Motorcycle Discussions > British Bikes
1969 Triumph T120 Fresh motor and oil coming out the crankcase breather.
stevestriumph:
Well it's on to a different bike. The previous issue regarding the 1969 T100 was resolved when I found a piece of sludge sitting in the bottom of the crankcase drain plug. It was large enough to be drawn up and block off the intake scavenge return tube, causing the crankcase to fill up and blow out the breather. That was a first for me!
Now I have a similar problem but with a fresh rebuilt motor on a 1969 Triumph T120 Bonneville. Motor was completely gone through by a friend, (very qualified), who has passed on. My job was to get it running and sell it for his wife. Problem is oil is coming out the crankcase breather. I assumed "wet sumping" but did not have excess oil in crankcase. I pulled the top end to check rings and all was good. I re-honed and installed a set of rings and installed a new oil pump. Compression is good, I have good oil pressure and good return to the tank. I have put almost 50 miles on the bike. It runs great but continues to push oil out the breather. I have re-checked the sump and it's not over filling. Oil tank breather is clear as well. I am at a loss for what to do. Any thoughts? Steve
Rex:
How much oil is being pushed out? A smear? Continual stream? Put some miles on it and see if the problem remains. 50 is nothing.
A new oil pump though? Bit of an expensive suck-it-and-see approach?
iansoady:
I'm not familiar with the model but does it perhaps have a timed breather?
mini-me:
Breather on end of camshaft has not been assembled properly, or oil pump is not returning to tank.
the latter problem is more easily resolved, the former is an engine strip.
check pump and return first.
Oggers:
50 miles is nothing to allow the new rings to seat properly. Drain the sump again, and as aforesaid, put some miles on it.
Another possiblity is the return vv in the oil pump is blocked, or the return line to the tank is kinked or blocked. Thus the pump delivers more than it can scavenge, leaving the residue in the sump and causing the breather issues seen.
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