Oil leak

[AdrianS]

Hi all,

Just an observation.
I am about to start stripping my A50 engine in the frame to find the source of some unexplained noises.
I previously changed my oil pipes to the later ones with the direct feed to the rocker gear. Since doing that, every time I park the bike on its side stand after a run, I get a substantial leak from the left head barrel joint. If the bike is on the centre stand this doesn't happen. I assume the new feed is putting a lot more oil into the rocker box and when parked up it is draining possibly down a head bolt and the gasket is not sealing well. Never had this with the old oil supply!

[DAVE BRADY]

Hi Adrian,

Rather than just rely on memory, I have just checked some photos of a cylinder head and would think that there isn't a place that would hold much oil.  The head bolts sit quite high up and there is quite bit of drainage from the rocker box.  It will be interesting to see what you find.

Dave.

[AdrianS]

Strange that no oil leaks with the bike on the centre stand but does on the side stand..
The amount that leaks out in say 1/2 hour after a run leaves a patch about 4 inches across on the tarmac.

[ChrisG]

The oil drain from the Exhaust valves in the rocker box goes down two small holes from just under the valve spring cups, via the head gasket and comes out at the Barrel base inboard of the cylinder extensions. My guess is your LH hole is blocked (easy done with gasket goo etc.) and the oil is finding its way between head/head gasket/barrel. Reason it shows up  when leaning is probably due to gravity when the barrel is hot and the oil, also hot, is heading downwards and dripping off the end of the fins. When upright, it's there but slower to move as its level, (no downhill run) and as it cools it's less likely to move anyway.

The head/barrel joints on A50/65 are notorious for leaking and the best way of sealing it is to use bathroom sealant (sparingly) on the joint top and bottom. This is a tip from SRM by the way. I've been doing it for years and never had such problems since.

Of course, make sure you keep it away from the aforementioned drain holes and I always make sure the holes in the barrel are clear by shoving a piece of thick steel wire down before putting the head on.

Let us know what you find when you strip it down

[AdrianS]

Cheers
Will do!

[DAVE BRADY]

Hi,

I think that some A65s had 'O' rings put in the gasket where these drain holes are although I have not seen any in gasket sets.
It may have been a suggestion rather than a standard fitment.  I think (I should know) I have just put some on my bikes as I had the heads off recently.

Dave.

[Bess]

Hi Adrian,
               It maybe worth checking the rear head bolt size, the head bolt washer sizes and if you have a solid head gasket. The head bolts were 5/16", changing to 3/8" in 1968 which cured the head gasket sealing issues and the washers changed to 0.750" x 0.380" x 0.092" which helped with spreading the load from the bolt/nut to the head.

If you are going to strip down, buying the parts from SRM Engineering would ensure good quality parts as there is a lot of sub standard being offered.

Best wishes...