Engine: 1964 3,4L. Overhauled in 1999 and driven approx. 40 000km since. Compression figures lays around 10,8 bar except no 5 which has 10,1bar.
Oilconsumption 3L/1000km or 1L on each tankfilling. Oil quality used is Castrol 20/50. No oil leaks from engine.
Recordings:
Sparking plugs appearance light burned, no oily or black.There are no light blue exhaust only the lightgrey. When passing RPM 3000 the exhaust changes to dark grey colour. When I put a white cardboard close to the outlet exhaust pipes, there are much more oildrops coming from the pipe from cyl. 4, 5 and 6 than the other 3cyl.
My thoughts are turning over to oil leaks out through the exhaust valve stem and into the exhaust pipes wihtout beeing in contact with the combustian chambers.
Do some of you have the same experiance? Please be my guest and any answeres are appriciated.

 

just a wild guess... but the head, i suppose, could be cracked in such a way that it could happen as you suggest, i guess. so either pull the head or maybe the 4,5,6 exhaust manifold and have a look-see.

 

Did you replace the inlet valve guide oil seals ? There are no seals on the exhaust valve guides, because there is no vacuum there to suck any oil into the exhaust manifold. I suppose you are aware these engines were never light on oil being quite thirsty for oil and it was once normal to out a pint in every fuel tank fill. This was gradually sorted out over the years. !litre per tank fill does seem excessive, I have to say !
Any oil dripping badly at front or rear of the engine ? The cranksaft rear main seal is known for leaks but the front seal can also leak a lot out.

 

As Fraser says the early 3.4 engines were quite thirsty on oil.
I remember a road test by one of the better English Auto. magazines confirming a consumption of 1300 miles to the gallon of oil which matched the factory figures.
I drove MK7 3.4 litre cars for 15 years (1964 to1979) and that sort of oil consumption was quite normal.
Extrapolating from your figures of 3 litres/1000 ks then 4.5 litres (1gallon) would be about 1500 ks. which is roughly 900 miles.
So, you are not that far off factory expectations.
I can suggest that where you are coming from is comparing it to modern cars which seldom need an oil top up between oil changes.

As a footnote I remember visiting the local Jag. dealer around 1965 and seeing the brand-new cars emit a puff of oil smoke at startup.
Even the best inlet valve seals will leak when under an oil flooded system as occurs in an XK engines head.

 

Stop using 20W-50. It is rubbish with cheap VI improvers and shears out of grade to an approx SAE 30 in no time. It was designed for Sir Alex Issigonis Minis to the Landcrab (Austin 1800) with combined gearbox/engine sump ~ never an XK engine. Use a synthetic 10W-40 or similar (remember it is an SAE 40 at operating temperature & not too thin as many claim). Jaguar never recommended anything higher than an SAE 40 in torrid or tropical conditions as I have written about frequently here. Should you use a little more oil initially it is the detergent package cleaning up your ringbelt area. If the engine was pampered in it's run in/break in period you might have an oil burner for life due to cylinder bore glazing or polishing. (two different mechanisms). If this has occurred the only answer is to dismantle the engine, fit new rings & re-hone as pictured below.

Jaguar's run in/break in procedure is not appropriate with modern lubricants. Listen to Fraser re: "Did you replace the inlet valve guide oil seals" But I would expect some blue smoke out of the exhaust after running against compression & then flooring the throttle.

See: https://www.jaguarforums.com/forum/m...engine-263052/

 

The 3.8 engine was initially probably the worst oil consumer. "In September 1962, the 3.8-litre engine’s reputation for burning oil was tackled with new piston scraper rings".
Source ~ many scribes on the subject plus Technical Bulletin.

 

Alfa Romeo twin cam engines of this era had zero guide seals by design. It was a case of fill up the oil & top off the tank. I went through 7 oil guzzlers.

 

the consumption is definitely to high. Anything over 1.5 liter/1000 km is too much even if these engine need to and do use quite some oil. My MK2 3,8 is between 0,8 and 1,2/1000km
as you do not see blue smoke it seems that is is leaving the engine via a differnent place. Exhaust valves are unlikely as there is no vacuum present. They need to be massive worn to let oil through
Your sure there is no extreme leakage via the crankcase ventilation?
20W50 is fine for the engine, a SAE30 will be too thin when hot - tried that and switched back after a short period.
Have you used an additiv like Lucas HD Oil stabilizer - this may "thicken" the oil ab bit, reducing consuption from wear.
Best
Peter

 

Hello all and thanks a lot for your comments.
As I stated. There are no light blue smoke in exhaust. To me it means no burning of oil.
Analyse of exhaust by placing a white cardboard close to the outlet pipes, shows very oily black stuff on the right outlet. Much lesser on the left pipe.
Sparking plugs are showing as the workshop manual states "normal condition". Clean burned and no fatty black stuff.
No oil leaks from the engine.
Normal oil consumption is about 1 litre pr. 1000km acc. to workshop manual.
The engine was overhauled back in 1999. I have the receipt with details, nothing is stated regarding the valve liners. It was an approved workshop who did the work.

Since there are no light blue exhaust, my thoughts start playing as follows: Can oil fill in through the exhaust valve stem when the valve is closed? As soon as the valve opens, oil collected in the exhaust chamber (outside the the valve), will be blown into the exhaust pipes without being burnt. May be this is foulish thoughts by an amateur. During next year i will have to remove the head and have it analyzed.
Looking forward to your comments

 

Not So. Then your engine is worn or suffering from bore polishing or glazing. Some oil consumption never did any harm.

BTW I'm a Tribologist that worked for a Supermajor oilco for my entire career. And don't put any additives (mouse milk) into your oil. Most are just VI improver & make the oil as thick as hell & ruins a properly balanced lubricant formulation. Any modern manufacturer would immediately void your warranty the minute they analysed the oil and found additive addition.

Jaguar's original viscosity recommendations for the XK engine. These engines are not designed to run on treacle. i.e. 20W - 50. It takes too long to circulate around the engine leading to wear at every cold start. Are you sure you don't have a leak? Rear Asbestos rope crankshaft seal being the most common. As Bill comments your consumption is not outside norms for the 3.4 XK engine.

BTW Price's is BP today. The others are obvious.

 

Hi Peter, thanks a lot.
The crank case ventilation filter is clean. No external leaks. Very oilrich exhaust cyl. 4,5,6. Thats why I think of the possibility of oil leaking into the exhaust chamber via worn valve guids.
About the Lucas HD Oil stabilizer, no I have not tried something like that. I will pull off the head during the winter/spring season and see what findings I can discover.

 

You have to be kidding that you would pull the head on a properly functioning 3.4 engine with a slightly higher oil consumption.
Get real!!
This is a 60+ year old engine and as I have previously stated and backed up by Glyn's remarks that sort of oil consumption is NORMAL for these cars.
At the same time, I have two family cars that never need oil top up between changes. ( Ford Falcon utility and Mitsubishi Colt)

If you want to waste lots of money on new cylinder head VRS kit then go ahead. but how many litres of oil could be purchased for the cost of the kit?
I understand you need to hunker down in winter but doing what you propose to do is a WOFTAM (waste of flaming time and money)

 

I sometimes check the level in my X type and XKR, but I've never topped them up. I've added oil to my Daimler a couple of times, but that may be as much due to uncertainty in measurement from the dipstick as oil consumption. For my 3.4 Mk2, however, it's different. When it was my daily driver, I checked it once a week and probably added a little each time. For driving it across Europe or after long distances, I'd top it every morning. I always carried a can of oil in the car, except when I worked in a 'bonded area', where it wasn't allowed (and that was very difficult for me to adapt to). I wouldn't worry so long as the consumption is better than 100miles to the pint. I'd also consider an 'Italian tune up' as our cars were intended to be driven hard, rather than treated with kid gloves.

For oil, I'm not an expert and would follow Glyn's advice. Personally, I favour a 10/** (where ** = anything above 20) synthetic and would avoid most modern multigrade mineral oils as I suspect the manufacturers save on additives but still produce something that'll not poison catalysts. When Jaguar listed 20/50 oils, I'd guess it was because that's what most early multigrades were and they probably expected them to degrade to a 10/30 within a few hundred miles.

I don't see the point of seals on exhaust valve stems as there's no great vacuum to suck in oil. As original, Mk2s don't have seals on the inlets either and should produce a healthy amount of upper cylinder lubrication smoke when you lift off the throttle at speed.

Burning a little oil is part of the fun!

 

Note: Regent/Caltex/Texaco comment from the S Type Service Manual regarding Havoline SAE 10W-30*. With the 20W-40 they are sticking strictly to Jaguar recommendation (Nothing above an SAE 40).








I don't open my modern Mercedes Benz hood/bonnet between 15,000 Km services.

 

How polite & considerate ~ LOL ~ we all know what the "F" stands for