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Discussion Starter · #1 ·
I have recently bought a high mileage (or kilometrage more accurately) Grand Cherokee Limited 2.7 CRD 5sp auto, which until yesterday had been running fine. She has a little over 200k on the clock.

After a day out with about 150 miles driven I returned home via a nasty, steep hill road (rural area of Spain) and had to stop almost at the top of the hill because of a car leaving a driveway ahead of me. Vehicle was very nose high. I engaged handbrake and set box to P as normal and noticed that the oil pressure gauge (which had been fine before) immediately dropped to zero and the "Check gauge" warning light came on. Engine sound was not unusual or changed, temperature gauge was normal..

I pulled the car off the road onto a flat area and left it to cool (engine was noticeably hot). When cool I rechecked the ignition and the gauge still stays zero (needle does not even flickere). Oil level in the engine is fine and there is no sign of oil leakage on the engine or the roadway. This morning I checked again and still no movement in the gauge and no leaks.

There are a bunch of old posts here, but few about the 2.7l CRD, that identify the sender unit as the probable culprit, but any thoughts on the likelihood of a faulty or blocked oil pump? Is stopping it for 3 or 4 minutes with the front way higher than the tail potentially going to draw any gunk in the sump into the pump? I am loathed to try starting or moving the vehicle without a better idea of the risks.

Any help or ideas appreciated. My previous truck was a 2.6l 1989 Mitsubishi which I could maintain with a screwdriver, a hammer and a basic socket set, the sheer complexity of the Jeep is a new thing to me.
Rob
 

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I have recently bought a high mileage (or kilometrage more accurately) Grand Cherokee Limited 2.7 CRD 5sp auto, which until yesterday had been running fine. She has a little over 200k on the clock.

After a day out with about 150 miles driven I returned home via a nasty, steep hill road (rural area of Spain) and had to stop almost at the top of the hill because of a car leaving a driveway ahead of me. Vehicle was very nose high. I engaged handbrake and set box to P as normal and noticed that the oil pressure gauge (which had been fine before) immediately dropped to zero and the "Check gauge" warning light came on. Engine sound was not unusual or changed, temperature gauge was normal..

I pulled the car off the road onto a flat area and left it to cool (engine was noticeably hot). When cool I rechecked the ignition and the gauge still stays zero (needle does not even flickere). Oil level in the engine is fine and there is no sign of oil leakage on the engine or the roadway. This morning I checked again and still no movement in the gauge and no leaks.

There are a bunch of old posts here, but few about the 2.7l CRD, that identify the sender unit as the probable culprit, but any thoughts on the likelihood of a faulty or blocked oil pump? Is stopping it for 3 or 4 minutes with the front way higher than the tail potentially going to draw any gunk in the sump into the pump? I am loathed to try starting or moving the vehicle without a better idea of the risks.

Any help or ideas appreciated. My previous truck was a 2.6l 1989 Mitsubishi which I could maintain with a screwdriver, a hammer and a basic socket set, the sheer complexity of the Jeep is a new thing to me.
Rob
The good book says. "STANDARD PROCEDURE - CHECKING OIL PRESSURE

(1) Remove engine cover (Refer to 9 - ENGINE - REMOVAL).
(2) Remove oil galley plug together with seal at timing case cover.
(3) Screw oil pressure gauge adaptor fitting together with seal onto timing case cover.
(4) Connect oil pressure gauge to adaptor fitting.
(5) Check oil level, adjust with correct engine oil if necessary.
(6) Insert temperature of remote thermometer into oil level indicator tube.

WARNING: USE EXTREME CAUTION WHEN ENGINE IS OPERATING. DO NOT STAND IN A DIRECT LINE WITH FAN. DO NOT PUT YOUR HANDS NEAR PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHES. "

CAUTION: Ensure that fan and accessory drive belt DO NOT damage oil pressure gauge hose.
(7) Start engine and bring to operating temperature 90°C (194°F).
(8) Record engine oil pressure at idle.
(9) Raise engine speed to 3000 rpm and record oil pressure. Fig. 2 ENGINE COMPARTMENT 1 - COOLANT PRESSURE CONTAINER 2 - ENGINE COVER 3 - RADIATOR WG ENGINE 9a - 3 ENGINE - 2.7L DIESEL (Continued) (10) At normal operating temperature the oil pressure must not drop below 3 bar (44 psi.). When engine speed is raised, oil pressure must rise with out delay and be no less than 3 bar (44 psi.) at 3000 rpm.
(11) If oil pressure is out of range, determine cause.
 

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Failed sending unit is a quite common thing on the WJ CRD. And aftermarket ones do fail 5x faster than OEM.
@Delta0 is right that the only way how to check is to measure with an analog gauge
The oil pressure sender is mounted on an adapter where is also oil feed for turbo. This adapter is a fancy alluminium thing
bolted to the block. The channels inside are quite thin. With age and lack of maintenance a lot of debris/gunk can accumulate inside and block the
passage to the sender. So clean it thoroughly when you are in. And you can also use this port to tap the gauge. I think it has a 1/4NPT thread
Which oil viscosity you are running? 5W30 is good in winter or in cold climate areas. For Spain consider 5W40 or 10W40 rated for HD diesels
 

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if you did not know where.
I am guessing as you did not mention tapping, knocking ticking its likely a sensor issue - any code ?

skjeep - good to see your OK (y)
 

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if you did not know where.
I am guessing as you did not mention tapping, knocking ticking its likely a sensor issue - any code ?

skjeep - good to see your OK (y)
My jeep had no nasty noises
when the gauge stopped working.

I guessed it was a sensor fault,
and carried on using it.

Before long, the engine seized.
 

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Discussion Starter · #6 ·
Thanks for the replies, I managed to track down a mechanic with an "off site" pressure test tool who is coming out to check the sender unit. Not an easy search that, every garage has a test kit, but virtually all of them are linked to an onsite diagnostic computer and not available "off site".

if you did not know where.
I am guessing as you did not mention tapping, knocking ticking its likely a sensor issue - any code ?
Thanks for the image, that really helped. No awful sounds that I can identify. But this is my first Diesel and first Automatic in 40+years driving so everything sounds odd to me currently.
I've not been able to access codes via the ignition key switching yet, I am considering buying one of the bluetooth diagnostic plugs to access them.
 

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good luck - let us know what the true oil pressure is. 🤞
 

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Discussion Starter · #8 · (Edited)
Finally had my WG formally checked at the shop today after its "interesting" Oil Pressure Issue. Turns out the plastic body of the sender was melted, but the thing was still functioning correctly.
Drinkware Musical instrument Natural material Jewellery Artifact
Automotive lighting Bumper Font Wrist Electric blue


Unit was the original from 2003 and has been replaced with a new OEM part.

More worrying is the feedback from the pressure test.
Cold Idle: 2.5 bar (36 psi)
Hot Idle: 1.2 bar (17 psi)
Hot 3000 rpm: 5 bar (58psi)

Mechanic is asking how deep my credit line runs.....:eek:
 

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Why have you changed the sensor if it was still working correctly?

That pressure values are not good? 🤔
 

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SPEC for oil pressure
At normal operating temperature the oil pressure must not drop below 3 bar (44 psi.). When engine speed is raised, oil pressure must rise with out delay and be no less than 3 bar (44 psi.) at 3000 rpm At normal operating temperature the oil pressure must not drop below 3 bar (44 psi.). When engine speed is raised, oil pressure must rise with out delay and be no less than 3 bar (44 psi.) at 3000 rpm .
 

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Discussion Starter · #11 · (Edited)
Changed the sensor because in melting it had fused itself to the mounting, getting it off destroyed it. I bought the OSM replacement on the assumption that the sensor was the problem. Which it actually wasn't.

For the CRD the 3000 rpm reading is fine, but the others are pretty bad. Driveable but will need a full strip down very soon to find out where it is losing pressure.
Faulty pump would be the "best" outcome, bearing clearances seem more likely given the 200k+ mileage though.
 

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I would not touch the engine, I would use it as is…
A friend of mine with the same engine is now at 350.000 kms…

which oil are you running? 10w40, or 5w30?
 

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were those oil pressure readings taken with a GAUGE or the dash readings?
 

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1.2 at hot idle is pretty low, but still acceptable
If still running 5w30 change to 5w40 or 10w40.
Use heavy duty diesel truck oil like Ravenol NDT or similar
for Spain id even consider a 15W semi synthetic oil
 
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Discussion Starter · #15 ·
were those oil pressure readings taken with a GAUGE or the dash readings?
Those are actual gauge readings taken via the sender port. 10W40 Oil, level is full and less than 2 months old.

I am concerned about the Cold Idle reading. For the 2.7l CRD I see a recommended pressure of 4 - 5 Bar (60-70 psi) but mine is half that.
The Hot Idle 1.2 Bar (17 psi) is marginally toward the low end of the recommended range and the 3000rpm reading is slightly high 5 Bar (70 psi)

Seems to my line of thought that the oil pump is struggling to generate pressure at low engine revs, so a blockage or wear issue?
 

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Those are actual gauge readings taken via the sender port. 10W40 Oil, level is full and less than 2 months old.

I am concerned about the Cold Idle reading. For the 2.7l CRD I see a recommended pressure of 4 - 5 Bar (60-70 psi) but mine is half that.
The Hot Idle 1.2 Bar (17 psi) is marginally toward the low end of the recommended range and the 3000rpm reading is slightly high 5 Bar (70 psi)

Seems to my line of thought that the oil pump is struggling to generate pressure at low engine revs, so a blockage or wear issue?
Where I come from, a low oil pressure
shows a high flow rate round the engine.

Have you checked your oil pressure relief valve?

It could be that your OPR is knacked.

I'd try a new spring, and a new valve.
 

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I agree with Delta - don't give it up. As Monty Python says 'I ain't dead yet'

as mentioned pump and bypass. lets try simple, easy hail marys before tearing into eng
oil type brand and weight ............. let the battle begin. :)
oil FILTER brands matter.
Add RISLONE oil treatment - my go to for sludge varnish deposits. 🤞

Then when you change the oil - give it a close look - see what heavy particles are on bottom of catch pan...
 
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I agree with @Delta0 and @jtec, oil filter can cause a little drop in oil pressure.
I had experienced Mopar filters and a super-high-space-stellar-racing K&N filter: with the first one pressure is a bit more higher, and in my opinion filter efficiency is exactly the same 😂
 

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Discussion Starter · #19 ·
Yes several possibilities to eliminate before tackling the most serious potential culprit.
Start with the cheapest option first. Will be an ongoing process........
 

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to the oil filter.... 2,7CRD does not have a conventional spin-on filter. It uses a paper cartridge. There is a dorn clicked onto filter housing cap and going thru that cartridge.
It protrudes below the cartridge. There are 2 O-rings on that dorn. If bottom (smaller) one is missing or worn, you will have a low oil pressure on idle.
If the middle one is missing then your oil filtering will be compromised If the dorn is broken or missing, then it will not work at all.
Good quality filter cartridges contain all 3 o-rings in the package. 3rd o-ring is for the cap itself.
 
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