Oily Spark Plug

Ian, You could have worn or stuck rings and aloowing oil past.

Martin P

What plug is it? ttfn Roland

I assume that should have read D16. As you say normal but highly susceptible to oiling in my experience. I'd expect an old 8COM or an new NGK A6 to perform far better. Silly question I'm sure but the oil level is correct? ttfn Roland

Dear All,

Just taken off the cylinder head. The copper/asbestos gasket looks like it's damage could this be the source of the problem? I did run my finger inside the combustion chamber and could swear I could feel very fine pieces of metal - part of a piton ring? There is clearly a leak somewhere as I ran the engine for 3 hours today and oil was seeping out of the head/crankcase join. The head of the piston is covered in oil.

Blue smoke burning oil, rings, head gasket, valve seals.

white smoke burning water, get this with cracked wet liners. ( Expensive on XJ6)

Lionel

Any suspicion of broken rings means a strip down to check. Could be just small bits of the gasket you are feeling. Blowing gasket could be the cause of you trouble. Just an observation FWIW.

Lionel

Martin P

>

And bloody suicidal radiator cap for the inexperience after overheating.

Lionel

Remote diagnosis is notoriously difficult! but in the spirit of helpfulness here are my thoughts. Ds are absolutely reliable and a broken ring would be most unusual (but not impossible) unless it had been broken on assembly or a partial seizure had happened. The inside of the combustion chamber is not machined so will feel roughish. Also small bits of very hard carbon can feel jagged and metallic. If the gasket is leaking then compression and therefore combustion temps/pressures will be reduced enough to cause plug oiling. If there is

3/10 of the cube root of bugger-all compression (i.e. virtually no resistance to cranking) then if it were mine I'd pull the crank and check the rings/piston and their fit in the bore. If its all OK then reassemble with new head gasket. IIRC this all started when you pulled the head to regrind the valves so it could (also) be that the head is not seating correctly. I'd pull all the studs and carefully use a countersink or larger drill to remove (by hand is best) the pulled up "fraze" around each stud hole in the block. That's good practice anytime you pull a head. I also continue to use a practice taught me by an old time mechanic named Norman (God rest his soul) and after thoroughly cleaning a re-used gasket lightly grease it to ensure a smooth and even torque down HTH and best of luck Roland

I would back up Roland and also add that when wife not looking soak gasket in hot oven to relieve stress and soften copper.

Martin P

helpfulness

Hello Ian,

To be logical - Before grinding in the valves there was less compression I take it, especially as you commented that it now starts more easily?

Increased compression on the compression stroke also means increased depression in the cylinder during the inlet stroke, naturally. This can draw oil up past the piston rings if they are ancient - like fifty years old! - and have lost their ability to seal effectively - or broken, of course, but I'd think that much less likely as D's are very reliable and understressed.

It was OK for a while, but then started to leak oil and smoke?

I'm intrigued that it only smokes now and again. From what you say, I'm inclined to think that - being an overhead valve engine - that there might oil running down a valve guide. They are only sketchily lubricated at the best of time by hot oily fog pumping in and out from the crankcase, so the occasional build up of oil around (probably) the inlet valve might account for the occasionally oily plug and the smoking.

First off, I'd clean the head gasket faces by hand, finish off by swabbing with a cloth soaked in meths and coat with a VERY THIN layer of silicone gasket stuff and allow it to dry for 24 hours. You will then have a rubber faced gasket which just might seal again, but it might not too! Clean the cylinder face and the head face with equal care, making sure there is a dry surface by swabbing that with meths too.

Roland's idea of re counter sinking the stud holes is a useful thought, and one I'd not considered.............. Don't forget to pull the head nuts down diagonally and a bit at a time when finally tightening them.

Really, copper asbestos head gaskets are not designed to be used twice and it might prove so difficult to reseal with the one you have that buying a solid copper gasket out of SE magazine (about seven quid, I believe) will be your only choice. But it's worth trying my way first 'cos it's cheaper!

Finally, did you top up/change the oil and what did you use if you did? If you used modern car engine oil, it is much lighter than the monograde oil normally found in a D and may well be flinging copious quantities up the bore that the scraper ring can't deal with and the oily fog in the rocker box is oilier - which is where I came in ;o)).

That should keep you busy for a while...............

Regards,

Kim Siddorn

Dear All,

Many thanks for all your advice. I decided to bite the bullet and remove the flywheel and crankcase this morning at 6.45am, very strange but it got the better of me!

I extracted the piston, the rings look ok to me. I have ordered new ones to be on the safe side and a new gasket from David Harris. I did try to persuade my wife to cook the old gasket but she gave me one of her looks, which I know from experience means NO, definitely NO! I should have taken Martin's advice and cooked it when she wasn't looking.

I will remove the studs on the head and get rid of the "fraze" which can clearly be seen. I will use a little bit of grease before I put the gasket back.

As for Kim's suggestion, yes I did top up the oil and this did coincide with the problems so this could be the source of the problem. I used standard 4-stroke oil used for garden machinery which is thin and could get into the valves. Come to think of it the valves did look wet to me so the oil could be getting in through the inlet valve via the push rods - an interesting thought.

What oil do you recommend please?

Regards, Ian.

This is getting complicated :-) Opinions differ on oils and this topic has been the subject of much heated, and largely uninformed, debate on the Atis list. FWIW my own view is that a straight SAE30 or HD30 should be fine for winter use. Side clearance of the rings is probably more important as much more than, say 2thou turns, the piston into a damn fine oil pump:-) Now back to Speed Machines Roland

understressed.

Dear All,

Many thanks for all your advice. I decided to bite the bullet and remove the flywheel and crankcase this morning at 6.45am, very strange but it got the better of me!

I extracted the piston, the rings look ok to me. I have ordered new ones to be on the safe side and a new gasket from David Harris. I did try to persuade my wife to cook the old gasket but she gave me one of her looks, which I know from experience means NO, definitely NO! I should have taken Martin's advice and cooked it when she wasn't looking.

I will remove the studs on the head and get rid of the "fraze" which can clearly be seen. I will use a little bit of grease before I put the gasket back.

As for Kim's suggestion, yes I did top up the oil and this did coincide with the problems so this could be the source of the problem. I used standard 4-stroke oil used for garden machinery which is thin and could get into the valves. Come to think of it the valves did look wet to me so the oil could be getting in through the inlet valve via the push rods - an interesting thought.

What oil do you recommend please?

Regards, Ian.

Lister D oil...? Every D type I have ever got has had any black goo the farmer could find in the sump and seem to have suffered very little distress as a consequence. I would recommend a decent quality straight non-detergent oil, as Roland says straight 30 would be fine. I also use Duckhams multigrade (in the blue and yellow tins - can't remember the grade) with no problems.

Regards

Dan

Gentlemen,

Reading all this stuff and giving my own opinion has caused me to think on about a problem I have with my Bradford which by the end of the season was pumping oil out of every orifice it has including both inlet, exhaust and the silencer. So maybe I shall take you and me into the garage for a good look, anybody got a head gasket for mine.

Martin P

understressed.

Oil grade? Look in the Lister manual for confirmation, but I think Roland's right in suggesting a straight monograde SAE30 - 40 in the summer if you are being picky, but I doubt if it'll care. They are so understressed that bacon fat will do!

I feel I ought to make the point that stationary engines are massively over engineered. They have a pitifully small output, very low compression (to the extent that if things DO wear out, it is sometimes insufficient to fire the mixture!), broad bearing surfaces and really are built to last. Many of them have seen little or light service and it is quite unusual to find a worn out stationary engine, to the extent that it is worthy of comment.

Having spent much of my adult life working with bike engines, I still find it hard to believe the extent to which our oily toys represent an internal combustion backwater where the physical weight of an engine seemed to indicate an ability to soldier on despite the worst efforts of the owner.

Fitting new rings in the current bore will - I'm afraid - probably make matters worse.

Firstly, the bore is nice and shiny and that shiny surface is called "glazed" as the surface of the bore has been compacted and polished smooth by the action of the piston. The current rings will have "grown up" with the bore and - if not damaged and free to rotate in their grooves - will form a good seal. You might like to remove the top one and check its gap in the bottom of the bore. If you are intent on fitting new rings or the ring gap is too big, then make sure you get the bore honed before fitting the rings.

Secondly, if the engine has seen much service, there will be a wear ridge at the top of the bore. Your nice, new rings will have a sharp edge on the top ring and will probably break the first time it hits it! This ridge will be removed or smoothed by honing.

Heat soaking your copper/asbestos gasket would not (in my opinion - sorry Martin!) do any good. You would need to heat it to red heat and drop it in cold water to anneal it and this will promptly remove most of the asbestos, thus scrapping the gasket! Fit your new solid one with confidence.

Regards,

Kim Siddorn

I'd rather have a free bottle in front of me than a free frontal lobotomy!

Ian Goodwin said