Low oil pressure on start WK2 CRD

[Jeeper6]

Dos any body else get a low oil pressure light on start up with their WK2 VM?

When I start mine from cold after sitting for a day or two, at least half the time I'll hear tappet noise like many engines have before the oil gets to the top of the engine and then it quietens down as the oil gets up.....sometimes it takes a number of seconds.

(I previously used 5w 40 oil, then switched to 10w 40 oil, though they do flow similarly so it isn't oil viscosity)

The low oil light comes on as well as sometimes a warning in the middle of the speedo reading "Engine Low Oil Pressure"
It's been doing this since I bought it so nothing new...and nothing detrimental so far.

It doesn't do it of course when warm, and also doesn't do it at every cold start.

The Oil Pressure sensor is only a basic on / off switch I think. No or low oil pressure and it will send a warning, but once pressure is established it obviously opens or closes the circuit so the oil pressure light goes off.
(I have the dash setup to SRT so can display all the same gauges as the SRT does. If I do display the oil pressure it only reads 1 bar until about 2000rpm then will show 2 bar. The OBD readout port does not have an oil pressure reading at all, so gather actual oil pressure readings are unavailable on this engine?)

I had the oil cooler replaced a few months ago, but it was doing this with the old cooler, and now same with the new one...the oil temp sensor and pressure switch I am sure are in the oil cooler / filter assy, so was replaced with new ones that came with the cooler.
I stupidly threw out the old oil cooler assy before examining it and learning a bit more about it....like where to fit a proper pressure sensor!

Many engines have "anti drain back valves:" in or near the oil filter to prevent "dry" starts. From what I can see there is no real anti drain back valve in the oil cooler / filter set up on these things.

I know oil is pumped to the bearings first before it gets to the upper oil galleries, but that is after it goes through the filter, (and oil pressure switch I assume), and there should always be residual oil between the crank and bearings anyway...but curious to know if anybody else experiences this?

Or has anybody fitted an oil pressure switch that will send pressure readings to a gauge?

[Jeeper6]

I'll see if I can find the thread you mention. Meanwhile I did read somewhere that there may be some sort of "cut off' arrangement...I gather from that, that when the oil pressure gets too high according to the ECU it must alter the pressure somehow which could potentially lead to wild pressure fluctuations....could be totally wrong about that.

I'll have to do some research...always very hard to find much info on these things besides feed back from owners.

Obviously the petrol versions have proper oil pressure gauges, being there is the pressure gauge available in SRT, and a mate has a 3.6 Pentastar, and he set his dash with the SRT readouts and he gets a healthy oil pressure reading.

[LeCheese]

A simple one, but have you checked your oil level isn’t on the low side? My diesel had the oil pressure light come on a few times after a while between starts during the covid lockdowns - checked the oil, it was on the low side, put a few hundred mL in and hasn’t been an issue again

[Jeeper6]

Originally Posted by LeCheese

A simple one, but have you checked your oil level isn’t on the low side? My diesel had the oil pressure light come on a few times after a while between starts during the covid lockdowns - checked the oil, it was on the low side, put a few hundred mL in and hasn’t been an issue again

Oil level is ok. I always keep the level at the full mark, It doesn't use much oil at all, and being the oil is never more than a couple of thousand K's old viscosity is good too.
When I change the oil I put around 7.5 litres in so I know it's full even if the dip stick was wrong.

[drover]

If they did replace the sender and its still dicky like before then could be the wiring, cold mornings, moisture and a few corroded wires can cause a loss of signal, its only mV and not much to eat it away, especially as those connection terminals are not substantial and can be easily damaged, bent or rotted, I would head for a close up inspection of the plug........ like a computer plug very touchy.

No codes, no dramas after ignition then its not a drama I would hazard just an annoyance....... My old HiLux did it, pulled, cleaned and tested everything, changed oil & filters, then got the shits gave it a load of diesel oil and a good burn to work and back for a day or so, 70km round trip at 100kph, dropped the diesel oil out, went back to my truck spare keg and put the Valvoline back in it, all good and been that way for about 10 years now........... any help for you nope but a good story........ HiLux is nearly 20 yrs old now....

[Jeeper6]

Yeah true, but the tappet noise tells me the oil pressure just isn't there straight up...the sender is telling me the pressure is low while it is noisy, then when the low oil pressure light goes out the rattle goes too...

I don't get any codes at all about low oil pressure or anything else related. I guess if there was an oil pressure problem there would be some code thrown telling me so.

I just did a code clear to satisfy myself, nothing there...

I am curious as to whether it's just my Jeep that has the sooty exhaust and the oil thing...mind you it just ticked over 190k and runs like a charm. Just got back from a trip to Noosa North Shore towing the 2700kg van and it returned 14.6 litres per 100km...6.8 k's per litre.
...and that included a belt up the beach in low range at Teewah through soft sand for a work out...

[drover]

Lazy pump on lift then comes good ????
Just thought what oil filter are you using ???
Is the O ring near the filter body or near the end of the tube ??

or this one this is the preferred nowadays.