Oil pipe union gasket?

[Phil C]

Good morning all,
I see that on my 1965 B40F the oil pipe union, where the two metal pipes (oil feed and return) meet the engine, there is a little 'O' ring in each pipe, but also there is a gasket where the two joined pipes meet the underside of the engine. I don't see a gasket on the parts diagram, so I'm guessing this was a ' belt and braces' decision by a previous owner. Would that be true, do you think? And is it a good idea?
Phil

[Spaceman]

The oil pipe union was of two types: the earlier one (40-0217) had the bolt hole and oil apertures in a line and used a gasket but the later union, as used by the B40 but not the C15, had a triangular arrangement of holes and used O-rings instead of a gasket.

Personally, I don't think this is a well designed way of joining the oil pipes to the engine and I prefer a gasket to O-rings although there is no problem in using both together provided teh gasket is accurately cut.

[cdsdorset]

Most of the o rings supplied for this job are useless. If you shop around you can find "quad rings"

[chaz]

one factor is the shape of the o rings, the square shaped ones are the correct type . cover more surface area.
Ive just had the forks out of the B40 as left one was leaking after powder coating and reassembling, got the file out and the face wasnt flat enough for the new washers. filed the face and applied paint to the surface , hopefully sealed now. This is the main thing regarding the sealing of o rings on the oil union.

the case face needs to be clean and flat likewise the bottom faces of the holes needs to be clean and flat, clear of old oil or gasket goo.
some "dealers" sell normal black o shaped section o rings, these dont give the same sealing area. Also , metric o rings may be thinner 
2mm = 0.078", 2.5mm = .097"  , 3mm =0.0117".    3/32 = .096" therefore if 2mm used they wont seal then , if you use a thicker one, the whole casting with pipes  and hoses weight can move as sits on rubber which can give and cause a leak.
best to check depth of holes, may have had face filed flat before , then select best fit o rings.

[Phil C]

Sounds like problems with 'O' rings might be why a gasket has been used as well. But then I'd have thought the thickness of a gasket would mean the 'O' rings would be doing nothing.

Phil