DID I SCREW UP SOMEWHERE??
I am starting a new thread on the above topic rather than add it to my post " 1990 xjs: Final check before attempting to start".
Having done all of the preliminary checks, Ignition Timing, Spark and fuel injectors, they all checked out OK.
I mentioned in the above post that I had an oil leak at the pipe above the oil filter. Yesterday, I resolved that by replacing the crush washers so one more item checked off on my list. I also mentioned that I was able to get the oil pressure up by putting an extra 2 quarts of oil in the engine and lifting the rear of the car. Having done that, I lifted the front of the car to get it all level to fix the said oil leak.. I drained out the extra oil I had added and now the level is good.
Fast forward 5 days later, the car is level and I have lost the oil pressure again. I lowered the front of the car added extra oil and I got back the oil pressure.
It seems as if the pump is not sucking oil through the pickup pipe. Both pipes were cleaned and new o-rings installed. I believe the car has a full flow system as it looks like this.


Any idea as to what is causing the 'no oil pressure' issue.
I hope I do not have to drop the oil pan and sandwich plate because if I have to, I will give up on this car and send it to the graveyard because I am too old to work on my back for hours on end. HELP HELP.

 

I am not familiar with the oil pan/oil pump pickup on this car, but if it was a Chev motor, that is a classic symptom of the oil pump pickup way down in the sump coming off the oil pump. You are sucking air, instead of oil, for some rason

Doug

 

When you start the car, does the oil light go out? How long do you run it with nothing on the gauge before deciding it has no oil pressure?

The oil light should go out quickly, but on my car at least it takes a little while for the gauge to start moving.

 

As stated above, I have not started the car as yet. All the tests were performed during cranking. I have now put together all of the components on the car to attempt to start it.
My concern is why when the car is level I have no oil pressure when cranking but if I lower the front of the car I get oil pressure. So, priming the system with the front low, you would expect the system to stay primed when the car is level. However, that is not the case. pump builds pressure with the rear raised. place the car level and the oil pressure is ZERO.

 

Sanchez, that is the bypass system you have if it follows the diagram.
You for sure have a pickup problem. The oil pump in this bypass system is fed from TWO sources:

1. the pickup in the sump and
2. the return from the oil cooler.

My guess is that it is this latter that you have somehow not connected properly. Here are some photos:


Blue ring shows the pump output connections to the oil galleries. Red ring shows (round connection circled) the oil cooler return feed to the pump and (pipe circled) the pipe from the sump pickup joining the casting. The TWO input to the oil pump.

Close up shots.

I think, as you have oil pressure when the sump is tilted up at the back, that the oil gallery feed side is OK (blue ringed).
If either one of the input side connections (red rings) is not connected properly, then there will be no oil pressure to the pump as one of the two is sucking air. This must be your problem as the pump is creating pressure when these two are covered in oil by your tilting.

The pipe from the sump pickup has to be bolted into place (there is a tab on it about halfway along it) and needs an O ring which as the photos show is set into a groove in the casting. Photo here:


You can easily unbolt the bypass fitting from the sump sandwich plate, withdraw it and take a look at it to see if there is anything obviously amiss. It has O rings on it as shown in this diagram



Bypass fitting on sump front right corner can be unbolted

These are the relevant diagrams for the castings the oil pipes connect to, there has to be something disconnected:
https://parts.jaguarlandroverclassic.../brand/jaguar/


Don't be downhearted, it is not that hard to remove the sump and sandwich plate, and I am sure your mistake will be obvious.

 

#4 and 10 are mounted as shown. Gaskets #6 and 12 were installed and new O rings #5 and 11 were fitted. The oil pickup pipe was also installed using a new O ring.
I will drop the rubber line from the cooler to the right hand side of the sandwich plate to see if any thing is amiss. Will keep you all informed.