I was working on the Jag the other day and noticed some oil pooled on top of the engine when I was replacing the cap rotor plugs wires and injector hoses. Leaking oil is never good and I have a bad feeling that my engine may need to be rebuilt with new gaskets installed. Since rebuilding the engine is far beyond my budget, how difficult would it be to swap in a 6.0L from a newer Jag with the electronic ignition? Does the 6.0 use the same engine mounts as the 5.3?

 

I would be cheaper to install new gaskets etc than replacing the 5.3 with a 6.0. I bought a low mileage 6.0L engine and have had to rebuild it, all valves and guides needed to be replaced, head gasket was almost gone.

Also if yours is a pre-Marelli then ALL of the wiring loom, Marelli ECU would be needed and then the foot well where the Marelli ECU sits is different.

 

OK,

The engines are basically the same physically, but, many little ietms that will mess with your head.

The engine mounts are in the same place for both engines. The trans, 4 speed TH400, has a different style. Not rocket science, just different.

Engine management may not be too bad, as your 1991 is a Marelli system, as is the 6ltr.

In the V oil pooling on a 5.3 is either:

Distributor o/ring gone hard, normal.
Oil sender units, usually the idiot light small one, leak badly, normal. The larger unit, gauge, also do leak, not as common.
The paper gasket that is the seal for the plate at the bottom of the V can leak, but normally only a weeper, not a pooler.

Thats about it for oil in the V, and fixed in about 2 hours tops, including drinks.

 

Most of the pooling was towards the back of the engine behind the Bell crank for the throttle bodies. I did see some near the distributor cap so I'll swap out the O-ring while I have everything apart. Also for the 6.0 swap I was looking at one of the nippondenso distributorless engines, not the Marelli ones, so id be swapping the harnesses and ecu out anyways.

 

That late an engine would be first I reckon, so you will basically be writing the "how to".

The oil at the rear is the oil switches.

 

Could the oil at the top rear be the camshaft "half-moons"?

 

The EDIS V12 only came in the last of the saloons, I'm don't know where the ECU was located in these cars. The harness in the XJS runs down the RHS of the transmission tunnel and will require almost a total interior strip to replace it with the Denso harness.

If I were you I would fix the engine that's in there.

 

Always possible.

The fact the heads are angled slightly to the "outside" that oil leak, and they do leak, usually runs down to the side and off the oil pan ledge.

There are banjo bolts at the rear of each head, and unless disturbed rarely leak, MUCH CARE needed if you wish to go there, as the threads in the alloy tappet block WILL strip, and basically ruin your day. Access to them with the engine in the car is special, and by that I mean near impossible.

The banjo bolt and copper washers on the oil switch pedestal can leak, but again, rare.

The oil pipe that runs from the oil filter housing, up the LH side of the engine, and across to the RH head can fracture, but I have never seen that, only heard of it.

Oil light switch leakages, are as common as "Meat Pies and Holden cars" down here.