Oil light on at idle

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Started yesterday. My oil light is coming on at idle now. Everything still runs just fine and no noises. It was about a quart low but I topped it off but still comes on at idle up to about 1k rpm's. Above that and the light goes off. I've been using Rotella synthetic 5w40. Anyone encountered this?

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

My CRD Grand Cherokee had the same problem. A new oil pressure idiot light sensor switch fixed the problem.

geordi · **Posted:** Sat May 05, 2012 11:31 pm

Yup, bad sensor. The sender is WORTHLESS for telling you anything about your engine. When that light comes on, either your engine is already in pieces on the roadway under you... Or the sensor is bad.

warp2diesel · **Posted:** Sat May 05, 2012 11:33 pm

Test the oil pressure with a gauge, the sensor can go bad and lie.
My test gauge is a 100PSI gauge scrwed into a brass 1/8" NPT coupling
that is attached to a 1/8" NPT grease gun hose.
Remove the sensor and screw in the test gauge, start the engine and read the pressure.
20PSI at idle with a hot engine is normal, if that is what you have, the sending unit is junk.

geordi · **Posted:** Sun May 06, 2012 12:10 am

He doesn't need to test the sender like that, although he might want to try (and bathe in oil for the fun of it) just for giggles. I know for FACT that his sender is junk, because he didn't follow his question with a comment that the engine has seized. Our engines do NOT accept oil problems politely. If you had a problem, you would KNOW IT already. The time to detect a real problem in order to save the engine is mere seconds. Miss those seconds, and you lose the engine. Period.

We have a mechanically driven oil pump. I'm not crazy about the low pressure at idle, measured from the main oil gallery that feeds all the cylinders and the turbo, the pressure is about 15psi (as low as 12) at idle in gear.

The thing is, that sender is located at the output of the filter. The filter is the SECOND thing the oil touches after being sucked from the pan - The first is the pump. What this means is that as long as there is enough oil in the pan to be sucked up and shoved into the filter (so about 1-1.5 quarts or so) then that sensor will NEVER TRIP and tell you anything.

The proof of this? I blew my turbo way back when, and lost a full GALLON of oil into my exhaust in about 30 seconds. That idiot light never came on. I trusted that "well, since I never saw the low oil pressure light, everything must be OK" and replaced the turbo, refilled the oil.

On the test drive, less than 10 miles - The #1 cylinder broke up, the rod inverted, and punched a gaping hole in the oil pan. The oil pressure light STILL didn't come on, even as the oil was being blasted onto the street!

This thing is as useless as a water detector on the keel of a ship.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Well I hope it is just the light. I went ahead and chainged the oil today to be on the safe side. I am one of those guys that used to think that because it is a diesel and I use synthetic that I can go much longer between oil changes. I got to thinking today that the oil filter may be somewhat clogged. I usually go 8K between changes on the rotella and top grade filter. That has worked for me for 2 and a half years and about 45k miles. Last oil change I used a Fram premium. That was the only difference and possibly made the difference in this case. Anyhow I changed it today and it idled for an hour afterward and no light. I'll do some test driving and see if that was it. Thanks for all the input.

dkenny · **Posted:** Sun May 06, 2012 4:47 pm

any chance you had the oil tested?
results??

Otherwise..I might have to change my wife's jeep oil changes..

while I don't use Fram for the filter..the rest has my attention..I run about 10K between changes..using T6 oil..

I have not problems changing..oil does make fuel...

-dkenny

warp2diesel · **Posted:** Sun May 06, 2012 4:55 pm

geordi wrote:

He doesn't need to test the sender like that, although he might want to try (and bathe in oil for the fun of it) just for giggles. I know for FACT that his sender is junk, because he didn't follow his question with a comment that the engine has seized. Our engines do NOT accept oil problems politely. If you had a problem, you would KNOW IT already. The time to detect a real problem in order to save the engine is mere seconds. Miss those seconds, and you lose the engine. Period.

We have a mechanically driven oil pump. I'm not crazy about the low pressure at idle, measured from the main oil gallery that feeds all the cylinders and the turbo, the pressure is about 15psi (as low as 12) at idle in gear.

The thing is, that sender is located at the output of the filter. The filter is the SECOND thing the oil touches after being sucked from the pan - The first is the pump. What this means is that as long as there is enough oil in the pan to be sucked up and shoved into the filter (so about 1-1.5 quarts or so) then that sensor will NEVER TRIP and tell you anything.

The proof of this? I blew my turbo way back when, and lost a full GALLON of oil into my exhaust in about 30 seconds. That idiot light never came on. I trusted that "well, since I never saw the low oil pressure light, everything must be OK" and replaced the turbo, refilled the oil.

On the test drive, less than 10 miles - The #1 cylinder broke up, the rod inverted, and punched a gaping hole in the oil pan. The oil pressure light STILL didn't come on, even as the oil was being blasted onto the street!

This thing is as useless as a water detector on the keel of a ship.

An old saying, "Trust but verify".
Another reason to have an oil pressure gauge.
Save You Faith for Spiritual Endeavors.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

dkenny wrote:

any chance you had the oil tested?
results??

Otherwise..I might have to change my wife's jeep oil changes..

while I don't use Fram for the filter..the rest has my attention..I run about 10K between changes..using T6 oil..

I have not problems changing..oil does make fuel...

-dkenny

I caught the oil in a couple of old rotella jugs. It would only have a little residue of "new" rotella in them. I'm not sure where to have it tested though. As far as the Fram filter. That was the first time using that one. It was an "impulse buy" as they say. I bought the rotella at walmart $19.95/4qt jug but they didn't have my usual purilator so I bought the fram tough guard brand. It may be that it caught too much debri and wasn't letting enough oil pass through when it idled. Does that sound possible? Today's change, I went with my usual T6 rotella 5w40 and back to the purilator filter.

Joe Romas · **Posted:** Sun May 06, 2012 7:01 pm

Oil test or not doesn't the manual calls for 6k oil changes. I don't put a lot of miles on mine and change it every 6 months at about 4k :SOMBRERO:

There's been too much bad written about Fram filters for me to trust one on anything I own :banghead:

geordi · **Posted:** Mon May 07, 2012 1:32 am

I use the very good Mobil One M1-301 filter, which is an "oversized" filter for our engines. It will mount right up and increase the oil charge to a full 7 quarts, eliminating the nonsense of measuring out 6.4 with the stock filter size. As for the oil change interval... Get this: I changed my oil at 120k or so, and decided that I was going to run a shorter change for a while to check the difference. I have no EGR or CCV getting in the way, and I use Rislone now starting with that change.

At 123k or so, the turbo started acting sluggish, seeming to have more turbo lag on take off from a stop. I decided to change the oil again. The problem vanished. I'm now at 127k, and it was very laggy again, until I changed the oil yesterday... It is running great again.

I think that I will be investing in an oil-scrubbing centrifuge next. Warp, care to offer any tips on yours? Can it discharge uphill, like into the oil fill tower on top of the intake?

Sent from my iPad using Tapatalk HD

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Well my hopes of it being a clogged filter were shot down. At full operating temp after driving around town for a while the oil light is coming on again at low rpm's (1000 or less). I will swap out the sending unit and hope this is the problem. Any advice on this procedure? Do I need to drain the oil first? Is it located on the filter housing?
Thanks,
Steve

turbobike · **Posted:** Mon May 07, 2012 2:01 pm

Sender is an easy change (I'm on my 3rd one)
It's right near the oil filter. Hardest part of the job is disconnecting the wire without breaking the connector.
No need to drain the oil,,,,but you will lose a little bit, depending on how fast you put the new one in.

warp2diesel · **Posted:** Mon May 07, 2012 5:44 pm

geordi wrote:

I use the very good Mobil One M1-301 filter, which is an "oversized" filter for our engines. It will mount right up and increase the oil charge to a full 7 quarts, eliminating the nonsense of measuring out 6.4 with the stock filter size. As for the oil change interval... Get this: I changed my oil at 120k or so, and decided that I was going to run a shorter change for a while to check the difference. I have no EGR or CCV getting in the way, and I use Rislone now starting with that change.

At 123k or so, the turbo started acting sluggish, seeming to have more turbo lag on take off from a stop. I decided to change the oil again. The problem vanished. I'm now at 127k, and it was very laggy again, until I changed the oil yesterday... It is running great again.

I think that I will be investing in an oil-scrubbing centrifuge next. Warp, care to offer any tips on yours? Can it discharge uphill, like into the oil fill tower on top of the intake?

Sent from my iPad using Tapatalk HD

My 55 GPH Centrifuge was purchased from PA Biodiesel Supply. http://pabiodieselsupply.com/shop/waste ... c-100.html and bought or made the rest of the parts I needed. I used a 1" NPT Nipple, a 1" conduit nut and lots of JB Weld after cleaning to attach the drain fitting into the side of the sump and it still works.
If you want to discharge into the top of the engine, you will need to shell out for the system with a recovery pump. Try: http://www.dieselcraft.com/engine-oil-cleaning.php
Just remember, gravity is still free and even the Europeans have not figured out how to tax it yet.
If you can figure a way to mount the centrifuge on top of the valve cover and close the hood, installation will be easy.
Good Luck

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Update: The oil light and dinging is on all the time now no matter what rpm.

warp2diesel · **Posted:** Mon May 07, 2012 7:12 pm

TennesseeCRD wrote:

Update: The oil light and dinging is on all the time now no matter what rpm.

Did you change it out yet?
If so you could have a loose connection between the sender and ECM.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

warp2diesel wrote:

TennesseeCRD wrote:

Update: The oil light and dinging is on all the time now no matter what rpm.

Did you change it out yet?
If so you could have a loose connection between the sender and ECM.

Nope, haven't had time yet. Is this an auto parts store part or dealer part only? I'll order it tomorrow.

papaindigo · **Posted:** Mon May 07, 2012 8:25 pm

Looks like the part # is 56028807AB and when you Google that # it appears to be a pretty stock Jeep sensor which is not much of a surprise. Looks like dealer or parts store price is like $40.

FYI I had one just flat die on me years ago on an early Plymoth minivan back when they had an idiot light and an oil pressure gauge. Idiot light sensor died and light up idiot light but gauge said I had good pressure. Drove to small town Chrysler dealer nearest to interstate and they did a warranty replacement at light noon the day before Christmas.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

papaindigo wrote:

Looks like the part # is 56028807AB and when you Google that # it appears to be a pretty stock Jeep sensor which is not much of a surprise. Looks like dealer or parts store price is like $40.

FYI I had one just flat die on me years ago on an early Plymoth minivan back when they had an idiot light and an oil pressure gauge. Idiot light sensor died and light up idiot light but gauge said I had good pressure. Drove to small town Chrysler dealer nearest to interstate and they did a warranty replacement at light noon the day before Christmas.

Cool. That part number helps alot. Got a local dodge dealer that I have dealt with for our work trucks but they don't employ the sharpest tools in the shed there.

geordi · **Posted:** Mon May 07, 2012 10:38 pm

I bought my replacement sensor for $40 right off the shelf at an Autozone.

Thanks for the info Warp, I just didn't want to have to drill and tap the pan for a drain. I found what looks like a GREAT spot to get it to feed from however, the hex cap on the oil pan is a high-pressure line.

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Oil light on at idle

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