Posted by L.A.B. on 7/28/2009, 8:49 pm, in reply to "T140V oil draining into sumo?"
82.22.53.127
Yes, your engine oil is almost certainly draining down to the sump while the bike is left standing. Commonly referred to as "wet sumping" by many people these days (although the term "wet sumping" actually means the failure of the scavenge system to clear the sump of oil during normal running).
As soon as you start up, the scavenge system will start returning the excess oil in the sump back to the frame reservoir, so only check and top up the oil level after the engine has been running for a few minutes.
Oil draining to the sump is a fairly common problem found on many older British bike engines as they may not be ridden daily as they would have been in the past, so the oil has much more time to drain through the oil pump.
However, Triumph twins do not generally tend to suffer from this problem as badly as some other British bikes do, (and I can leave my T140 for weeks and the oil level doesn't drop) so maybe the ball valve on the feed side of the pump isn't seating properly, so oil is getting through?
Or maybe the pump is worn, in which case the oil can escape through the increased clearance between the pump feed plunger and its bore, as there is no inlet 'valve' as such, on these pumps?
Or the oil could be leaking from the pump to crankcase joint if the pump gasket has failed for instance?
<<If i top it up it blows out of the breather pipe under the tank.>>
That pipe should tee into the engine's primary breather system pipework (and 'D' pipe), it shouldn't be open, allowing oil to blow out?
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