First a little history. This car was purchased by my father for my mother in 1981 when I was in college. I was always taken by it's beautiful lines and sable color ( it is VP), and of course being my mothers car it as well as her of course have always held a special place in my heart Maintenance at the dealer had been meticulous from purchase to 2001 when they sold it to me for $2k as my "go to dinner in car". The avatar pic is from 2008 when here in central Florida we actually had a heavy frost- weird!!

From 2001 to 2013 it has accumulated maybe 10,000 miles- not nearly enough regular usage. So over those 12 years it got worked over intermittently for problems as they surfaced, and oil changes performed ever couple years just because. The local import shop did new calipers/rotors up front, shocks all round, rear brake work, fuel pump, fan clutch and finally new tires after 10 years. It got new plugs twice, but the last time I tried one plug had become frozen in the head so I only changed the other 5...ugh Yesterday she got wipers and new horns- whoo hoo!

Anyways, it is being pressed into fairly regular service as I recently gifted it to a dear friend (yea, I know, double edged sword gift...) who is in financial tough times. Though I have told her that I will take care of maintenance bills, within reason.

So, with it being in regular service now it has become apparent that it burns quite a bit of oil- maybe a quart every 2 weeks or 300-400 miles( not sure on this distance) But certainly way too much oil consumption. It does not smoke excessively or obviously, but when revving the engine parked and looking for smoke in the angle right light I can tell it is indeed burning. Exhaust tips black but this may be normal soot. It does seem to run fairly rich also. There minor oil dripping in the drive way, though the underside of the engine is fairy oily from drippage that blows back at speed. So there may be a leak at the bottom front area?

My thinking is 1) rings on one or more cylinders have gone bad- worm or stuck? The engine runs about as always with fair to good power production (especially after the frozen fan clutch was replaced), little hesitation, idles nice and no funny sounds ( after the roaring fan was fixed LOL)
2) the oil seepage at the front of the engine really is enough to cause this much oil loss. I have no clue as to what on the front-bottom area of the engine may be the site of the leak, but probably need to de-grease it take a look on the first run after.

What I am most concerned about obviously is ring problems, as I'm sure an engine removal and ring job would well exceed the value of the car, and re-powering it would cost even more. Thus basically she may be heading to the junk yard, which not only breaks my heart and will put my friend ( ok, unofficial and potential fiance ) in a tougher position. A compression test on cyl #4 would as a minimum require heli-coiling, and that even is something I wouldn't be comfortable doing... the thought of threads and metal shavings falling down into the cylinder freaks be right out! So it's is off to the shop sometime soon I guess for a evaluation- they do know me well at least.

Sorry for the rambling long winded post, but this is where I am with my/her Jag. Any enlightenment is welcome and very much appreciated

 

I think that car has a lot more life left. Are you using 20/50 oil, or is cold weather an issue. Sounds like it is suffering from "little old lady from Pasadena" syndrome.

An over rich fueling issue can wash lube off the bores and accelerate ring and wall wear.

Two to three quarts every thousand is a bit much, but not beyond reason. It may stabilize at one quart low on the dip stick.

Of course, the leak is another issue, but, not unknown in British cars. Just rust prevention!!!

Iron to alloy bond corrosion is hard to bust without major damage. But, well worth trying by regular pooling of penetrants in the plug well. Then, moderate force, tighten a bit then reverse, if you can get it to move just a tad, follow with a lot more penetrant and allow it to seep in. Back and forth just might bust it loose with no injury to the threads in the alloy head. I hope you used an antiseize when you changed the other five!!

Then, if that cylinder just isn't firing and the spark plug has to go, bust it loose and repair the threads with a heliccoil or similar thread repair. If you set the offending cylinder at TDC and then after removal use a strong shop vac, you can clean it out quite well. An impact wrench can move things when just torque will not. Torque plus impact is powerful. With a huge amount of luck, the plug will come out and the threads remain pristine.

Back to oil consumption. A nice long ride at freeway speeds can do a lot. The fabled "Italian tuneup" has worked, but there are risks to an older engine. WAs there decades ago in my 47 Ford. Spun the bearings. Oh well, I was looking to a much "hotter' engine.

Carl

 

Thanks Carl-Yes, 20/50 wt oil. And LOL cold is never an issue in Florida, though she is a bit slow to turn over in the winter, so I figured 20/50 best. FWIW the oil on the stick is excessively black considering how few miles it gets on it, plus the addition of new oil. So yes either fuel contamination and/or metal ( bearing or rings or cylinder- ugh) wear or both is what I'm afraid of. I might consider getting an oil analysis test done?

When I changed the plugs the first time there was a bit of aluminum left on the old plug, so I did use antiseize on the next set. When I went to change them again that one plug was not going to come out even after the aforementioned soaking and back and forth, so I just left it knowing next time would be thread repair time. Ugh.

Funny you mention the Italian tune up. The more she is driven the better she runs for sure, with the exception of oil consumption.

 

From the day it came out in 1948, the XK engine was always heavy on oil, and mileages of 200 miles per pint were commonplace until finally, in the 60s, inlet valve oil seals were introduced and cured the problem.

In your case with a 100k miles car, it is likely these seals have gone a bit hard, especially with the lack of use. In addition, you say you have a leak at the front of the engine, and this, really, can only be the oil seal on the end of the crank. This can be replaced without a stripdown, but the sump has to come off, so not an easy job. There will always be seepage from the rear seal, as this is a rope-type of pre-war design. Mine always leaked and stained my driveway.
There is, (or used to be), a modification available to use a modern split lip-type seal, but the crank has to come out so the scroll where the old seal sits can be machined off.

If you can't get the plug out, try when the engine is hot, as aluminium expands more than steel so may have less 'grip' on the plug. If you can't get it out, you might have to take the head off. This could cause you to enter a sea of troubles with corroded headstuds and a seized-on head, so is not something to undertake lightly unless you're doing some serious overhaul work.

Of course as others say, there could be wear in the bores, but you'll only know if you take the head off and look.

Worth making sure, too, that you use an oil suitable for the car. (20W50, or 15W40). These modern "paraffin" thickness oils like 5W30 will find their way out of an old engine design like this.
Also clean out the engine breather at the front of the engine. Look for a black rubber "dome" top-front, with a steel tube going back to the inlet manifold. Inside that dome you'll find a steel gauze filter and it's likely blocked and not letting the engine breath, thus forcing oil out where you don't want it to.

 

When removing plugs you might try this: loosen it a little and soak the thread area with something like PB Blaster or Aerokroil. Hopefully it will get down in the threads and help things come out.
I remember reading that we should not try to remove plugs from a hot head; I don't know: it makes sense that the warm head would be expanded but I am scared to try it. When I removed the plugs from the aluminum heads on a 420SEL several years ago, they were tight, and the above spray-lube strategy was used; I got them out without damage.
As for the oil consumption: check the crankcase ventilation system; if it clogs and pressures up the crankcase it will blow oil out.

 

Hey NoClutch, I also live in Central Florida. Melbourne to be exact. If you are not too far from me, I will be willing to help you out in diagnosing the problems you are having. Just hit me up with a PM. After you clean the underside of the engine, take a look at the rubber hose at the rear of the oil filter housing, it is about 3" long.They tend to leak when you are driving and hardly ever noticeable at idle speed.

 

If the cost is the difference. buy a case and use it as needed.

 

Hey Noclutch, I don't think you case of oil burning is an isolated one. My 75 (series 2) Daimler Sovereign goes through 2 Litres of oil (about 4 pints) if I take the car on a highway trip non-stop 280km. (174mi.). But If I drive it around town it doesn't burn a drop.

When I bought the car it was badly out of tune and had 10w30 grade Castrol GTX in it, totally fouled with gasoline and oil pressure was barley 30lb/ft.
I prefer the car to run on mineral oil like the engine would have when it was new so I always put in Penrite HRP 40 oil (25w70) Achieves great oil pressure 80lb/ft under load and between 40-50-lb/ft at rest. That is considering my engine is untouched and was sitting for many years with the previous owners also. The cars done 58'000mi. Never been around the clock.

But i suspect my oil burning issue arises when the motor is hot enough for there to be a good enough tolerances to allow oil to be seeping past something, be it rings or valve seals. Damage has been done somewhere.
Still she lives in a much colder climate than sunny Florida!! All the way down here in New Zealand. Still not as cold as my winters spent living in NY!

 

Interesting. Removing spark plugs from an alloy head. Best hot or cold? Using tne expansion differential as a guide? My question is does the alloy expand away from the iron plug or toward it? And, is the alloy softer when hot and as such be at risk for stripping?

Decades ago, I helped my daughter's then boyfriend remove the four plugs from her VW beetle. Ugh, what a mess we made! Each came out with a chunk of head. Next mess, trying to drill the holes straight with the engine in situ for helicoils. Disaester.

So, we removed the engine. Not bad in a VW. Pulled off the heads. Amazingly, a new pair did not cost an arm and a leg. Got it together with a copious application on the threads of the new plugs. It ended well, but a huge exercise for a seemingly simple task. That and a previous adventure with a stripped thread in a head of one of my Corvairs soured me on alloy heads. Oddly, my old V8's with alloy heads never had such an issue. probably, because they never ran long enough between rebuilds to seize!!! Lots of lead in the sole of my left shoe when I was younger!!! Addicted to the push and sound of a hot V8 on twin Smitty's wound out in second gear!!!

Although getting access to the plug on Jaguar is no picnic, it is doable with lots of a good penetrant. Agree, if the cylinder is on TDC, a good shop vac will evacuate any swarf. and if drilled, using heavy grease on the bit will gather the most of it anyway.

Or let the machinist do it. Not a daunting task to them atall.

Two quarts per 1000 isn't bad enough to give the car to the crusher. Way back when, I had a beat up A Ford that ate it much faster, only ran on two and at times three, but it beat walking!! It got a B engine and went junk class racing!!

Carl