Timing cover leak

[Oggers]

Chaps

Oil flowing out of the top edge of the mating suface twixt timing cover and crankcase. Oily right boot and gearlever ensued. Bike (59 Matchless G9) is newly overhauled - not by me - so currently cautiously riding around to establish confidence.

To remedy the above, cover removed, mating surfaces flattened as much as feasibly possible, screw holes deburred, flexoid gasket made, mating surfaces painted with Wellseal, Monograde 50 to be used intead of the previous 20/50. All now ready for test ride.

Qs

The leak was close to the oil pressure relief valve - spring and piston affair in the crankcase. Would there be any preponderance for a leak in this area? I am guessing that the void under the cover should not be pressurized.

Any thoughts as to root cause - apart from dodgy mating surfaces.

Many thanks



   

[iansoady]

Are you sure the return side of the oil pump (actually I seem to remember that the AMC twins had 2 pumps) is working? There should be no more than oil mist in that area. I don't know the engine in detail but oil pressure release valves usually open to allow excess pressure back into the timing cover so you may be on to something there.

Did you get this instead of the Triumph? Much nicer bike IMO.

[Oggers]

Ian

Pump return flow is fine back into the tank - so I assume no issues there. Pump is seperate gear arrangement for both supply and return. A swine for wet sumping....but that's another story.

PRV I believe just allows oil pressure to build up for onwards distribution? The piston and spring seem fine - so I assume unless it is relieving pressure, oil is going where required rather than into the timing case. Even if it did relieve, pressure within would be practically zero due to volumetric expansion, unless full of oil  !

It's an addition to the Triumph. Comparing and contrasting is quite interesting.   

[iansoady]

What the PRV normally does is to prevent excess oil pressure getting to the bearings etc, especially with cold thick oil. Usually what happens is that the valve is forced off its seat against spring pressure, and what comes out (which would be oil) generally gets sprayed around the timing gears etc. It's normal for the valve to lift under normal circumstances but obviously not all the time.... And clearly it shouldn't come out of the joint you mention. Maybe a breathing problem?

Have you had a delve in Christian's archive which has everything anybody ever wanted to know about AMCs? http://archives.jampot.dk/

The AMC forum is good as well although I think you need to join the club to get full access.

I thought you decided against the Triumph?

[Oggers]

I shall run it again and see. I am assuming the initial problem was the joint wasn't great. If it leaks again from the same place now, then yes, breather diaphragm or something - I have already cleaned out the foam filter thing.  Already a member of AJSMOC - very good club, and have had some good responses.

Triumph refers to existing 66 Bonnie.