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750 Breva puking oil

ErikK

Just got it firing!
Joined
Jan 24, 2013
Messages
13
Oil is dripping from the drain tubes, it made quite a puddle after a spirited ride. The drain tube from the bottom of the airbox turned out to be cracked so that's one thing. But... there is also evidence of new oil leaking out all over the engine.. around the cam sensor and several other places. It smells to me as if the crankcase is pressurized and can't vent properly.

1.. The Guzzi shop manual mentions a "non return valve" in the PCV system but where is it?
2.. As far as I can tell all the PCV related hoses go into the bottom of the airbox. How can I open this up or remove it to see what's inside?

I opened up the dipstick while the engine was running at idle. There are strong pressure pulsations pushing and pulling the dipstick plug, but it's not clear that the average is pushing more than pulling, Then I disconnected the vent hose from the right rocker cover and tested again, there was not a clear difference. So the new oil grime on the outside of the engine points to crankcase pressure, but this quick test at idle didn't show it.

What should I test next? How to find and fix this problem? All advice is welcome.
 
Look for a hose from the crankcase to a pipe, probably venting to the atmosphere or pointing to the ground. Along its route you should find a one-way valve. Pull it apart, remove its innards and replace.
 
The oil level is about 3/4 up in the zone on the stick. This is checked with the bike upright and the dipstick just resting on the threads, not screwed in. Is that the correct procedure for this bike?

There is a hose that goes from the back of the oil sump up to somewhere. It doesn't go down and out, it probably goes to the bottom of the airbox where there is some kind of oil separator or something. I will trace it and see if I can find anything. There is a separate hose from the bottom of the airbox going down, but it is plugged, not open.
 
There is an oil drain from the breather oil seperator back down to the sump. There is also an airbox drain which should be plugged. You should drain that periodically. Have you done so? If you have got too much oil in the airbox goodness knows where it will come out.
Try dropping the oil level to the halfway mark.
 
Sounds like too much oil.
Probably true. My manual says the dipstick should be screwed in to check the level. Also, as with all bikes, the level should be checked warm. If you're topping up oil to the max line when its cold you've put in too much oil.

My model has a PCV line from the sump to the air box. It's an odd percolator/fluid airlock sort of setup. I've only owned one Guzzi so I can't really speak to other models, but it sounds very similar to mine. If your crankcase top vent is blocked, it may cause intake vacuum to excessively suck oil up into the airbox.
 
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