Using oil - Advice please?

[malcolm]

My car (series 2 4.2) is running beautifully. Ticks over sweetly, starts well, runs well and gives me 23mpg overall on a decent run. Oil pressure 50'ish+ running, and ticks over at 40 or just below if really hot. BUT, I use a pint of oil about every 260 miles. It has always been a bit oil thirsty, but is maybe getting a bit worse. Due to other work being done, the bore and rings were recently inspected, and declared to be perfect. Main and big end bearings were changed at this time as the engine was out so "might as well". There are no major oil leaks, just the normal dribbles here and there.
No obvious smoke, although some if I really boot it to high revs. And it does spit out some black stuff when you first start it.
Obviously, the oil must be going somewhere, and if it's not the bore or leaks, I suspect it can only be a problem with the cylinder head. Question is, what fault with the head is most likely to lead to high oil consumption?
Your help would be most appreciated.

[politeperson]

Have you checked your engine breather isn't blocked? See what is coming through the pipe to the inlet manifold, assuming you dont have a catch tank.

Picture of your engine bay would help.

Have you checked your spark plugs to see if one or more is oily? This could point you in the direction of one or more cylinders.

Is your sump overfilled?

Is your dipstick an e dipstick?

Is your engine oil too thin a grade?

Worn valve guides? You can add stem seals to reduce oil consumption.

Just a few thoughts.

[malcolm]

Thanks James. Most of the items you list are ok; sump not too full, proper "E" dipstick, engine breather free, castrol classic 20/50 used etc.
The plugs do oil up a bit.
I suspect you might be right when you refer to valve guides - other thoughts?

[malcolm]

Sorry, as requested, I've added 2 pics of the engine bay:

[rfs1957]

Hi Malcolm,

Sounds a bit like mine ............. think it was 9 litres in 5.500km on the Scotland round trip.

Is that 16 pints for 3.500 miles ? So 220 miles per pint ?

Worse than yours !

Some will tell you that this is not abnormal, and it wouldn't bother me that much per se were it not for the fact that our cream cars go beige/brown all around the number-plate and bumper area, and cars of whatever colour smell when they use that much oil.

It's interesting that we're still way below the oil-consumption allowed in F1, where oil is clearly being exploited as a secondary carburant !

https://www.motorsport.com/f1/news/tech ... pa-946864/

Even the lower 2018 objective is still 63 miles per pint !

Maybe burning oil was what got Jaguar the quoted 265 bhp for the E-Type ....................

However, in the discussions I had over the last few months with Mike Wilkinson at

http://www.mandcwilkinson.com/

and Andrew Barker at

https://www.chesmanengineering.co.uk/

they were both adamant that there was no reason to live with this, and that valve-guide seals were the answer - being fitted only on the inlet side, as the exhausts need the oil, and anyway the principal 'suck' comes on the inlet side.

Like you I believe my block and rings are OK, because they've not done that many miles since VSE did the bottom end for the PO, but the head was definitely not touched, and has various other issues, which is why it will be the object of all the work over the winter.

It's easy enough to find out whether your breather is responsible, but I have never personally had any luck solving an oil-consumption problem on an engine, ever, of whatever sort, through attention to breathers - the root cause has always been a mechanical wear one.

I do nevertheless hope yours is something simple.

[malcolm]

Thanks Rory - I think you're probably right re the mechanical failure, and about valve guides being the culprit. Are valve seals better than just replacing the guides with new ones? Excuse my ignorance, but earlier posts will have demonstrated my lack of engineering proficiency!

[rfs1957]

No shame in asking, and I have no shame either, as my experience in other sorts of motors would not qualify me to expound on an XK.

Which is why I saw Wilkinson and Chesman.

Fitting just the guides without the seals is only doing half the job.

[christopher storey]

260 mpp is not that bad, and very close to the consumption they gave when new. If it is valve guides which are worn, the tell tale sign is a blue puff on every upward gearchange, and if really bad , continuous smoking on the overrun. The XK engines of this era did not have seals : IIRC they only came with the S3 XJ6 , and to retrofit them requires a change of the guides for the pattern used on the late XJ6 . In my view this sort of work is really only justified when you reach perhaps 100 mpp or are doing a major overhaul for other reasons

[E600]

I hope I am stating the obvious for everyone's benefit. Inlet stems seals can be changed in situ. Clearly valve guides require the head removing.

Perhaps try the seals first. It is possible to fit other marque seals ask at an old fashioned machine shop, or Chesmans might provide the answer.
Best of luck
Pat

[PeterCrespin]

On the same "hope this is obvious" tack:

If the engine already has inlet valve seals and hardware to match, they can just be replaced. But if the engine did not have seals, the later seal-compatible spring seats, retainers. collets and valve guides are all needed to prevent the seal being mashed and pumping oil down the stems.

[malcolm]

Thanks for all the advice. I don't normally get smoke. I was followed through Europe by another E, and apparently the only time he saw smoke was in an emergency when I had to floor it (red line) in first to avoid being sandwiched by a lorry in a city centre. I don't know if it has seals fitted. From the comments, I think I'll just press on until it gets worse, then have someone decent at the job take the lid off. Would some one be able to see if seals (and thus the associated gear mentioned by Peter) are fitted without taking the head completely off? Just by taking the cam covers off and working in situ?

[chrisfell]

Malcolm,
My engine uses a little oil. On startup it blows some blue smoke, and on the overrun a little blue haze puffs out. (Apparently, these are both symptoms of valve guide wear, the former when oil drips into the exhaust port after the engine has turned off, the latter when oil is sucked past the valve guides when there is negative pressure in the inlet manifold.) My engine probably looses more through leakage than it burns, but overall I add the remains of 10 litres bought for the oil change over the following 3,000 miles. The amount of oil lost isn't as important as any change in the amount that is being burned/lost. Mine hasn't changed in over 50,000 miles. It leaks, leaving oily streaks everywhere. I clean those up. It burns oil making blue smoke. I dont care, its an old car, plenty old enough to smoke. I'll not start to chase worn compenents or various leaks for some while, or until something breaks.

As to your last post, what colour was the smoke when you floored the accelerator? If is was black, dont worry. That's the XK engine trying to deal with a sudden WOT. If it was blue, again dont worry just yet. Blue smoke under acceleration is caused by (a) worn rings or (b) a blocked breather. Check the gauze breather, take it out and clean it thoroughly. If the blue smoke is still apparent, rings and bores may need attention. If not, problem solved, the car burns a little oil but is ready to be driven.