I am having a new issue on my low mileage (52K) XJ8 and a search of this forum provides surprisingly few results on this topic. The issue is that I am seeing blue smoke when starting the car after it has been parked for a while (say a week). After driving it for a couple of miles, the smoke disappears and it runs clear after that.

If I start it after being stood for a day or 3 there is no smoke. All of this suggests (to me at least) a very slow oil leak into the cylinders from somewhere while the engine isn't running. Anyone here have any ideas what might be going on?

 

Is there oil in the air filter housing or around the spark plugs?

 

Mine does the same. I have barely any oil consumption. No blue smoke when either heavy on or off the accelerator... So all is ok.

 

I guess our definitions of "all is OK" are different!

 

Usually when you have worn valve guides this happens as oil makes it thru to the combustion chamber.
However at your low mileage this is a little unusual.

If this is the cause you are likely to have carbon build up on the upper sides of the valves as well. More than normal.

 

But wouldn't that cause blue smoke most of the time, not just on startup after being parked for a while?.

 

If the wear was "bad" on the valve seals/guides you would get blue smoke all the time.

If the wear is not that bad and even on only 1 or 2 valve seals/guides once its warmed up enough it would likely stop.

However at only 56k I think its unusual to have warn valve guides/seals.

Also a non-functioning PCV valve could cause blue smoke so check yours but I would think you would get an error code.

I dont know of any other way oil gets into the combustion chamber unless your piston rings are worn badly causing blow by. If you have blow by
your oil gets dirty quickly.

Maybe someone else can chime in.

 

As written, my rather low mileage 3.2l (currently just passed the 100k mi) does the same. But not always. If I for example really drive it hard and then let it stand over night, it will chuck out a blue cloud, not thick. I blame that on the crank case ventilation system on the A bank, fill Ing the intake with oil mist/steam and that being sucked it upon first start... No blue smoke other than then. So there is no issue...

 

First and foremost....your 'symptoms' depict worn valve seals which is not uncommon on these cars as most of them lead sheltered lives and too many short stop start runs, all odf which is not good and causes the seals to harden with age.

These symptoms show up after a long run with engine fully heated and then shut down allowing the hot oil to dribble through the seals and into the combustion chambers on the back of the inlet valves at next start up.
My car exhibits this trait.

This opposed to worn valve stems and guides which will give you smoke on the over run.
This is not a common feature of these engines.

The other thing to look at only if you have increasing oil consumption is worn cylinders and rings in combination with worn guides and stems will give you are blue haze under hard acceleration and a long overrun.

A small puff at start up for a minute or two is nothing to worry about.;o)
If it does concern you, try the application of a bottle of seal reviver fluid
which, if the seals are not too hard will soften them up a bit reducing the effect.

Regular oil changes at 7,000 mls with top quality high ZDDP oils will also reduce the problem and try to stay away from short haul trips where the engine doesn't really get to proper temperature. ;o))
My car has been in my ownership 10 years this year and has covered 214,000 klm (133,000 mls) with negligible oil consumption on an original
Nikasil engine. ;o))

 

Thanks Xjay8 - the valve seal issue points to age-related deterioration rather than mileage related wear, which makes total sense in my case. I'll try the additive approach first and see how that goes.

 

It certainly can't hurt to give it a couple of doses and a good long flogging ;o))
Cats love to stretch their legs and do what they were designed to do ;o))

 

Maybe, also, a heavier oil 5w40?

 

I had the same issue w/ a Diamante years ago, I added Lucas oil treatment/stabilizer & never seen smoke again.

 

For an X308 5W40 is the factory recommended grade for most conditions.
Perhaps you meant 10W40-50 as an alternative?
I use 5W40 Penrite HPR-5 during the Winter months and up it to 10W50
Penrite HPR-10 for summer months.

 

Great thread . I have just bought a 2002 32k mile XJ8 3.2 import from Japan which is quite astonishing because of the lack of any rust whatsoever. However.... on a three hundred mile trip this weekend where I pushed it slowly up to quite high speeds I am aghast to see how the oil level dropped when I checked it this morning. There was no evidence of any smoke from the back or perhaps I wasn't paying enough attention to that . It's great to get a low mileage example where everything is so tight and smooth but I am wondering if the valve seals have hardened through such little running over the years. I have a 60k mile one that burns no oil whatsoever. I will try the additive and fingers crossed I haven't screwed it completely !! The lesson learned....Must pay more attention to oil levels in future mid journey.

 

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Valve seals will show blue smoke as you let of the gas (building manifold pressure sucks oil past the seals); if on acceleration it is worn rings. Likely your oil level drop is simply oil not yet draining into the sump. Keep an eye on it and let us know what occurs.

 

Don't use any of those oil additives like Motor Honey or the like. Your journals are quite small going up to the cams and can restrict flow.

 

Well it seems that the problem is an oil leak. I noticed it this morning . Nothing huge and a litre of oil got the level up to range which means it was leaking slowly over the 300 mile journey . The engine was making a kind of whooshing roar that could have been escaping pressure related last night at low revs that went at higher revs, I haven't had time to look properly. I am hoping it's a simple gasket. I think the issue with a 20 year old low mileage (32k) engine being used so little is that some of the gaskets and seals will probably pop when I increase the revs. Looking over the history it only covered on average 1500 m per year. I have been seduced by the totally mint bodywork and am praying I haven't got a huge wad of bills for blown gaskets coming. Any advice on how I should proceed ? I was always of the impression that it's best to start with great bodywork and then even if you need to work on an engine it's cheaper than fixing rot. Old cars are...... double edged.

 

You need to get it onto a lift and check for tracks from the leak. Rear seals, front seals, oil pan gaskets are the usual suspects, but as you note, in a car this old, with this few miles, lots of places where the gaskets and seals could have dried out over time. While on the lift, torque the pan bolts (on my last 01, they were loose); and maybe an oil change with 5W40 weight and a new filter. After living in Japan for five years in the '80s, I would suspect the car is absolutely like new -- a national love affair for luxury European cars, and incredible attention to details in the upkeep of all.