and I mostly drive it back and forth to work with maybe a store run here and there. I don't remember what I bought the sensor but if I was to guess. I most likely bought it of Amazon. I will just keep a eye on it. Also it's a 1999 for the person who asked.

 

If the pressure drops to zero at a stop, but, jumps back up to where it should if you give it even a LITTLE BIT of gas, the sensor is bad. 10 years out of one isn't too bad. Though, I remember when the manufacturers could make an OPS that would last longer than the engine.......

 

That's very possible. I did buy it from Amazon ( Sensor) June 11, 2022. That would make it only 3 months. I'm going to do a oil change this weekend so I can get the correct millage for the next change since I didn't write down the millage last time.If the drop happens again, I will just go to Napa and get a new one.
I would like to look into maybe a mechanical gauge. I just have to find out where to put it? I just shelled out a lot of cash for the main dash and I'm not real sure on the post type since this truck is pretty much stock and it would look out of place.