07 JK - Oil pressure problems persist - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 7 Old 04-19-2017, 02:03 PM Thread Starter
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07 JK - Oil pressure problems persist

2007 JK Unlimited, 3.8L,

Oil Pressure light has been coming on intermittently. I've checked the obvious items of correct oil amount, viscosity, and oil filter replacement. I also replaced the Oil Sending Unit, and inspected the wiring. No codes are stored.

Oil pressure light still comes up intermittently, so I had the dealer tape an Oil pressure gauge to the windshield and drive it.

Oil PSI at idle was 15
Oil pSI driving was 35-70 psi

The engine appears to have the correct pressure, as The low pressure switch activates when oil Psi drops below 4psi. I took it back from the dealer who offered no explanation, other than the usual "wiring gremlin".

I've been driving it for a weak or so with intermittent OIL dash light, and non-stop dinger indication. Im seriously close to removing the audio dinger since I have no verified that the correct oil pressure exists.

Ground wires to the PCM seem ok. I did however note that the yell/purple wire from the Oil sending unit does not light up when i put a test light to it. I'm not sure if there is supposed to blower to the wire.

Any help would be greatly appreciated.

07 JKU Sahara
2.5" Rough Country BB
Pro Comp Dual Stabilizer
33" MT
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post #2 of 7 Old 04-19-2017, 03:52 PM
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oil pump?


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post #3 of 7 Old 04-19-2017, 04:01 PM
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Quote:
Originally Posted by JKunlimited07 View Post
2007 JK Unlimited, 3.8L,

Oil Pressure light has been coming on intermittently. I've checked the obvious items of correct oil amount, viscosity, and oil filter replacement. I also replaced the Oil Sending Unit, and inspected the wiring. No codes are stored.

Oil pressure light still comes up intermittently, so I had the dealer tape an Oil pressure gauge to the windshield and drive it.

Oil PSI at idle was 15
Oil pSI driving was 35-70 psi

The engine appears to have the correct pressure, as The low pressure switch activates when oil Psi drops below 4psi. I took it back from the dealer who offered no explanation, other than the usual "wiring gremlin".

I've been driving it for a weak or so with intermittent OIL dash light, and non-stop dinger indication. Im seriously close to removing the audio dinger since I have no verified that the correct oil pressure exists.

Ground wires to the PCM seem ok. I did however note that the yell/purple wire from the Oil sending unit does not light up when i put a test light to it. I'm not sure if there is supposed to blower to the wire.

Any help would be greatly appreciated.
If the wire going to the sensor grounds it will cause the light and dinger to go off. You can tap into that wire with a graphing DVOM to determine if the circuit is being pulled down or there is another issue. I have seen many occations where the OP signal wire shorts to ground for various reasons.

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post #4 of 7 Old 04-19-2017, 08:01 PM Thread Starter
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Thanks guys. UPDATE: As of today there is a faint whine from the timing cover/camshaft area. The whine is dormant at idle, and increases as engine RPM increases.

Since the oil pump is behind the timing cover area, that is the next logical step. It's a bigger job that meets the eye, as chrysler 3.8 oil pump installation videos don't exist, and priming of the pump sounds problematic.

07 JKU Sahara
2.5" Rough Country BB
Pro Comp Dual Stabilizer
33" MT
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post #5 of 7 Old 04-24-2017, 07:40 AM
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Hate to suggest this, but low oil pressure is often caused by excessive main and/or rod bearing clearances. 3.8s are sloppy to begin with. Has this engine ever been run low on oil?

'09 JKRU. 4" Teraflex long arm, Teraflex R44 housing, Teraflex / Fox Resis, Poly skids, Nemesis Billy Rockers, Nemesis flares, 37" ATZ P3s on 17" 5x5.5" Trailready HDs, Spyntec hubs, Yukon Hardcore lockout hubs, Teraflex BBK, Mopar BBK master/booster, Superior front & G2 rear axle shafts, CTMs, Reids, Synergy drag link & tie rod, 5.38s, TF Dual Rate front bar, TF bumpers, Warn Powerplant, Tom Woods shafts, AA xfer case cable, Kilby canister relo, RH4x4 cage.
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post #6 of 7 Old 04-24-2017, 08:38 AM
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Quote:
Originally Posted by SoK66 View Post
Hate to suggest this, but low oil pressure is often caused by excessive main and/or rod bearing clearances. 3.8s are sloppy to begin with. Has this engine ever been run low on oil?
0.0005" - 0.0022" mains and 0.0007" - 0.0026" rods is considered sloppy?

The 3.6L engine is about the same.

2008 Unlimited Rubicon Automatic

Last edited by ronjenx; 04-24-2017 at 08:48 AM.
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post #7 of 7 Old 04-27-2017, 03:27 PM Thread Starter
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I just pulled off the oil pan, and checked the rod bearings. There is side-to-side play(which may be normal), but Zero up and down play. I pulled one of the bearing caps and the bearing and crank journal look great.

07 JKU Sahara
2.5" Rough Country BB
Pro Comp Dual Stabilizer
33" MT
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