First off, I want to express my gratitude to this forum. I’ve lurked for a while and finally broke down and made an account. This website helped me through my plenum job and countless other projects on my 2nd gen.

Ok, so backstory. I have a 98 Ram 1500 with the 5.9. My oil pressure was all over the place and I suspected the screen was clogged. I replaced the rear main seal, oil pump and pickup tube, and pan gasket. Truck fires up and drives as usual. Not leaking any ***new oil***

1. However, I am still getting odd pressure readings ie below 40psi at 60 mph and ~1.5-2k rpm. The needle just randomly drops, hangs out for a little bit, then recovers. Pressure switch was replaced 1 month ago. Normal for me is 40psi at idle and ~55-60 psi in operation. I assume it still falls within the acceptable range but is this normal?

2. After test driving for a while, I crawled under and noticed old oil near the bottom center of the inspection plate on the bell housing. I cannot pinpoint the origin. Note that this is old oil. I hypothesize this could be oil that entered the bell housing when I pulled the pan and now it’s leaking out through the notch in the inspection plate. Or, the rear main seal didn’t seat correctly, though I was very meticulous with this- seal is oriented correctly and offset on the block and cap so the seams aren’t aligned. Please see photos below. Just curious everyone’s thoughts.

I appreciate all of y’all!

 

Are you relying on the dash gauge? I wouldn't trust that for a second with your odd symptoms. Sounds like an electrical issue.

Install a mechanical gauge before you do anything more. I had one on my '90 Bronco and loved it -- instantaneous, accurate readings.

 

Hey Keith,

Thank you so much for responding- yes I am relying on the dash gauge. Mechanical makes more sense! I’ll give that a shot. Thanks again!

 

Even the cheap Sunpros or Autogage (or whatever they're called now) should be fine. No need to shell out for Autometer, although it may come with nicer nylon tubing -- not sure.

You can also try to just temporarily plumb it onto your cowl or thru the driver window-- anyplace you can see it while driving, and see if the symptoms truly exist while driving. If you can tee it at the block then it's REALLY fun to compare mechanical (almost surely accurate) to the dash gauge (who knows, maybe kinda-sorta).

 

The oil leak you see could be coming from the back of the valley and tracking down the back of the block.
Reach over the back of the block behind the intake manifold and feel if it’s wet.

 

The oil pressure sending unit at the rear of the block could also be leaking, too. It could cause an oil leak and the oil pressure fluctuations.

 

Back of the block is dry. I did the Hughes plenum fix back in June. What stumps me is the inspection plate is dry and the oil pan is dry. So leak appears to be coming from inside the bell housing through the raised notch bottom center on the inspection plate

 

Replaced that back in June when I did the intake and plenum gaskets and had no issues

 

Thank you so much for sending brands. I’ll be getting on this ASAP!

 

Did you loosen the caps(to lower the crank) or do it in place? You may want to remove the plate and get a better look at where it may be coming from.