Hey fella's, finally got the 97 Ram 360 out and running since I started the rebuild back in November. All seems great, great power, etc, however my oil pressure is crazy.

Background: Block was hot tanked and bored out to 30 over, Crank and Cam journals were still like new, even at 197k. So installed new standard size Crank bearings, Rod Bearings, and Cam Bearings. Also installed a new Sealed Power Oil Pump, PN: 2244166. I only run MOPAR oil filters, PN 090. I also ran 10w30 on 1st break in, non-synthetic GTX. Have always run 10w30 GTX, never had oil pressure issues.

Well, I changed out the Oil pressure switch last week, nothing changed. Today, I bought some synthetic GTX 5w-30 and new MOPaR filter, filtered the used oil out w/ a paint strainer and found nothing, ie. metal shavings, etc. oil was clean.. I am still dealing w/ the low pressure.

Symptoms: upon start up, oil pressure is about 40psi on the gauge, stock gauge in the cluster. always stayed at or just below 40psi prior to rebuild. Also, have never run anything other that 10w30 in this truck since I bought it in 1999. Once engine warms up to temp, it drops about an 1/8" on the dial, just below 40psi mark, then just drops off completely, like the gauge is dead. engine is idling about 650RPM when warmed up, per my computer, as I slowly rev motor, at about 800-1000 rpms, the oil pressure goes back to what looks like normal, 40PSI, the middle of the gauge.

I plan on getting an oil pressure test set and hook it up to get some real readings, but am baffled as to why this is happening. You'd think w/ new bearings, I'd have closed the gap from the used bearings and actually increase oil pressure some, but this is not the case that I can see

thoughts??

thanks in advance..

 

I would suspect you still have a bad oil pressure sensor. Not like I have never gotten a bad part, right out of the box.

 

Is def. possible, but the old and new sensor, both do the same. pressure is fine, until the oil gets warmed up. will obviously need to hook up a manual pressure gauge this week.

 

Ok, hooked the ol' Harbor Freight Oil pressure test kit and once warmed up, she's at exactly 6psi w/ her in drive at idle and 8PSI in Park. 6PSI is minimal at normal idle, however what is normal idle, park or Drive? Also found that oil pressure switch activates oil light to come on between 5-7 PSI. so switch is definitely good. any other thoughts on this? NOt sure why w/ new bearings throughout motor, oil pressure would drop.. thoughts??

Additionally, it is idling right about 700RPM's +/- 10. verified w/ my diagnostic computer and matches the cluster also. Of course this drops to about 600-650 in drive at idle. Nothing running auxiliary, ie. AC, etc. At 1500-1700 RPM's it's at 40ish PSI, and at 2500 it hits 50 PSI. anything higher RPM, will not budge over 50 PSI, but within spec at higher RPM's.

What about seating the rings, engine still really not broke in yet, again had to bore it out to .030 over, so got new pistons and rings.. would this affect it?

 

Rings won't have any affect on oil pressure. Is it still the original pump? Or did you install a new one?

 

Hey, it's a new pump, PN in initial start of this thread. I installed a sealed power pump.

Break

I've worked on 2.2/2.5 Daytona/chargers/Omni's over the last 20 years. They have a restrictor plug on the block which helps increase oil pressure, wondering if the the 360 block also has an oil restrictor plug that I may not have installed which could be causing the low pressure?

 

Only one I can think of to check would be the one directly below the oil pressure sensor. I know on the 360 LA there was one back there and the easiest way to check was to put a rod down through and see how deep it goes. I believe the measurement was if you put the rod in the and sensor hole and it dropped down 7 1/2" the plug was there .

Also not saying you didn't take a bad sensor out, buy a bad sensor from factory, and are comparing bad to bad. Wouldn't be the first time electronics come bad.
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Thanks Alley, just found this in the FSM:
"Inspect the oil line plug, the oil line plug is located in the vertical passage at the rear of the block between the oil-to-filter and oil-from-filter passages (Fig. 17). Improper installation or missing plug could cause erratic, low, or no oil pressure. The oil plug must come out the bottom. Use flat dowel, down the oil pressure sending unit hole from the top, to remove oil plug.
(1) Remove oil pressure sending unit from back of block.
(2) Insert a 3.175 mm (1/8 in.) finish wire, or equivalent, into passage.
(3) Plug should be 190.0 to 195.2 mm (7-1/2 to 7-11/16 in.) from machined surface of block (Fig. 17).
If plug is too high, use a suitable flat dowel to position properly.
(4) If plug is too low, remove oil pan and No. 4 main bearing cap. Use suitable flat dowel to position properly. Coat outside diameter of plug with Mopar Stud and Bearing Mount Adhesive. Plug should be 54.0 to 57.7 mm (2-1/8 to 2-5/16 in.) from bottom of the block"

I definitely don't recall doing this during the rebuild. Hope if this is the problem, won't be too bad to install a plug!

 

Well, just pulled the pressure switch, ran a wire down the oil tube, and there is a plug at 7 1/2", so this is not the problem. I will take switch back to parts store and get another to see what happens. watched this vid today, and my symptoms are exact, so may just be what Hey You stated, a bad switch out of the box new.

 

If the mechanical gauge is also showing low pressure, the sensor isn't the problem. I believe the pressure relief valve for the pump is actually ON the pump. Wonder if it is sticking too far open?