Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (
-   Trouble Shooting/Problems/Service (
-   -   pentastar V6 oil pressure question (

americanbulldog 02-26-2012 04:14 PM

pentastar V6 oil pressure question
I was wondering if anyone could tell me if this is a normal condition or not:

I've noticed that when the engine and the oil are cold, the EVIC says that the oil pressure is 80 psi (+/- 5 psi or so). That seems very high to me. As the engine warms up and the oil temperature reaches about 150 degrees, the pressure quickly drops and stays in the 30 psi range, dropping to as low as 27 psi. I've never had a gauge that told me the exact oil pressure before, so I was wondering if these pressure variations were ok or should I take it in for service before the oil pump goes out. The engine also uses oil, could this be why?

Parks311 03-01-2012 03:18 PM

Re: pentastar V6 oil pressure question
I'm not sure if it is "normal" or not but my V6 performs exactly the same way.

brandont 03-01-2012 04:27 PM

Re: pentastar V6 oil pressure question
Mine also - 80psi until warm. I do know that the OP is variable. Above a certain RPM (3k, I think) the OP will go up 65 or 70psi, I think. I would assume that since ours all do the same that it is normal. Probably cranking up the pressure during warm up to make sure oil gets where it needs to.

77Cherokee 03-01-2012 05:51 PM

Re: pentastar V6 oil pressure question
Cold engine oil is thicker. I believe that creates higher pressure. As the engine warms up the oil thins out and the pressure drops. At higher rpm's, the oil pump works faster, increasing the pressure. Every vehicle I've had with a pressure gauge worked the same way.

thall 03-01-2012 09:42 PM

Re: pentastar V6 oil pressure question
same situation here, cool or cold engine it will approach 85+ psi with rpm's... when fully warm is it rpm dependent...

idle ~26 psi
2k crusing... 40psi
turn it up and above 3500 it will again be 60-80 psi.

Would this not also have something to do with the variable valve timing, taking oil pressure to operate the mechanisms?

also read something on pentastar page about a high/low pressure solenoid??

Willir2 03-02-2012 10:49 AM

Re: pentastar V6 oil pressure question
Same numbers here. I took photos to show my shop at my next oil change, will see what they say. I'm sure they will look at me and laugh and say all normal.

americanbulldog 03-02-2012 02:30 PM

Re: pentastar V6 oil pressure question
Thanks everyone for your responses, I'd have to say it must be normal because we're all seeing the same thing. It's nice to have this forum to figure these things out, saves alot of time and $$$.

mr_bots 03-02-2012 05:56 PM

Re: pentastar V6 oil pressure question
It's normal. The Pentastar has a variable displacement oil pump. When the oil is cool and the engine RPM is above 3500 it runs in high pressure mode, when the oil is warm and the engine is running below 3500rpm its in low pressure mode.

mistadobalina 03-02-2012 09:40 PM

Re: pentastar V6 oil pressure question
I checked mine too so I will chime in. Was at 87 at start up. Stays at 37 cruising around 1900-2000 RPM (2012 V6)

thall 03-02-2012 10:20 PM

Re: pentastar V6 oil pressure question
info from a source... but i am still looking for 'how' the variable cam timing devices work.. via oil pressure or what...

Oil system and engine lubrication

The advanced oil filter system eliminates oil spills, thanks to an incinerable filter element instead of the typical spin-on filters; the filter is conveniently located on top of the engine.
A chain-driven, vane-type variable displacement oil pump adjusts the flow rate and pressure as commanded by the engine management system, which uses a solenoid to drive the pump into low or high pressure mode. For example, below 3,500 rpm, the pump conserves energy by using low pressure; at speeds over 3,500 rpm, the pump switches to high pressure.
A force balance mechanism inside the oil pump adjusts the size of the pumping chambers to alter oil flow. If the oil is cold, the pump reduces the size of the internal chambers. When the oil is hot and thinner, more oil is needed, and a spring increases the size of the pump chambers. This also saves energy.
The pump is driven at a 1:1 drive ratio; its location under the block is more efficient than an on-crankshaft location. An internal, mechanical ball-and-spring relief valve dumps oil into the sump when needed, for conditions such as a cold start with high engine speed. Both pump and pressure regulation solenoid are non-serviceable.
The engine takes six quarts of oil with a filter change. Traditional, non-synthetic motor oil with an ILSAC standard of GF5 is recommended. The standard change interval, with this oil, is 8,000 miles under normal driving conditions.
The oil pick-up tube is supported at the windage tray. Three oil gallery plugs are in the engine block; oil pressure an be monitored with a scan tool. Oil pressure and temperature sensors are on the oil filter housing assembly, which is mounted on top, between the heads; the oil cooler (a plate-style coolant to oil heat exchanger) is mounted to the oil filter housing as well. With Wrangler, specific upper and lower oil pan requirements have been engineered into the engine to provide increased grade requirements, keeping the oil within reach of the pump when the vehicle operates at steep angles (Wrangler also has a higher-mounted alternator to allow for water crossing, and a unique intake system with induction handled by a revised throttle body on the left side, where other Pentastars keep the intake on the right).

padgett 03-03-2012 03:24 PM

Re: pentastar V6 oil pressure question
Just a minor point: HIGH pressure is at OIL temp under 158F OR rpm over 3500 rpm.

Also the spec seems to be anything over 5 (five) psi at hot idle is ok. Warmed up mine runs 25-30 psi at idle and high 30's at 70 mph cruise.

All times are GMT -5. The time now is 07:45 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community