The only way to resolve this is then to either:
change the bulbs back and see what happens, or
put a mechanical gauge on the oil gallery and see what the pressure actually is.

 

On the front left hand side of the engine, see illustration below. The filter is item #7.

 

I will almost bet that the 2 spots are where the A/C drains are washing accumulated crud onto the floor. Also normal.

 

Mac
his car is a straight 6, not a V12, so i think the breather may be different.

 

My bad. Apologies.

 

crap, missed that..never mind.

 

Still unsolved. I'm getting tired of this now.

Right so, a few people from another forum have said that when upgrading to LED bulbs on the instrument panel, the readers can go crazy. So tomorrow I will change the bulbs back to normal ones.

ALSO, I topped up the coolant recently, maybe too much. I will try taking some out.

When I turn the key, the oil pressure shoots up, the coolant temperature gradually rises as the car gets hot. This indicates a physical problem.

I just have no idea where to look?

I'm so close to giving up but I don't have another car to drive! Please someone help 🤯

Thanks

 

I think you just hearing the refrigerant pressure 'equalizing' in the system.
The compressor usually runs all the time to cool the fuel returning to the tank.
When the system is shut down the pressure 'bleeds' back from the 'high-side' to the 'low-side' with an audible 'hiss'.

 

The hiss is not the issue. High oil pressure and rising coolant temperature is.

 

If you are saying that the oil pressure gauge shoots up, ignition on, engine not running, then the problem is the gauge circuit not the engine. As to the temp gauge, I would be very surprised if that was not similarly misleading you.
What else do you want us to say? Your car may be overheating, but very likely not. Buy a 10 quid remote sensing digital temp reader from ebay and strap the sensor on the top hose and see, for real, what is happening. There are no "turn this one quarter turn anticlockwise and the car will be perfect" - type solutions when sorting out a 35 year old car. If you are up for it, go for it, buy the manuals, get to understand the car and its systems, buy the tools, and have fun doing it and understanding it. If not, and I quite understand this might not be for you, then sell the car and do what you do enjoy doing.

 

I hear you Greg. I love this car but it doesn't suit my lifestyle. I'm 30 I work freelance and need to drive often for work. I have the manuals too, I've decided to put everything to one side for now.
Thank you all for your help

 

But,,, answer the question...pls

Is it that when you put the key to ON, without starting the engine, the guage moves, shoots up, when there should be NO oil pressure? Or, if you start the car,,, is there a difference in the gauge readings that comes with turning on the lights?

It would be good for all of us to know.

​​​​​​

 

Hi sorry I didn't mean to not answer..... Yes, when I turn the key before firing up, the pressure gauge swiftly goes up to 75/85 immediately. It pretty much stays around there.

What made me think that its a true ready is that my Coolant temperature is higher than usual. Its now around N or just above.
Hope that answers the question. When I go back to investigating, I'll definitely let you know the outcome.

 

Well that's great... It's the bulb change.
Good!

 

Then the oil pressure electrical circuit is faulty. Forget the oil gauge the engine is fine. The temp gauge is also misleading you. The car itself is fine. You have probably got a crossed connection where the plugs go into the back of the instrument cluster, and or the LEDs have screwed something.
Stop worrying.

 

Hello Everyone,
I must apologise to you all. Genuinely I was really worried about my car and the thought of damaging the engine, which is what I thought was happening, was upsetting me. I cherish and respect the car and all its mechanics.

SOLVED* Something about the LED bulbs in the instrument cluster was effecting the oil pressure gauge and the coolant temperature gauge. As I mentioned I recently upgraded them, although initially they didn't cause any changes. I have now changed all the bulbs to new, original style bulbs and both gauges have returned to normal. Sorry guys I was worried and acting out of concern
Okay so the lesson here is, if it works don't try upgrading it!!!!!

Thank you all again for your dedication and assistance.

 

Well done and sorted.

FAITH ya gotta have FAITH.

The Jag engines are STRONG, even the 1/2 size version, and rarely give any issues.

My daughters XJ40 3.6, same as yours but Auto, survived a teenage petrol head girl, who asked: "if I dented the floor would the accelerator move any further and give me more speed", OH DEAR. She now be 32, and that car is still running, nuff said me thinks.

 

Your daughter and I are the same age, must have been something in the stars that year

Thanks for responding