[jeepgrady]

Now that I've had my computer flashed I can see my oil pressure. Mine is running like 19psi. I see where someone posted pictures of his easter egg readouts and his reads 25psi. My other vehicles average between 40-60psi. What gives?

Please let's see what others are reading.Thank you.

 

[mileshoover]

Now that I've had my computer flashed I can see my oil pressure. Mine is running like 19psi. I see where someone posted pictures of his easter egg readouts and his reads 25psi. My other vehicles average between 40-60psi. What gives?

Please let's see what others are reading.Thank you.

According to the LX Service Manual, the 5.7 Hemi engine's oil pressure should be as follows (read as two columns):


"SPECIFICATION..................... SPECIFICATION
At curb idle speed (min)* ...........25 kPa (4psi)
@ 3000 rpm....................... 170 - 758 kPa (35 to 110 psi)

*CAUTION: If pressure is zero at curb idle, DO NOT run engine."##

##My comment --This is sort of a stupid note; hopefully anyone getting a zero reading will not be dumb enough to run the engine any longer than needed to get that zero oil pressure reading, but then again...!! :*))))

So, you can see quite a variance in pressures; these two are the only ones given in the manual. There may be others elsewhere.

Mine shows all of the above; yours should also.

 

[jeepgrady]

Miles,
What does the kPa stand for in your message?

 

[CottyGee]

The kPa is the metric measurement of pressure.

4 PSI is ridiculous. I can't believe they've even got the stones to put that in writing! That has GOT to be some lawyer talking at 4 PSI, because there's just no way that's optimal...

Running down the road, I'm at ~50 PSI. At idle, I think it's in the 20's IIRC.

 

[mileshoover]

Jeepgrady, not certain but believe it to mean "kilo Pascal" or engineering speak for a method of measuring hydraulic pressure.

If you want more, go to Google and search on it; there is considerable but the URL is too long to retain its full scope in this reply (I tried to add it here for you and lost most of the detail).

Does that answer your question? ;^))

Perhaps one of the engineering members would be good enough to enlighten us all more on this subject. I always though Pascal mostly worked on computer stuff.

 

[th59718]

You guys got it right. kPa is just the metric way of expressing the oil pump discharge pressure (psi in English units with an appropriate conversion factor).

I've got to agree with CottyGee. 4psi at idle sounds ridiculously low.

On a recent post by BrilliantBlackHemi (link below) showing EVIC v3.60 screens of readings in diagnostic mode, all readings seem to be in English units. However, IIRC units of measurement are selectable in the EVIC. The photos show an oil pressure of 24p (whatever p is, pounds or psi maybe??) at engine idle (622rpm). This sounds more reasonable, but definitely not the numbers Miles quotes from the service manual. So, now I'm really confused!

http://www.300cforums.com/showthread.php?t=1969&page=6&pp=9

I've never tried entering diagnostic mode. I just had mine in for oil change at 6000mi and Service Manager said there were five(!!) flashes they had to do to update computers. I never knew there were that many flashes out there. Maybe they were just trying to impress! Outside temp gauge works better now, though. I think I'll try that diagnostic mode to see exactly what I have now.

Update: Tried out the EVIC diagnostics mode. Oil pressure @ ~620rpm idle 27psi; 3000rpm - 59psi. My EVIC is v3.61 dated 7/27/04. It has a screen specifically showing the oil pressure as "27 psi" at idle.

 

[II kings 9:20]

4psi at idle is about as good as no psi, mine is 20-24 at idle and 50 or so cruising along, I had no idea until I got flashed to the 3.61.

 

[mileshoover]

.... The photos show an oil pressure of 24p (whatever p is, pounds or psi maybe??) at engine idle (622rpm). This sounds more reasonable, but definitely not the numbers Miles quotes from the service manual. So, now I'm really confused!...

Remember, the items I quoted earlier are apparently just an illustrated range for two conditions of RPM, so with that in mind, it sounds reasonable for the 3000 RPM data. I, too, wonder about the very low idle figure given.

FWIW, this wouldn't be the first time that the Service Manual has been found to be incorrect.

For example, we've already determined that the manual states the LX horns can be blown whether the ignition is on or not. When queried, DC states vehemently that this is incorrect; it is intended for the horn to be able to be blown ONLY when the ignition is turned ON. So...

 

[th59718]

I, too, wonder about the very low idle figure given.

I know this thread is probably dying but I do have one last thought to share.

The numbers out of the Service Manual are "specifications" and the 4psi is specifically called out as a "(min)". Some bright engineer at DC has figured out that at 4psi there will still be enough oil flow to the engine to prevent serious damage. 4psi is equivalent to approximately 9 feet of pumping head. This means that with 9 feet of available pumping head you should have at least some flow to the top of the engine which is, at most, 2 or 3 feet higher than the oil in the oil pan. When oil starts flowing you get additional pumping head from line friction, etc. When you get 6 or 7 feet of this additional head, there should be enough (ie., "min") flow - according to the specification.

My guess is the oil pump, in good condition at maximum rpms, puts out something like 120-160 psi (pretty typical of an inexpensive single stage centrifugal pump). A lot of this pressure is lost pumping thru the oil filter bringing you down to the nominal 35-110 psi for delivery to the engine at 3000 rpm, a "typical" operating condition. There's a big range here because a lot may depend on the condition of the oil and oil filter. The 3000 rpm specification sets both a minimum and a maximum. If you've got more than 110 psi, it probably means there's a line plug on the downstream side of the filter - a potentially disasterous situation. If you've got less than 35 psi it could mean a lot of things: your pump could be wearing out or broken, your filter might need replacement, your oil could be the wrong weight, your oil could be non-existent. At idle speed, the pump will generate less pressure (but way more than the 4 psi "min") and less flow (but way more than what you get at 4 psi "min").

Hopefully (I'd almost stake my life on it -- well, maybe not ) the oil pressure sensor is located at a point in the oil line after the oil filter. Otherwise, if the filter were to become seriuosly clogged, you could be showing plenty of pressure when in fact there was little or no available pressure (and consequently, no oil flow) on the downstreem side of the filter.

 

[developerx]

It's actually worse than it states...

kPa * .145 = PSI

25 * .145 = 3.625 PSI (obviously incorrect)

In reality, if your oil pressure is that low... your pump or regulator is gone and your lifters are sounding like jackhammers. If you hear the "clack clack" shut the motor off.

If it's hot and the oil is thin, I guess you might possibly see somewhere around 15psi in a decent motor (depends on idle too). Much lower than that... I'd suspect something is worn (bearings) or the oil is either broken down or the wrong viscosity.

I tend to think normal would be somewhere around 17-20 at idle & warmed up.

A spec error like that is forgivable. Of course, if it was that kind of mistake on a torque value... it could spell disaster.

 

[BrilliantBlackHemi]

Yeah I'm running 18-19 psi at idle after driving a little while. I run around 51psi on the highway at 60-65.

 

[developerx]

The 51 is the key. That's actually very good pressure for an engine that's at operating temp with a stock pump.