New from NC w/oil pressure question/ixsue

[JeffIsOld]

Hello folks!

 

My '95 2500 shows ~42 psi (factory guage) at start up in warm weather.

Drops to abt 35 at warm idle.

Stays abt 40 at hwy speed.

Just changed oil with 15/40 Rotella and 1 qt Lucas Oil Stabilizer with Mopar filter.I

 

My brother's 96 shows about 70 at idle and I am wondering if mine should be higher, or just an indicator issue.

 

Found out my pressure switch/sender is on L side. I thought it was behind the oil filter. (Stupid eh)

 

Obviously a mechanical guage would eliminate pressure questionability. Probably add one soon!

 

But what should it be?

[dripley]

A mechanical would be the way test it for sure.

 

And welcome. How is Richard doing?

[Mopar1973Man]

2 minutes ago, dripley said:

A mechanical would be the way test it for sure.

 

Don't trust the dash gauge is not accurate. Mechanical gauge will prove this quickly. 

[dripley]

Richard probably has a spare one.

[JeffIsOld]

Thank you folks.

 

I will wrestle up some fittings and get a mechanical gauge hooked up for safety.

 

Richard's getting old. Lost a few steps since his wife passed especially! 

[Guest 04Mach1]

32 minutes ago, JeffIsOld said:

Hello folks!

 

My '95 2500 shows ~42 psi (factory guage) at start up in warm weather.

Drops to abt 35 at warm idle.

Stays abt 40 at hwy speed.

Just changed oil with 15/40 Rotella and 1 qt Lucas Oil Stabilizer with Mopar filter.I

 

My brother's 96 shows about 70 at idle and I am wondering if mine should be higher, or just an indicator issue.

 

Found out my pressure switch/sender is on L side. I thought it was behind the oil filter. (Stupid eh)

 

Obviously a mechanical guage would eliminate pressure questionability. Probably add one soon!

 

But what should it be?

 

The oem dash oil pressure gauge in pretty much every light duty automobile is just there to give the driver a nice warm fuzzy feeling that the engine has good oil pressure. On a Dodge there are only 3 factory gauges I would trust and they are fuel level, tach, and speedometer.

 

A quality aftermarket gauge will give more realistic pressures. On a stock 6BT I would expect to see 40-50 psi oil pressure at idle operating temperature if I was diagnosing oil pressure issues. 70 psi at operating temperature is definitely higher than I've ever seen on any B Series Cummins.

[JeffIsOld]

2 minutes ago, 04Mach1 said:

quality aftermarket gauge will give more realistic pressures. On a stock 6BT I would expect to see 40-50 psi oil pressure at idle operating temperature if I was diagnosing oil pressure issues. 70 psi at operating temperature is definitely higher than I've ever seen on any B Series Cummins.

 

I am willing to bet he may also have an indicator also!

 

Thank you for the response!

[AH64ID]

14 hours ago, JeffIsOld said:

Hello folks!

 

My '95 2500 shows ~42 psi (factory guage) at start up in warm weather.

Drops to abt 35 at warm idle.

Stays abt 40 at hwy speed.

Just changed oil with 15/40 Rotella and 1 qt Lucas Oil Stabilizer with Mopar filter.I

 

My brother's 96 shows about 70 at idle and I am wondering if mine should be higher, or just an indicator issue.

 

Found out my pressure switch/sender is on L side. I thought it was behind the oil filter. (Stupid eh)

 

Obviously a mechanical guage would eliminate pressure questionability. Probably add one soon!

 

But what should it be?

 

 

I would compare warm engine pressures. 42 seems low for initial startup and high for warm idle. 70 at idle could be normal with oil temps below 50°F, but way too high for warm idle. 

 

In 95/96 the gauge was still a real gauge, so it's likely far more accurate than anything newer. 

 

 

[ofelas]

On the 6BT I'm driving today, cold idle pegs 80psi gauge with 5w30, 15w40, 0w40. 

 

It's 30F this morning.

 

Hot idle at 800 rpm in D at 32F ambient, I'm at 30psi with 0w40, coolant temp 193F.

 

In summer, 90F ambient, with 5w30, still pegs the gauge at cold startup idle, and is at about 25psi hot idle in D.

 

FWIW Cummins specs the 6BT to have a minimum of 10psi at hot idle with 15w40.

[Mopar1973Man]

5 hours ago, ofelas said:

FWIW Cummins specs the 6BT to have a minimum of 10psi at hot idle with 15w40.

 

10 PSI minimum oil pressure at 800 RPM idle.

30 PSI minimum oil pressure at 2,000 RPM.

 

 

[ofelas]

So we can conclude that JefflsOld's observed oil pressure is absolutely nothing to worry about, as long as those readings are verified on a known good mechanical gauge.

 

Worth noting - as long as the minimum HOT idle oil pressure is observed, its flow across the bearings, rather than pressure, that works best for engine longevity.

 

Kinda like boost vs airflow, but that's a whole different topic, along with the co relation between head gaskets, timing & EGTs 

 

An easy way to verify for domestic engines, whether gasser or diesel, is to pop the oil filler cap for those fortunate enough to have a fillable valve cover - if mild splash is observed at the top of the valve train at hot idle, you're good to go.