Oil pressure light at idle

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

I hope that I didn't miss this addressed in a different section, but after an oil change using M1 0w40 I've developed an oil pressure light only present at idle in my '05 CRD with 82k miles. I've read in other posts that the sensor is fairly worthless, but does that mean that I don't have a larger issue brewing? It seemed to occur the first time while driving around a corner, but now is present every time the engine goes down to an idle. I changed the oil myself and didn't notice anything strange or amiss and have always kept it on a regular maintenance schedule.

I should not drive it until I get this figured out, right?

geordi · **Posted:** Sun Aug 25, 2013 1:09 am

The sensor is bad. Plain and simple.

That sensor is located in the WORST possible location, the ONLY way that sensor would ever trigger the light other than a sensor failure... Is when the engine itself has already locked up from losing ALL the oil.

Even when my turbo blew and pumped 1 GALLON of oil into the exhaust... That light never came on.

Change the sensor, it is the sole source of your problem. It is a cheap Chinese part, you may need to replace it 2 or 3 times to get a good one... Hopefully not though.

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

That was kind of the feeling I was getting, so thanks for the confirmation. I can't quite figure out why an oil change might initiate this sort of thing, but hey, why not. Do you see any issue in driving it while I work on getting a new sensor? We're expecting a new child literally any day now and I don't want to be stuck on the side of the road on our way to the hospital

geordi · **Posted:** Sun Aug 25, 2013 1:54 am

Congrats on version 2.0, I hope you have a successful deployment day!

The light is perfectly safe to ignore. Like I said, you would already know you had a problem if there was a real one... This engine does not tolerate oil issues politely OR for very long. Your first and only warning will be unhappy sounds from the engine, that light wouldn't prevent anything from happening.

Simple fact: The oil fill for the engine is 7 quarts (with a slightly-larger M1-301 filter) and the filter holds just about a quart. With the oil pickup leading directly into the oil pump, and then the filter being the next thing in the pathway, and the sensor at the EXIT of the filter... As long as there is 1.5 quarts or so in the pan, *just enough* to fill the filter and keep the oil pump busy... That light will think all is well.

Sadly, the rest of the engine will have already died before that light helps you out honestly.

cerich · **Posted:** Sun Aug 25, 2013 7:17 am

I had the same problem once and it was a bad oil filter. Change that first.

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

Thanks for the info. I certainly feel better about not being stranded or something

kjjet · **Posted:** Sun Aug 25, 2013 10:42 am

I agree its most likely a sensor. Could be a bad filter. Take no chances that you are starving your engine from oil. Do not drive and limit running until you find the problem. Its unlikely that your oil pump is weak. But it could be. That would not be a chance i would take.

Good luck
KJJET

MRausch82 · **Posted:** Sun Aug 25, 2013 11:41 am

What oil filter are you running?

geordi · **Posted:** Sun Aug 25, 2013 11:48 am

First time I've ever heard that the oil filter might be a cause of this... I suppose if it is too restrictive, that is certainly possible, but the oil pressure on a cold engine exceeds 100 psi in the main oil gallery. On a warm engine, the pressure at idle can be as low as 18 psi. Your filter shouldn't be holding that back enough to trip the less-than-10-psi sensor... But I'm open to the possibility.

I got my pressure numbers while running the M1-301 filter, so maybe that might help you out.

edit:

After discussing with Papaindigo, if this all transpired shortly after an oil / filter change... Are you certain that the oil and filter are good for the CRD? Which filter did you use? Which oil?

I'm still leaning toward the sensor being the culprit, but it is possible that the filter was badly manufactured (bad quality from China? :shock:

The shock and surprise!) and that is causing your problem.

Since you will lose a fair amount of oil while trying to change the sensor or the filter... It might not be the worst idea to try swapping the filter first (and top off the oil) and see if anything changes... Then go for the sensor. Or, the best idea might be to hang it all and start fresh. New oil (Mobil 1 Turbo Diesel Truck or Shell Rotella T6 5w-40) new filter (Mobil 1 M1-301) and a new sensor.

If you have driven more than about 10 miles already with this light on... Then that seals it for me - it will be the sensor. I barely got 20 miles out of my second engine with the bottom end failure, and that was FULL of oil and never lost pressure (measured in the main gallery). Meanwhile, engine #1 failed about 8 miles into a test drive after the turbo failed and it had lost a gallon of oil (which I refilled) but obviously the damage was done within the 30 seconds of the turbo failing until I cut it off.

If it was a serious oil starvation issue... I would think you would know already.

papaindigo · **Posted:** Sun Aug 25, 2013 1:34 pm

Thoughts after an offline PM chat with geordi:
1. normally I'd agree without half thinking that the problem is with the sending unit (once had a sending unit failure on a Plymouth minivan back in the day when they also came with a gauge that said pressure was fine - fixed Christmas eve on the road by a nice NC DCJ dealer) but that gauge runs ca. $50 so maybe a bit of extra thought is in order.
2. since this apparently occurred immediately after an oil and filter change I'd wonder about the viscosity of the oil used (5w-20/30 might cause this) or the quality of the filter (even a brand name one can be bad and if restricted and the interior popoff doesn't work right could produce a low pressure reading). This suggests that redoing the oil and filter change might be worth it especially if you have like a Fumoto drain valve and can salvage most of the oil in which case you are out ca. $8 for a new filter plus a bit for lost oil in the process.
3. how much oil did you put in? A full fill on a stock filter is ca. 6.3qts vs 7qts on an oversize filter. Too little oil might cause the problem.
4. it's not impossible that the oil pump is having issues or the screen, assuming there is one, on the oil pump is clogged.

Do you have access to someone who could pop the sending unit and briefly insert a mechanical gauge to check actual readings? The OEM sending unit does send actual readings according to MrMopar64 but I don't know how to access those readings, if the unit is bad the readings would also be bad, nor do I know how to electronically test the sending unit.

Perhaps a more electronic inclined forum member knows of a test. I know the FSM speaks to some sensor tests but have no clue if any of them check sensor accuracy.

geordi · **Posted:** Sun Aug 25, 2013 1:48 pm

Lol - I was editing at the same time you posted that. Great minds think alike.

Harbor Freight sells a mechanical oil pressure gauge set that will thread in where the sensor is. I think it is like $20 or so, and will give you an actual reading instantly.

And an oil bath as you are installing / removing it.

The oil pickup does have a screen on it, the pickup is about 3 inches across and the holes are 1/16" in diameter. If you have plugged that... You have MUCH bigger problems on your hands. 99% certain, that is not your issue.

Low viscosity oil could certainly flow too quickly to develop the proper backpressure, use only a quality CF-4 or higher grade pure synthetic oil. Mobil 1 "Delvac 1" (Silver bottle) or Turbo Diesel Truck (same product) OR Shell Rotella T6 (Blue bottle) are the most readily available, use a 0w-40 or (more commonly available) 5w-40 for these diesels.

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

I've had my doubts about the filter. I used M1 0w40 oil, but at O'reilly they only had microgard (or something along those lines) which sized up to the CRD in their manual, but seemed like a smaller filter than the M1 that I used previously.

I suppose I will start with a new oil/filter change and go from there. Interestingly, at cold start there is no light and it only comes on after running for 5 min, or so, and turns off when I rev it to higher RPM. That seems like it would make sense if it were a flow issue to me.

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

Okay, so oil and new filter (M1 301 this time, same M1 0w40) and still light after it heats up at idle. I think I'll have to give up on trying to fix it on my own with the new baby coming and all. It'll have to go to the shop I fear...

geordi · **Posted:** Sun Aug 25, 2013 9:09 pm

Save your money for the baby... You will need it.
I don't know from personal experience, but I've heard that owning a Jeep is cheaper than owning a baby. :-)r

Anyway - Changing the sensor is EASY. You were looking right at it when you changed the oil filter, and the installation is the same process. Unscrew, plug hole with finger, put new one against finger, slide over and screw in. Hopefully you won't end up wearing too much oil, or you can capture it in a clean can and pour it back in the top.

It is about a 10 minute job if you realllllly nurse the beer.

Please save yourself the heartache of taking it to a dealer, they will do anything they can to screw it up and rob you blind. I'd honestly expect them to tell you that the engine, all 4 tires, the seats... and the RADIO are all combined causes of this sensor light, and everything BUT the sensor will need to be replaced.

MRausch82 · **Posted:** Sun Aug 25, 2013 9:48 pm

I agree. Try replacing the sensor, or get the harbor freight oil pressure gauge kit and see what the readings are. I suspect that the sensor has failed. Get a Mopar unit. I have never had much luck with aftermarket oil pressure sensors on any vehicle I have owned, but maybe that is my luck...

06PeakBagger · **Posted:** Wed Oct 02, 2013 1:43 pm

Congrats on the Baby! Did changing the sending unit sensor fix the issue? The Mopar part number is 56028807AB. I think..

drumedic · **Joined:** Tue Apr 19, 2011 3:24 pm **Posts:** 11

Thanks, having a new daughter is certainly a life changer.

I replaced the sensor and haven't had a single issue with it since. Which is good, I don't think I could handle another issue to take care of right now. Thanks for all the help & advice.

SargeIndustries · **Posted:** Wed Oct 02, 2013 3:20 pm

Same thing happened to me. Replaced filter and problem went away...

Oil pressure light at idle

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