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-   -   Hemi Oil Pressure Number Low or Normal (http://www.jeepgarage.org/f183/hemi-oil-pressure-number-low-or-normal-28828.html)

ChrisWk 09-21-2011 12:19 PM

Hemi Oil Pressure Number Low or Normal
 
I got a dashhawk installed in my jeep.I can read oil pressure I got a 05 5.7 Hemi The reading on the gauge at idle it goes down to 22psi and driving it goes up 48 to 50 psi but once I stop at lights, traffic it goes down to 20 to 22 psi. Is this normal ? My oil level is fine. I use mobil one 5w20 syth oil.

Thanks
Chris

kmitch80 09-21-2011 12:49 PM

Re: Hemi Oil Pressure Number Low or Normal
 
completely normal. If you live where its really hot, i would go with a little thicker oil, 5-40W. if its cold, then stick with the 5-20

01grand 09-21-2011 12:53 PM

Re: Hemi Oil Pressure Number Low or Normal
 
Dont know much about the Hemi, but on my 4.7L and my old 4.0 the oil pressure always fluctutates, especially once the vehicle is good and warmed up. The oil pump is driven by engine rpms, so at low rpm the pressure will go down, and when moving the pressure will go up. (assuming the oil pump is driven off the crank or cams on the hemi like my engine)

mrtosh 09-21-2011 01:15 PM

Re: Hemi Oil Pressure Number Low or Normal
 
Rule of thumb is at least 10psi per thousand revs at idle. Idk how accurate those dashhawks are for oil pressure readings anyways.

Drew 09-21-2011 03:50 PM

Agreed, I was always taught 10 per 1000 as well.


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Walt 09-21-2011 05:47 PM

Re: Hemi Oil Pressure Number Low or Normal
 
Quote:

Originally Posted by kmitch80 (Post 488005)
....i would go with a little thicker oil, 5-40W. ....

Your readings are similar to the values I see on the DashDAQ XL. The pressure relief valve limits the upper oil pressure value.

5W-20 oil or the MDS on your 5.7L HEMI will probably not function correctly. See the penultimate paragraph in the first section of this link: http://www.wkjeeps.com/wk_engines.htm#MDS

jeepgcoman 09-21-2011 07:04 PM

Re: Hemi Oil Pressure Number Low or Normal
 
Your pressures are almost identical to what both my Hemi's read on the DashHawks. The DH takes it's info. right from the PCM, so it should be as accurate as the sending unit providing the info. to the PCM. From the FSM:


3. Oil Pressure:


Curb Idle–25 kPa (4 psi) minimum


3000 rpm–170 - 758 kPa (25 - 110 psi)
4. If oil pressure is 0 at idle, shut off engine. Check for a clogged oil pick-up screen or a pressure relief valve stuck open.

For 5.7L engines, SAE
5W-20 engine oil is recommended for all operating
temperatures. Vehicles with 5.7L engines equipped
with Multiple Displacement System, (MDS), must
use SAE 5W-20 oil. Failure to do so may result in
improper operation of the Multiple Displacement
System (MDS).These engine oils improve low temperature
starting and vehicle fuel economy.



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