Engine/Transmission (1994 - 1998) oil pressure

[Bob4x4]

The unreal oil pressure readings only come after a reflash on some year 24v's



Bob

 

[JGheen]

Originally posted by britannic

Just behind the steering pump on the driver's side (assuming left hand drive).

Thanks, and BTW how many right hand drive Dodges have you seen??

 

[britannic]

RH Drive Conversions



There's still a number of places that drive "on the wrong side" of the road :



Which Side of the Road?

 

[grtescpa]

Originally posted by zues

When I start my truck in the morning, the oil pressure takes about 6 seconds to move. The temp outside is only 50 degrees. After the truck warms up it still takes about 3 or 4 seconds to move on the needle. Should I worry about it or what should I do.

When you start your diesel, just listen to it. You can hear when the oil pressure comes up. Depending on how many days it sits still the oil pressure comes up in 10 to 25 secs. Confirm it with a mechanical gauge and don't worry about it.

 

[redram]

First - This is the 12 Valve Section of the forum

Second - Electronic Flashes do not work on my 12 Valve engine very well: Oo.



Third - the stock Dodge sending unit is located on the driver's side behind the power steering - vacuum pump and requires a special deep gauge sending unit socket to remove in most cases. This stock unit is known to fail and is a 45 dollar item from dodge.



Fourth - my gauges on my 96 do vary with operating rpm and operating temperature. (Except the fuel gauge - it's been reading empty for 4 years! (frikin' OE crud) However, the signal sent to the PCM may be damped or averaged to avoid huge swings in readings for the oil and water temp readings.



Fifth - Like Joe G stated you can get "mechanical" oil pressure readings from several places on the engine block, the most commonly used are teeing into the stock sending unit location (1/8 NPT) or on the top of the oil filter housing (1/8 npt).



Sixth - anybody that can 'blow up / burn down / melt down" multiple engines in a few years deserves everyone's attention as an ace mechanic on this forum.....



Seventh - the reason that the water temp gauges did not read high on your "melted blocks" was the sending unit is designed to read a liquid temperature, i. e. it is an immersion thermometer. When a cooling system leaks and coolant drains out yielding an empty engine block, the water temperature sensor no longer functions because it was not designed to measure "steam!"



Keep on truckin'

 

[wbrown02]

On top of the oil filter next to the oil line going to the turbo you should find a 1/8 pipe plug . Remove this plug and use it for your new gage... .

Listen to your motor as you start it... ... . with no oil pressure..... you will hear lots of things making noise that goes away within 30 to 40 seconds as your oil pressure builds... . the sound you hear is metal against metal... . pounding each other... experts say that this is when most of your engine wear takes place... ... Masterlube makes a pre oiler that works very well and is quite simple... ... A canister about the size of two oil filters stacked on top of each other... . with a check valve in the bottom and a electric switch under the check valve... ... fill the canister half full of oil... ... pressurize the canister with Schroeder valve in top to the highest oil pressure your motor achieves... ... there is a gage on the canister also (to you show you air pressure. )... remote switch in cab... ... . Starting is simple..... hold the switch open until you see oil pressure on cab gage... . then start motor... ... you will not hear the metal against metal ever again. Works for me! AS oil pressure builds it refills the canister to the original level and re pressurizers the canister at the same time for the next cold start... ... only time you mess with it is when you change your oil.

 

[Forrest Nearing]

Originally posted by Joe G.



My gauge does respond to oil pressure changes. If the engine is cold the oil pressure at idle shows the needle on the high side of the 40 PSI mark just touching the mark. After it is warm it idles with the needle about the width of the needle below the 40 PSI mark. At higher RPM it always reads a little bit more than the cold idle reading. That appears to be the pop off point for the relief valve in the oil pump.

I just discovered today that this isn't true...



my factory gauge does the same thing. I had been meaning to hook up a mechanical gauge for a while and finally got around to it today... cruising along at 1500-1800rpm w/ hot oil, I'm seeing 60psi easy... I've seen 80+ and I haven't even taken it up to 3000+ yet!



I guess my oil pump and bearings are in good shape after all! LOL!



Forrest

 

[Joe G.]

Either they have changed the oil pressure regulation system between when my '95 was built and when your '97 was built or something is wrong. According to my Dodge service manual on page 9-190 the oil pressure regulator valve opens to allow oil to drain back into the pan at 65 PSI. When my truck was new the warm idle was right on the 40 PSI mark on the gauge. It would move above that mark when running at road speeds. Now it idles when it is warm just below the 40 PSI mark. I would not expect to see a change like this if the gauge was lying to me. If you are seeing those numbers on a good gauge then something may be wrong.



The engine specifications page has a list of minimum oil pressures:



At idle speed 10 PSI

At 2500 RPM 30 PSI

Regulating valve opening pressure 65 PSI.



There is a foot note that reads: "CAUTION, If pressure is ZERO at curb idle, DO NOT run engine at 2500 rpm.



All of this stuff is in the section on how to overhaul this engine.

 

[Forrest Nearing]

I did a search, and it seems that a number of other guys w/ mechanical gauges report similar pressures...



do you have an aftermarket gauge on your truck?

 

[Joe G.]

I don't have a mechanical guage on it. However, I do have a 60 PSI mechanical fuel pressure gauge that I can make some tests with. This gauge agreed with the electronic Westach fuel pressure gauge that I replaced it with. So I think it is accurate enuff to use to test this. I'll give it a test sometime this week after I return from an unexpected trip. I will report the results on this thread.



I don't need gauges lying to me. If it is then I'm really puzzled at what the service manual says. I took this gauge off because in spite of damping the fuel pressure spikes it still vibrated some. Ugly too.

 

[Forrest Nearing]

I hear ya... like I said, I was shocked!!



did a search a little while ago and found that it might actually be fairly normal...



I'd be interested to hear your results.



have a safe trip!



Forrest

 

[britannic]

Originally posted by Joe G.





The engine specifications page has a list of minimum oil pressures:



At idle speed 10 PSI

At 2500 RPM 30 PSI

Regulating valve opening pressure 65 PSI.



There is a foot note that reads: "CAUTION, If pressure is ZERO at curb idle, DO NOT run engine at 2500 rpm.



All of this stuff is in the section on how to overhaul this engine.

I think that warning should be amended to read:





"CAUTION, If pressure is ZERO at curb idle, DO NOT run engine AT ALL!!".

 

[krs]

redram... ... ..... BRAVO!

 

[Joe G.]

Forrest,



I ran some tests today. I found that I have a gauge that goes up to 160 PSI that I had used for transmission work. I think it is pretty accurate. I installed it in place of my marine alarm sensor. That is in a T fitting with the stock sensor on the other leg. I used a long hose from the fitting to the gauge and routed it into the cab so I could watch both gauges at the same time. It's the same hose I used to road test my transmission when I overhauled it. It's pressure hose with 1/8 NPT fittings at both ends.



I noticed that the stock gauge has 40 PSI at the center and 110 PSI maximum. This is not exactly a precision gadget in the first place, especially in the upper portion of the gauge.



When I started it the reading was 60 PSI at idle and 80 PSI at 2000 RPM on the mechanical gauge. The stock gauge was about the width of the needle above 40 PSI for both readings.



I took it for a drive to get some readings at operating temp. After the engine was warm the idle reading was 32 PSI on the mechanical gauge and the needle on the stock gauge was below the 40 PSI mark a little. At 2000 RPM the mechanical gauge showed 62 PSI and the stock gauge showed the same as when it was cold.



It appears that the pressure reading from the stock gauge is clipped at about a needle width above 40 PSI and lower readings appear to correspond to the mechanical gauge. As I ran the engine up from idle to 2000 and back to idle the mechanical gauge moved in step with the stock one. The mechanical gauge maximum reading was at about 63 PSI or so regardless of RPM after the engine was warm. It only exceeded that measurement when the engine was cold. I was running with OD locked out on the transmission and the TCC was forced to be unlocked. That way when I lift the engine would drop to idle.



I managed to keep it between the fences and not hit anybody while I was testing.



At least on my '95 the stock gauge is not lying about pressures in the 0 to 65 PSI range. In fact, the only lie I detected was when it was cold and the engine was running at 2000 RPM. This may reflect the decreasing precision in the upper portion of the stock gauge.