How much engine oil?

[MrWright]

I have a 1947 T35, and the engine leaks like a stuck-pig on each cylinder based and head.  I have replaced both gaskets on both sides several times and it still leaks.  The dip stick that came with the bike looks to be home-made, so I suspect that the level in the crank may be incorrect.  I have come to believe that I am over filling the crank case and causing the leaking issue.  Does anybody know the correct amount of oil for the crank?  The owner’s manual doesn’t specify amount, just level.  Thanks all in advance.  Picture attached for fun.

[MRD]

From the technical data in the Mk maintenance manual. The engine sump capacity is 4 pints (2.27 litres)    From may experience the dip stick does have a home made look to it.
Hope this helps
Regards           Martin

[Doug]

As Martin said, the factory dipstick does look homemade.



The slight bend above the tapered bung I added to move the handle further away from the cylinder; originally it was straight.

The oil level marks are at 1-5/16 and 3-3/8 inch from the bottom of the bung. The size of the bung will effect how low it sits in the taper hole of the crankcase, so for completeness I measured that at a diameter of 0.265 inches. The level marks are just cross chisel marks.



If you look closely you can see the level marks have been raised 1/4 inch and the originals nearly obliterated by peening. Problem is I can not now remember if I did this, or that is the way I got it from the late Graeme Brown's stock of ex-Kingswood spares.

-Doug

[MrWright]

Thanks Doug and Martin, you have answer two questions, the amount of oil and the origins of my dipstick, after review of your pictures, I have determined it is original.

[Doug]

As for leaks at the base of the cylinders, it sounds like the joint face is not flat. There is only a thin paper gasket used there, so the joint does need to be pretty good as the gasket is not going to make up for much in the way of imperfections. A thicker gasket is NOT recommended as that is a good way to fracture the mounting base of the cylinder when you torque down the retaining nuts.

Usually the cylinder base stay quite flat, but the same can not be said for the crankcase. These can be distorted and are rarely addressed since you need to remove all the cylinder base studs to skim the surface true. You also could have miss-matched case halves from different engines. Lots of gasket cement/sealer is the standard short-term fix. But if the cylinder is not sitting square on the joint face, particularly front to rear, the cylinder bore will not be perpendicular to the crankshaft axis and you may have problems with piston/bore wear and running hot/seizures. It would be similar results to having a bent connecting rod.

Head gaskets have always been a problem. I do not like the currently available cardboard versions (they settle and blow out) and the original copper clad asbestos are superior though very hard to locate. I switched mine over to solid aluminum sheet fifteen years ago, and that was the end of that problem.

If you are leaking oil from the rocker cover joint, then I wonder if you do not have excessive crankcase pressure. This could be the rings not bedding in, and/or the original breather in the timing chest cover being blocked.

-Doug

[eddie]

    Contrary to what Doug said earlier, the original cylinder base 'gaskets' were, in fact, brass shims - these were used in the belief that they would act as a barrier and prevent any corrosive action between the alloy crankcases and the iron barrels. The replacement gaskets supplied by the LDMCC are of the more conventional 'Klingerite' type material.
     As even a relatively small high spot on the crankcases could cause a considerable leak from these joints, I would suggest removing the barrel and piston, and then the six retaining studs - then the barrel can be offered up and the gap checked with a feeler gauge. The problem may be no more than 'pulled threads' leaving high spots around each stud. Careful removal of any high spots on the crankcase should cure the leak, but as Doug says, will not guarantee perfect squareness with the crankshaft.
    I am also in agreement with Doug on the subject of thicker gaskets - if there is any distortion of the joint faces, using a thicker gasket will only increase that distortion - maybe to the point of fracture. Cracked base flanges on Mark barrels are relatively common - sometimes, whilst not being obvious on the outside, the crack actually goes right through to the bore.
                                   Regards,
                                            Eddie.

[trevorp]

dare i mention the words crankcase compression lol maybe  a venting issue  blocked breather