Well now I have a perplexing problem and I need help.

Start the car in the morning and drive the 1/4 mile to the main road. When stopping the oil light comes on for 5-8 seconds. Once the car is driven several miles and the engine is warm the light never comes on again.

Checked oil level and everything seems to spec. Changed oil pressure switch and changed oil and filter with no improvement.

On a hunch I started the car cold and repeated the exercise but when the light came on I immediately shut off the engine and took a dip stick reading.

The oil showed down 3/4 of a quart. It's possible it was even lower just befor shutting off the engine. It did take time to get to the dip stick and get a reading For an engine with 45K miles on it this seemed unusual. I'm using 5-30 Castrol Syntek.
Any thoughts would be appreciated.
JS

 

hm... It seems like you might have something clogging your oil pump or your oil pump might not be able to pump while it's cold. I would just drive it and see if those could possibly be what's causing your problem because getting to the oil pump requires removing the oil pan which is a real pain.

 

(I've moved your thread from the X-Type section to the XK8/XKR section)

As well as changing the oil pressure switch, did you check the harness for damage?

Also, are you using an oil filter with a non-return valve? The OE Jaguar filter has this fitted. Several aftermarket filters that physically fit don't have the valve.

Graham

 

The low pressure indicated during warm up only is unusual, it usually happens when the engine is hot if there is a real problem. I suggest looking into an electronic overlap with a sensor that is temperature related, such as a coolant temp sensor or a heated O2 sensor. You also may have a CAN bus problem in the instrument pack where the CAN is headquartered. To be sure, get the oil pressure tested with a mechanical guage before doing anything else.

 

Thanks for the suggestions. I've ordered an 1/8" NPT Female To M10x1.25 Male adapter for a manual oil gauge. It should be here Friday and I can take a true reading over the week end. I wish I could find the reverse adapter so I could run a "T" fitting and check the light response against the gauge.
What advantage would a check valve in the oil filter provide?
Thanks,
JS

 

The valve prevents the oil from draining keeps the filter full.
So when you start the car there is not a delay in oil flow to the engine while the filter fills up.

 

The low dipstick reading immediately after shut down is normal- it takes time for the oil to return to the sump. Your owners manual should describe the correct manner for taking oil level readings.

I'd investigate the reason for low oil pressure when cold, this is not normal at all.

 

My concern is that the oil pump is getting starved due to lack of oil returning to the pan. Hot oil would drain easier so the problem would disappear once the engine was warm. An engine with only 45K miles shouldn't have sludge or anything blocking the returns.
What is the second sensor adjacent to the oil pressure switch?
Thanks,
JS

 

If this was a factor, all engines would exhibit the same problem. The fact that your dispstick indicates only 3/4 quart low immediately after shutdown proves there is no such problem. Cars typically would have to be 3-4 quarts low before the oil pump starts sucking air, especially when stopped and the engine at idle.

You mentioned using 5W30 oil, the '5' being the winter rating. This is what I use in my car with virtually identical engine and experience no oil return problems even in -35*C winter temperatures. In the short time it takes to start a car and drive even 1/4 mile, the oil is well on it's way to normal operating temperature, long before the coolant gauge awakens.

 

Unlike older models where the pressure relief valve was next to the filter housing, the V8 oil pump has an integral pressure relief valve which regulates pressure to 65.25 lbf per square inch.

If this valve is not seating properly (physical damage or dirt), it would cause low pressure.

You need to measure the actual pressure to determine whether there actually is component failure.

Graham

 

Had a similar problem on mine at 43000 miles, if the car was parked for a few days sometimes it took up to 20 seconds for the oil light to go out after a cold start other times it was OK. It never lit up during normal running or warming up. I changed the oil pressure switch and no improvement then I had a close look at the push on electrical connector that goes onto the switch and noted some green/blue corrosion, after a thorough soaking with contact cleaner the problem cleared and has not returned in over 12 months.

 

The car started life in this country in NY City. The possibility of corrosion from road salt is a good thought. I did inspect the connection when I changed the switch but there is always a chance I missed some. In any case it sounds like the next step is checking the true pressure which should happen early next week if the adapter arrives.
I'll keep you posted on the results.
Thanks,
JS

 

I have custom manufactured M10x1.25 x F10x1.25 x 1/8 NPT tee adapters for use in the RealGauge kit (see my website below). I can sell the adapters + hardware for $65 shipped. PM me on the forum or contact me from my website if you are interested.

 

Finally got the m10x1.25 to 1/8NPT oil gauge adapter on Saturday so I could take an oil pressure reading from col start up. When starting, the pressure immediately goes to approx. 70 psi. As soon as you touch the gas and return to idle the pressure drops to 4-5 psi. Raising the idle slightly brings the pressure back to 70 psi. When up to normal temperature and sitting at an idle the pressure sits steady at 15-18 psi.
At this point, I'm of the opinion the problem is the pressure regulator valve in the oil pump sticking when cold, meaning an oil pump replacement. Any less expensive suggestions for cures would be appreciated.
Thanks,
John S.

 

I think you diagnosed it. It is unusual for the bypass valve to stick, but that is probably what happened.

 

Not necessarily. If the regulator valve is of the piston in a bore type they sometimes hang because the bore or piston is scored. You take it apart, polish the offending piece and re-assemble. Use a *new* cotter pin in the largest and highest quality that will fit during reassembly. If this cotter pin lets go, all oil pressure dumps back into the pan.

The engine diagrams appear to confirm that it is of that type. Unfortunately it is driven by the engine crank and located behind the front engine cover.

The engine repair course manual in pdf form previously posted by Motorcarman will be helpful to you in the procedure. It is not for the 4.2, but most of it applies.

BTW, you can do a remote mount for the oil pressure gauge by buying a turbo oil hose kit on ebay. It has an oil restrictor, a M10x1.25 banjo at the engine end, stainless braided hose, and a tee at the remote end. $25 to $35 depending on hose length.

 

In order to repair the valve in the oil pump you need to remove the pump. I don't know about you, if I have to remove the pump to repair it I'm going to replace the whole pump, on general principle. If the valve is sticking after only 45K miles it could be a manufacturing issue. If I'm going to put that much work into the repair I'm going to replace it. The dealer will cover the guarantee on the repair and I get to drive a 2012 XF in the mean time. I hate to pay the dealer prices but they have been good to me so far.
Thanks for the feedback,
John S.

 

The suggestion was made purely on the premise that you were sincere in your request for "less expensive suggestions" with regard to replacing the oil pump.

Other people have freed up hung pressure relief valves with no ill effect. Sometimes they even hang during assembly of a oil pump during or after a blueprinting process.

 

Final Chapter,
Had a long talk with the mechanic this AM. According to him when the engines were assembled they had "occasional" problems with assemblers over tightening the oil pickup pipe and cracking them. This would allow the pump to suck air.
Based on this information we decided the first plan of action would be drop the pan and check out the pickup pipe. Well it wasn't cracked. It was loose with one bolt almost completely out. Problem solved.

Thank again for all your input.
John S.

 

John,

Thanks for posting the resolution to this issue.

I've amended the thread title adding 'RESOLVED' to help anyone in future searching for information on oil pressure problems.

Graham